serving: recording, broadcast and sound contracting fields ......cover why a leading manufac-turer's...

March/April 1989

THE SOUND ENGINEERING MAGAZINE $2.95

serving: recording, broadcast and sound contracting fields

Guides: Amplifiers

The impressivenew AT4031 Studio Cardioid

Capacitor Microphone.

Our new AT4031 makes a greatfirst impression. And it buildsfrom there. The sound is effort-less and natural over the entirespectrum of voices and musicalinstruments. It's the result ofwide, flat frequency response,low distortion, and excellentdynamic range.

Very fast transientresponse

The outstanding performanceis the product of uncommon pre-cision inside the fixed -chargeelement. The diaphragm is only0.00016" thick (just 4 microns),including the ultra -thin vacuum -

deposited gold conductive layer.Very fast transient response andwide bandwidth are assured. Withits high sensitivity ( 44 dBm)

and low distortion, the AT4031meets the stringent dynamicrange demands of todays stor-age and playback media.

Uniform, predictableperformance

You'll find the AT4031 veryeasy to use. The uniform, predict-able cardioid pattern translatesinto off -axis attenuation, not col-oration. An integral second -orderhigh-pass filter lets you roll off thebass at 12 dB per octave, whenwind noise or room rumble mustbe controlled. An effective foamwindscreen is also standard.

No -compromiseperformance

The AT4031 is intended forthose professionals who will

accept no compromise in per-formance, yet need a tough, reli-able microphone. But, listen foryourself. Based on extensive fieldtests in studios and on stagesaround the country, we thinkyou'll agree that what you hear isprecisely what you need...thenew AT4031 Studio CardioidCapacitor microphone.

audiotechnica.Circle 10 on Reader Service Card

1221 Commerce Drive. Stow, OH 44224(216) 686-2600

see page :).2

see page 60

About the Cover On our cover, The San Diego

Sports Arena. The story begins onpage 6.

Photo credit: Greg Schenewerk.

MARCH/APRIL 1989 VOLUME 23 NO.2

ACOUSTICAL DESIGN FOR LARGE FACILITIESMichael Klasco

ON TOUR WITH THE DIXIE DREGSCorey Davidson

CONCERT LOUDSPEAKER PROCESSORSAndrew T Martin

SYSTEM INTELLIGIBILITY CRITERIAJohn Eargle

PIANOS I HAVE KNOWNRobyn Gately

SOUND REINFORCEMENT IN CENTRAL AMERICAAND THE CARIBBEAN, PART IEd Learned

LAB REPORT: SOUNDCRAFTSMEN 300X4POWER AMPLen Feldman

AES SEMINAR ON LIVE THEATER SOUND DESIGNBruce Bartlett

6

18

25

28

35

42

48

56

faex4441 c4+4-%,A-JAGGER DOWN UNDERIan "Mack" McKenzie

60

014 tit,Akiva, e44ciz44teil

AD VENTURESBrian Battles

BROADCAST AUDIORandy Hoffner

32

62

A MINIMALISTIC PHILOSOPHYRick Shriver

38

MIKE MANDEL: THE SONGWRITER'S DREAMMAKER 52John Barilla

LETTERSCALENDARBUYER'S GUIDE: AMPLIFIERSNEW PRODUCTSCLASSIFIEDPEOPLE, PLACES, HAPPENINGS

24

67758081

Laitm,

Dear Friends,I find db Magazine to be very helpful

and informative.I especially appreciate the articles

pertaining to sound reinforcement andsmall studios.

I am looking forward to my new sub-scription.

Also I hope that you will soon includearticles on speaker placement and sys-tem design for different halls and audi-toriums.

Sincerely,Dana Allasin PowersMessiah SoundLakeland, FL

Your wish is our command! See the ar-ticles in this very issue. Ed.

Dear Editor,

It has come to our attention thatseveral comments in a recent article(see db, September/October 1988)concerning the construction of ournew production facility have offendedDr. Peter D'Antonio, the founder ofRPG Diffusors, and Russell Berger ofthe Joiner -Rose Group. In the articlewe related our experience with build-ing our own studio, including the con-struction of custom-made diffusors,but did not credit Dr. D'Antonio for hispioneering work in designing and con-structing diffusors of this type. We didnot mean to make any negative infer-ence whatsoever with regard to Dr.D'Antonio's work, for which we have agreat deal of respect, nor did we mean

our comments to infer that our diffu-sors were in any way superior to RPGdiffusors. 'lb be perfectly honest, we re-ally did not know if our diffusors wouldwork at all, hence the statement in thearticle that they "exceeded expecta-tions." In fact, our diffusors probablydo not work as well as Dr. D'Antonio'sRPGs, and we make no claims what-soever regarding their performance inrespect to his. We wish to apologize toDr. D'Antonio for the unintendedslight in not crediting his design work,and deeply regret any offense caused bythe article.

We did not credit Russell Berger ofJoiner -Rose Group because we did notthink he would want to be credited,since we did not implement all of hisideas due to cost and other considera-tions. Russell Berger was compensatedfor his advice, so his ideas were not ex-propriated. However, we would be thefirst to admit that Russell extended hishelp as a friend far beyond that whichwas requested. He noticed several mis-takes and errors in calculation in ouroriginal design, and called them to ourattention. In the last few paragraphs ofthe article, I was quoted as saying,"There were many times during theconstruction when I wished I had justcalled Russ Berger or someone, andhad them do it." We have the highestregard for Russ Berger's work, andappreciate his help in designing FutureAudio.

Yours truly,

Tbny Rodriguez

Owner, Future Audio, Dallas

Editor/PublisherLarry Zide

Associate PublisherElaine Zide

Associate EditorCarol A. Lamb

Technical EditorCorey Davidson

Contributing EditorsJohn Barilla

Bruce BartlettBrian BattlesDrew DanielsLen Feldman

Robyn GatelyRandy Hoffner

Graphics & LayoutKaren Cohn

db, The Sound Engineering Magazine(ISSN 0011-7145)Is published Bi-monthly by Sagamore Publishing Com-pany Inc. Entire contents copyright 1989 by SagamorePublishing Company Inc., 203 Commack Road, Suite1010, Commack, NY 11725. Telephone: (516)588-8530.db Magazine Is published for individuals and firms inprofessional audio recording, broadcast audio-visual,sound reinforcement -contracting, consultants, videorecording, film sound, etc. Application for subscriptionshould be made on the subscription form in the rear ofeach issue. Subscriptions are $15.00 per year($28.00per year outside U.S. Possessions, $18.00 per year inCanada)and payable In U.S funds. Single copies are$2.95 each. Editorial, Publishing, and Sales offices areat 203 Commack Road, Suite 1010, Commack NY11725. Second Class postage paid at Commack, NY11725 and an additional mailing office. Postmaster:Form 3579 should be sent to db Magazine, 203 Com-mack Road, Suite 1010, Commack, NY 11725.Trademarked names are editorially used throughout

this issue. Rather than place a trademark symbol nextto each occurance, we state that these names are usedonly In an editorial fashion and to the benefit of thetrademark owner, and that there is no intention of trade-mark Infringement.

Sound Thoughts on Live Performance"Creating the subjective

experience of live performancesound belongs to the artists andsound designers. Our creativitycomes in building speakers andsystems that give the truestpossible account of what theperformers produce."

Meyer Sound has devoted itself to designing,manufacturing, and refining componentsthat deliver superb sonic reproduction andexpand the artistic possibilities of professionalsound reinforcement.

Meyer strives for professional sound qualitythat is predictable and neutral over an extendedlifetime and across an extended range. Evenafter extended use, Meyer Sound performance isnever compromised.

As a consequence, Meyer Sound productshave earned a reputation for the highest relia-bility in the industry. All are guaranteed to meetor exceed specified performance levels whenproperly installed.

"The general public's sophisti-cation keeps growing. Soon, if wehave our way, the audience willdemand the same accuracy in liveperformance that they get fromhome recordings."

Instead of second-guessing the tastes of themarket, Meyer produces sound systems that mosttruly represent the character of the signal theyreceive, leaving artistic control where itbelongs-with the artists and sound designers.

Meyer takes a conservative view of exoticloudspeaker materials, preferring to use provenmaterials in new, more elegant ways.

Every part of every component undergoesrigorous, comprehensive testing. Meyer Soundcontrols all aspects of the system design-if notby manufacturing, then by modification andrefinement to Meyer's stringent standards.

John Meyer, Founder andPresident, Meyer SoundLaboratories

"As expectations rise, our perfor-mance standards have to rise evenhigher. And the only way to increaseperformance is with increasinglysophisticated measurement.

"Which is how we found ourselvesalso in the measurement business."

Meyer originally intended to be solely a manu-facturer of high -quality, rugged and reliableloudspeakers, expecting others to pioneer andperfect testing equipment. But the need to accu-rately measure the performance of Meyer com-ponents individually and in arrays outgrew thequality and resolution limitations of availabletesting equipment.

To make sound work in spaces, Meyer SoundLaboratories developed by necessity its own test-ing technology and methods.

John Meyer, his engineers and his designershave authored several definitive works, andresearch remains an integral, driving force behindall production.

SIM' EqualizationSIM- equalization is the logical result of

Meyer's commitment to uncompromised soundquality through sophisticated measurement. Thenon -intrusive SIM technology uses real -worldprogram material (either voice or music) as thetest signal. Working interactively with the sounddesigner, a Meyer SIM engineer helps create supe-rior clarity for every member of the audience.

Ask your distributor for more information onSIM equalization, or call Meyer Sound Laborato-ries direct.

Circle 13 on Reader Service Card

MeyerSound

John Meyer's involvement inloudspeaker design began in1967 when, as a technicianfor a Berkeley. California Hi-fisupplier, he set out to dis-cover why a leading manufac-turer's drivers kept tearingthemselves to pieces. furtherinvestigations convinced himthat the market sorely neededa class of rugged professionalspeakers that would mainta,ntheir characteristics over time.

Research in Switzerland in the

early seventies secured hisknowledge base. In 1972.Meyer developed the JM3 anhorn loaded tri-amp systemwith rigging, which was thestandard for Broadway showsuntil the introduction of theUPA in 1980. From 1973 to

1979, Meyer sought out the

best available parts anddesigned the first UltraSeries reinforcement speak-ers. In the decade since,John Meyer has establishedMeyer Sound Laboratories atthe forefront of professionalreinforcement technology.

Soundengineeringfor the artand scienceof sound.

Meyer Sound Laboratories, Inc.

2832 San Pablo Avenue

Berkeley, CA 94702

(415) 486-1166

FAX (415) 486-8356

Cd14.41/41,

EDS '89 (Electronic DistributionShow and Conference), the nationalforum and marketplace for electronicdistribution, will be held at the LasVegas Hilton Hotel, in Las Vegas,Nevada. Conferences and seminarsstart on Monday, May 8, and exhibitsopen on Thesday, May 9 throughThursday, May 11. The annual event issponsored by the Electronic IndustriesAssociation/Distributor Products Di-vision (EDVDPD), the National Elec-tronic Distributors Association(NEDA), and the Electronics Repre-sentatives Association (ERA).

Information about EDS '89 is availa-ble from the Electronic Industry ShowCorporation, 222 South RiversidePlaza, Suite 2710, Chicago. IL 60606,(312) 648-1140.

C)corn

Pro Audio Asia '89, the inter-national trade exhibition for pro-fessionals in the broadcast, recording,public address, installation, con-tracting, and duplicating industries,will take place from July 6-8 1989 at theHong Kong Exhibition Centre in HongKong.

A four -week program, comprisedof eight accredited graduate levelcourses in acoustics and signal pro-cessing, will be offered in June 1989 byPenn State's Graduate Program inAcoustics in cooperation with the Uni-versity's Applied Research Laboratory(ARL) and the Research Center forAcoustics and Vibration Engineering(RCAVE). Courses offered includeFundamentals ofAcoustics,Underwater

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For further information contact: Dr.Alan D. Stuart, Summer ProgramCoordinator, the Penn State GraduateProgram in Acoustics, PO Box 30,State College, PA, 16804, (814) 863-4128, or Mrs. Barbara Crocken at (814)865-6364.

The APRS (The Association ofProfessional Recording Studios) hasnow opened its bookings for standspace at the 22nd annual internationalexhibition for the recording industry,APRS 89. It will be held at Olympia ex-hibition centre, London, on Wed-nesday, June 7th to Friday, June 9th.

More details are available from:APRS, 163A High St, Rickmansworth,Herts. WD3 lAY, England. Telephone(STD 0923) 772907, (International)+44 923 772907.

The New England Conservatory isoffering summer music workshops.The course titles are Musicians andTechnology, Electronic Music Work-shop, and Controlling Your MIDI. Theworkshops will take place in June,1989. For more information, contactMary Street, Director of SummerSchool, (617) 262-1120, ext. 283.

Architectural Acoustics Standards,a two-day workshop sponsored byASTM (American Society for Testingand Materials) Standards Technology'Damning, will be held May 1-2, 1989 inGeneva, Illinois. The workshop willfocus on the basic principles and prac-tical applications of architecturalacoustics, and will include laboratorydemonstrations, a tour of RiverbankAcoustical Laboratories, and athorough review of 15 related ASTMstandards. For more information, con-tact Kathy Dickerson, ASTM Stand-ards Technology 'Raining, 1916 RaceSt., Philadelphia, PA 19103, (215) 299-5480.


HME Intercom Systems:

First for Performance,Built to Last.HME intercoms are fast becoming thefavorite of concert halls, theatres andchurches.

It's well known that superior audioquality reduces fatigue and makes forless mistakes. Which is why HME'sbrcadcast-quality audio means a lot toproducers who care. We even haveAGC on every mic line so everyone fromshouters to whisperers are understood.

HME intercoms are truly built with theuser in mind, from form -fitting belt-pacsto compact wireless transmitters, andfrom hands-off power s:ations to modelswith IFB, stage annource, telephoneinterface, and up to 6 x 12 matrixswitching.

They're unbeatable for reliability. Cur-rent foldback in the power supplieseliminates damage to components fromshort circuits, and acts as an exclusivebuilt-in fault locator to help you h. -idshorted cable quickly. HME's years ofwireless microphone experience hashelped develop the most rugged elec-tronics packaging this side of space.

HME designs and manufactures 100%of our cabled and wireless intercomequipment, so custom designs andinterfaces can be made much fasterwith the same high reliability as ourstandard products.

Call your HME dealer/distributor nowfor all the details.

h m eHM ELECT1ONICS, INC.6675 Mesa Ridge RoadSan Diego, CA 92121, USAPhone: (619) 535-6060Telex: 350-771FAX: 619-452-7207

HME Products are distributed internationally:In Canada -GERRAUDIO Distribution Inc. PH: (416) 868-0528 FAX: 416-868-6419In Central and South America- Servicios Electronicos al Espectaculo PH: (905) 544-1345 FAX: 549-6509All other countries-Global Representatives. Inc. PH: (201) 492-8140 FAX: 201-492-2566


MICHAEL KLASCO

Acoustical Design forLarge Facilities

sound system contractorstend to view room acous-tics as the dark side ofaudio. Certainly, all willconcede room acoustics

and sound system performance areintertwined, nevertheless, proposalsfor acoustical analysis and remedialmeasures are typically avoided bysound contractors. The sound systemand the room are like a car on a road.The performance limits are interac-tive and optimum selection of one isdependent on the other. A facilitywith highly reflective walls restrictsdesigning for uniformity of directsound coverage as any spill -over willincrease the perceived reverberationand may result in flutter echo. Con-versely, the same space after acousticmodifications would allow a differentselection of horns (a lower Q cluster)and more even coverage, as much ofthe spill -over would be absorbed bythe acoustic treatment on the walls.

Just as equalizers, time delays,limiter/compressors are used to ensurethat the sound system performs its in-tended functions, modification ofroom acoustics also are often a neces-sary ingredient in achieving intelligi-bility, non -fatiguing and aestheticallypleasing sound reinforcement. Some-times dealing with the acoustical prob-lems is the only way the sound systemwill successfully perform its intendedpurpose. Remember, even more than agood sound system, your client wantsgood sound!

While most sound contractors arenot equipped to solve serious acousti-cal problems, without the assistance ofan acoustical consultant, they can usu-ally sense when a space has an acousti-cal problem. Echos and longreverberation times are not subtle de-fects. At times sound contractors arecalled in to fix sound system problemswhen room acoustics are the real cul-

up prit. The sound contractor can act as

the early warning system when pooracoustics are encountered.

I am often contacted by sound con-tractors attempting to make sound sys-tems work in unworkable spaces. Someof the sound systems have undergonecomponent changes, re -aiming, etc.,but without significant improvement.When the mid -band reverberationtime (RT60) is greater than four sec-onds, the only electro-acoustical solu-tions are headphones or pew -backspeakers!

During the past few years I haveworked with some sound contractors inimplementing acoustical solutions.Conventional surface treatments areusually installed by general contractors(or "acoustical contractors," but manyof these firms are no more thandropped ceiling installers!)

In the acoustical renovations I havedesigned acoustic devices with wide -

band, high -absorption coefficients areinstalled by a sound contractor that iscompetent with rigging techniques.Often the sound contractor may al-ready be handling the equipmentmaintenance and is now being asked bythe facilities management how to im-prove the sound quality, but other rea-sons point to the sound contractorinstalling the acoustical devices. As thesound system design is closely linked tothe acoustical treatment, the soundcontractor should be involved withthese aspects of the job. If the reverbtime is close to four seconds or more,instead ofjust attempting to use high Qarrays, located close to the audience(which still may be needed after treat-ment), the space should be studied byan acoustician and acoustically treat-ing the room should be considered.After acoustical treatment, the sig-nal/noise (intelligibility), the uniform-ity of coverage, and sound quality willbe superior to results limited only tohigh Q clusters.

A HANDFUL OF ARENAS

Many sound contractors are aware ofacoustical design for recording studiosand concert halls, but avoid this workbecause of its critical nature. Record-ing studio acoustics arc hypercritical.Competition here is keen and the cus-tomers have "golden ears." Achievinghigh definition sound at intense soundlevels in tiny control rooms is problem-atic. Acousticians who conceive thesedesigns, or attempt remedial measuresare artists walking a thin tightrope.

Some criteria and guidelines havebeen established using LEDE tech-niques which are taught through Syn-Aud-Con and results are becomingmore predictable. LEDE tries to stand-ardize (and neutralize) the controlroom acoustics through control of ini-tial time delay, acoustical absorption ofcertain directional cues of the room,and manipulation of the reflectedsound field's density, temporal ele-ments and intensity.

At first glance, concert hall acousticsmay seem less critical, but actually alsoare very complex problems. Many su-perior halls exist, and the form factorcan be emulated. The rub is that whileit is possible to design an excellent hallfor an audience of up to one or twothousand, economies of scale seducethe sponsors of new facilities todemand larger and larger halls. Goodsounding halls for three thousand ormore are very hard to create, and theacoustic compromises of having un-amplified music be audible throughthese facilities are serious. Acousticalinnovations used on these jobs have amixed record and every year one hearsof how these halls struggle on with re-medial measures. The use of reflective"clouds" have had marginal successand have been shown to have a delete-rious effect on low -frequency re-sponse.

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CO

Figure 1. Wedge contoured 3 -inch acoustical foam on the ceiling.

Manfred Schroeder, who headed BellLabs (and gave us the concepts for elec-tronic reverberators, electronic timedelays, pitch shifters, etc.) conceived ofa predictable wide -band diffuser ofcontrolled characteristics. Dr. PeterD'Antonio developed and commer-cialized a family of diffusers based onSchroeder's work. Aside from record-ing studios, these devices have beenused with excellent results in facilitieswhere architectural acoustics, ratherthan a sound system, is the preferredmethod of reinforcing speech andmusic. These wide -band diffusers are

very powerful in channeling otherwisewasted or deleterious sound energyinto effective use.

Yoichi Ando's research (ConcertHall Acoustics, Springer Verlang) hassuggested that non -lateral (ceiling) re-flections detract from the aestheticsound quality. In concert halls, dif-fusers can effectively re -direct ceilingreflections away from the audience andtoward the side walls where this energywill both improve the reverberationdensity and direction of arrival at theaudiences' ears from a spatially morepleasing direction. One of the parame-

Figure 2 Wide -band diapitragmic absorbers in the gym.

411

Mb

1 111111 V

ters Ando uses as a figure of merit is theIACC (Inter Aural Correlation), whichrelates to the correlation of the reflec-tions and their arrival times at each ear.We can see the benefit of re -directingthe reflected sound energy from theceiling toward the walls (instead of ab-sorbing it) helps preserve the limitedenergy acoustically generated by an u n -amplified performance.

Ando uses impulse testing andpseudo -random signals as the excitingsignal, although it would be possible totransfer some of his work to TEF tech-niques. Ando believes that by analysisof energy/time/frequency information,and their correlation (using a dummyhead), the subjective qualities of anacoustic space can be determined.Ando's work can be used by acoustici-ans as a guide for modeling halls, just asstudio designers are using LEDE con-trol room design. While Ando's work isa powerful tool in analyzingenergy/time curves, we must rememberthat a symphony orchestra rarelygenerates more than an acoustic watt,while a large arena is an entirely differ-ent animal.

In a sports arena the house sound sys-tem typically has 10,000 electrical watts(100+ acoustical watts) and a rentaltouring sound system may have 50,000to 200,000 electrical watts. (It is notgood aural hygiene to even think abouthow many acoustical watts this is!)

Instead of 2000 seats, we may have20,000 seats. Most arenas were origi-nally designed for sports events such asbasketball, ice hockey, or soccer. Ar-chitects for these facilities pay little at-tention to acoustics with the focus onease of maintenance and durability. In-teriors tend to be hard, as acousticallyreflective surfaces such as concrete, ce-ment, plaster, steel masonry and hard-wood are the dominant constructionmaterials. Seating is often moldedplastic. Even the newest facilities thatuse "acoustic treatment" usually haveimproved characteristics only above1000 Hz, with the low frequencies stillout of control. Flutter echoes, poor in-telligibility, and high ambient noise arethe norm. When Ando's criteria are ap-plied to studying the sound field inthese spaces, the results indicate whythe sound quality is so poor. Crowdsounds are accentuated by noisy, cav-ernous acoustics. Announcements andnarrations of events tend to be fatigu-ing and musical performances are aes-thetically marred and generallyunacceptable.

TASCAM WE'VE FIT EVERYTHINGWE KNOW ABOUT

16 -TRACK RECORDERSINTO A HALF -INCH.Just how much caocioility did we fit into

cur new half -inch, 16-trac< recorder? At leastthirty years' worth. That's how long we'vebeen making innovative multitrack recorders.

Not surpr6ingly, the MSR-16 is like no16 -track you've ever seen At last a half -inchmachine gives you the k nd of controlintelligence and automate features foundon professional recorders at about twicethe price.

The MSR-15 is as advanced as you care tomake it: you can synch video, or MIDI -casediistruments through a standard synchronizercr Tascam's MI.Di2ER: and a serial interfacea lows computer control. The pnopr etaryheads with dbx Type noise reductiondeliver flawles5 sound, and exclusive circuitryassures gapless, noiseless punch in/out.

So cont compromise your music bycompromising on your recorder. See yourTascam dealer today. With the MSR-16, therewe no compromises.

TASCAMC "989 TEAC America, Inc., 7-33 Telegraph Road,

Morviebello, CA 906.40 /13/726-0303

dbx is a registered tredenark of dbx, Inc.


Figure 3. Acoustical foam and diaphragmic absorbers.

While most arenas are designed forsports events, much of these facilities'revenue is now derived from rock con-certs. These venues must meet thedemands of today's more discerningaudiences. The great strides made bythe music and audio industries over thelast few years had profoundly alteredthe expectations of the typical concertgoer. As a concert ticket costs morethan a digital disc, the live concertsound has at least the realism, dynam-ics and clarity of the disc.

Most competent sound contractorsoften try to make the best out of a spacewith poor acoustics. lb minimize theroom's deleterious effect, highlydirectional speakers are located asclose as possible to the audience. While

this approach will improve the ratio ofdirect to reflected sound reaching thelisteners, it cannot help with control-ling crowd noise. Poor signal-to-noiseratios will degrade intelligibility andrequire higher system gain and reducefeedback margins. When the facility isused for concert events, the house sys-tem is normally bypassed and the typi-cal rental sound system will result inthe usual acoustic chaos. Some soundcontractors and touring sound compa-nies have had enough bad experienceswith poor acoustics; they avoid thesejobs altogether. The comprehensivesolution is to control the acousticspace, which will allow more accept-able performance from the wide range

Figure 4. The Digisonir dr-47 Digital Sound Controller

0

of sound system configurations thatwill be used.

WIDE -RANGE ABSORPTION

Unlike concert halls, arenas need allthe wide -band absorption they can get.Rock concert touring sound systemscan radiate hundreds of acousticwatts.Non -lateral ceiling reflections shouldbe absorbed rather than diffused. Thisis not just to improve aesthetic quality(as in concert halls), but is required toachieve an acceptable signal-to-noiseratio from the sound system over thecrowd noise. A sports arena or gym-nasium that has been acoustically de-signed to an optimum specificationmay have a 10 dB lower reverberantsound field than the typical facility. Thecommonly used Puertz assumptionsfor intelligibility criteria use a 25 dBsignal-to-noise ratio. Often an un-treated facility will have an ambientcrowd noise of 80 to 90 dBC, with peaklevels of 100+ dBC. This would requirethe sound system to operate at 105-115dB with peaks of 130 dB. Although an-nouncers' avoid talking over peakcrowd levels, sometimes communica-tion under these conditions are critical("get off the field!").

As a practical matter, sound systemscannot operate at such excessive levelsas it would be offensive (at least for iceshows, circuses, sports events and thelike). Rock concerts do operate atthese levels and here the problem isthat the room is not "fast" enough. Thedecay time of the room must be quickenough that the previous sound(chord, sung phoneme) must have de-cayed in level sufficiently th4t the fol-lowing note can be perceived.' A

This is discussed in some detail byFritz Winckel in his book, Musical,Sound, Sensation (Dover, 1967). Poly-phonic music of the 1500s reflected thecavernous acoustics of the churches ofthe time, chamber music was obviouslynamed after the intended acousticalenvironment, and symphonic music in-tended to be performed in the concerthalls of the 1700s. Events move quickerthese days and arena architects havenot gotten the message yet. When thereverberation of the music and thecrowd noise is not being absorbed fastenough by the room, then the music be-comes a raucous din. Many theaters ofgood acoustical design (built in the1930s to 1940s) are now venues forpopular music. Although fan -shapedwalls, stepped ceilings, and otheracoustical techniques were integrated

Rands' Kling waited until he was sure. Waited until the exact equipmentwas des gned and manufactured-the board to his parameters. He has

finally assembled all the p eces for the ideal digital mastering sitJationNow he is absolutely sure. After mastering 200 gold and platinum

-As a member of the design team thatcreated the Neve DTC, it is fitting thatRandy Kling be among the first digital

masterng engineers to experience digitalaodio in a way only possible with the

NEVE DIGITAL TRANSFER CONSOLEThe, union of our creativities is what

makes masterpieces possible. -

Tony La.lgley.VP of Sales.

Neve

'Since the analog days ofthe .50s, Randy has

depended on Tannoy refer-ence studio monitors for

the truth, the whole truth.and nothing but the truth.

For 'he 80's and thedemanding age of digital,

now more than ever.Tannoy

Bill CauseMarketing Manager

Tannoy North America, Inc

'It is befitting that Ampex, the first magnetic tape manufac-turer to develop and market a digital audio tape, should be

the tape of choice for the first all digital mastering studio. Weat Ampex congratulate Randy Kling and are proud to be

part of his state-of-the-art digital mastering system

Warren K SimmonsSenior Product ManagerProfessional Audio TapeMagnetic Tape Division

Ampex Corp

records on the analog counterparts of -tis new digital pieces, hedeserves to feel sure. And nowhere in the world can the same combi-nation be found. Now he invites the music rdustry to finish theirmasterpieces on his master pieces.

"Ran. ly at Disc Mastering Inc receivedthe firs' Studer digital recorder deliveredin the U.S The D820X DASH format (Dig-ital Audio Stationary Head) joins our longline cf analog multitrack recorders. andshares with Mem a 40 -year history ofStuderpertormance and innovation "

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I"Sony Professional Audio isproud to be associated withRandy-by supplying digitalaudio equipment to createeven better masterpieces,and to proceed with him intothe future of this new andexciting technology "

Graeme GoodallSony Professional Audio Divi.son. Music City, U S A

We sal.Jte Ranov King for being amongstthe first major mastering studios to make sucha complete commitment to Monster -Cablewire technology with the re -wiring of DiscMastering Randy's commitment to re -wiringis of sucn a magnitude that he has taken thetime to wire through walls. fabricate his owncustom ifonstei-Cable interconnects. and

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Noel Lee, Head IvlonerMonster -Cable Produ.:ts Inc

into the design by the original archi-tect, the high -power sound systemsused today were never envisioned. Justthe energy generated from the stagemonitor system is beyond the effectiveabsorption of the room (let alone thestage area). Slap -back, unintelligibleverses, rumbling, boomy bass and hard,noisy and fatiguing mid -range andhighs are the result.

In the case of large facilities that usehigh -power sound systems, far moreenergy is typically generated than thespace can gracefully absorb. For thistype of space, wide -band absorptionrather than diffusion is required.

Wide -band absorbers have beendeveloped for control of reverberationand crowd noise in large facilities thatuse high -power sound systems. Typi-cally installed by sound contractors,they enhance the acoustics of arenas,night clubs, discotheques and gymnasi-ums.

Existing conventional acoustical sur-face treatments originally conceivedfor open plan offices and the like can besupplemented by these wide -bandacoustic absorbers. Conventional sur-face treatments are helpful in increas-ing the average mid -band absorptioncoefficient cost-effectively.

THE WIDE -BAND DEVICES

The Cylinder Absorber

An acoustical device specifically en-gineered for improving the sonic char-acteristics of large spaces. A hybriddesign combining 3.5 -inch thick wedgecontoured acoustic foam on its cir-cumference for absorption above 400Hz and Helmholtz resonator tuningfor low -frequency absorption. The Cyl-inder -Absorber achieves 20 Sabines ofwide -band absorption at lower cost perSabine than devices intended for re-cording studios. Other special con-siderations for large public spaceapplications are the fail-safe two pointAeroquip rigging hardware and fire -safe Class I/ASTM-E84 Melamineresin wedge contoured foam. Strong,but lightweight construction results ina 45 -pound device that will not be a sig-nificant structural loading factor.

Most wide -band absorbers use pas-sive low -frequency absorption tech-niques, essentially relying on thefriction or shearing action of dampen-ing materials to convert sound energyinto heat. This approach is adequateand appropriate when limitedamounts of absorption are required,but not when the output of a 100,000

watt sound system is thundering out ofcontrol in a theater, disco or arena!

An alternative approach for low -frequency absorption is the Helmholtzresonator. The Helmholtz resonatorhas a natural frequency of resonance,and sound is absorbed at this frequencyand at adjacent frequencies. A few in-dustrial noise absorbers have beenmarketed that use this technique forlow -frequency noise cancellation, butdo not have a wide enough bandwidth(to work with the acoustical foam forwide -band absorption) and have poortransient response. High -efficiency,low -frequency absorption is achievedin the Cylinder -Absorber by slots cutinto the six-foot high, two -foot diame-ter tube. The slots create the Helm-holtz resonator effect at the surface ofthe tube. Glass fiber on the inside andacoustic foam on the exterior providecontrolled resistive a periodic dampen-ing of the resonator Q, so almost an oc-tave of absorption is achieved. Thecenter frequency of the slots is stag-gered between 30 Hz to 300 Hz Energynot absorbed by the slots is diffused andenergy not absorbed by the wedge -con-toured foam is diffused by the tube, orabsorbed by the fiberglass within thetube.

Progressively above a few hundredhertz, the absorption is provided by thewedge -contoured foam. 'lb satisfy therigorous Class I, ASTM-E84 fire code,specifications typically required inlarge public spaces, Illbruck Illsonicmelamine open -cell foam is used (thesame material used in Sonia( 1). Flamespread of the foam is rated at 5, smokespread at 65. The foam is cut to a 3.5 -inch depth wedge contour which re-sults in an absorption coefficient betterthan 0.9 from 400 Hz to beyond 8000Hz

The Cylinder -Absorber is available inthe natural white foam exterior or incustom -painted colors. For applica-tions where the devices will be acces-sible to contact, a protectiveacoustically transparent shell of per-forated aluminum is available. Guifordfabric exteriors are optionally availablefor the protective shell version.

Future Developments

Menlo Scientific has been exploringwith Digisonix, a division of Nelson In-dustries, Inc., future potential uses oftheir digital sound cancellation con-troller technology in the areas of crowdnoise, flutter echos, and reverberantfields. By using this active noise control

concept, which is extremely effective atreducing low -frequency noise in ducts,it is envisioned to develop techniquesto improve the low -frequency per-formances in the areas of speech intel-ligibility. Active cancellationcontrollers are available for researchpurposes. As this work continues, pro-gress reports will be published.

While neither Helmholtz resonatorsnor diaphragmic absorbers are news,both these devices are the first com-mercially available, "industrial size"wide -band devices built specifically tobe cost-effective for large facilities thatuse high -power sound systems. Thenext device, the digital signal processornoise canceller, is brand new.

The unique aspects of acoustical de-sign for large facilities with h igh-in ten-sity sound systems have been discussed.Solutions have been successfully im-plemented in a number of facilitiesusing wide -band acoustic devices inconjunction with surface treatments.Future developments using electroniccancellation of crowd noise and/or far -field reverberation has been intro-duced.

ADDITIONAL READING

Donald Davis, "Design Room orSound System?" Project Notes/En-gineering Briefs, April 1973.

Don Davis and Chips Davis, "TheLEDE Concept for the Control ofAcoustic and Psychoacoustic Parame-ters in Recording Control Rooms,"JAES September 1980.

Yoichi Ando, "Concert Hall Acous-tics," Springer-Verlag, New York,1985.

Leo Beranek, "Concert -Hall Acous-tics: Meeting Place of Science andArt," Physics lbday, December 1986.

Fritz Wrinckel, "Music, Sound, andSensation," Dover 1967.

Michael Klasco and Rudy Paolini,"San Diego Sports Arena," db Ma-gazine, November/December 1987.

David Scheirman, "ReinforcedAudio-Better Sound for Arenas,"Sound & Video Contractor, January15,1988.

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ADDENDUM

Specific problems of ceiling, wall,and seating constructions can be_der tified and remedied.

Ceilings

Non -lateral reflections are notconstructive as most arena ceilingsare over 80 feet. These(not-so- early)reflections reduce the clarity anddefinition of both speech and music.Lobes from the speaker clusters re-flect off the ceiling and reflect backinto the seating areas. If the ceilingis acoustically absorptive then thefirst reflection off the ceiling will losemost of its energy before it reflectsits way back into the seating. Even ifthe ceiling is absorptive only in themid and high frequencies, this willstill help shape the reverberationdecay contour. Remember, if themidrhigh frequency energy is ab-sorbed on the initial reflection, thenregardless of the absorption coeffi-cien: of subsequent re2ections, themid/highs will not be reflected.Time/frequency/energy spectraldecay curves are a useful tool in an-alyzing the intensity, density, andspectral distribution of the early re-flections.

?YPICAL CEILING SURFACESCeiling surface materials are often

corrugated or perforated metal, or"acoustical" ceiling tile, althoughsprayed -on treatments are some-times used.

Cotrugated

Some mid -range diffusion occursdue to the shape, the absorption isnegligible. Glass fiber is often lo-cate) above the corrugated ceiling,but this only aids the thermal prop-erties.

Perforated Metal

Glass fiber is typically located be-hind perforated panels, but the per-brations usually account for lessthan 10 percent of the surface area,with only marginal absorption bene-fits.

Acoustical Ceiling Tiles

Conventional tiles have little ab-sorption below 1000 Hz, and gener-ally only fair characteristic in themid -band. If the material is less thanI -inch thick, it is not going to behigh:y effective.Plaster/Concrete

Some high -frequency absorption(especially from unpainted con-crete), but otherwise all energy willbe reflected.Spray -on Surfaces

Asbestos can still be found insound facilities, but are oftenpainted over to seal the material.Asbestos has been found to causecancer, and is no longer legal in newinstallations.

House sound systems often havelobes that reflect off the ceiling andback into the seating areas, degrad-ing the clarity and definition. Evenif constant directivity horns are usedin the house system, sound systemsbrought in by touring sound compa-nies are unpredictable. Crowd noisewill, of course, be totally unaffectedby whatever sound system is used,and a highly absorptive ceiling willhelp improve the signal-to-noiseratio of the room.

CONVENTIONAL ACOUSTICALTREATMENTS FOR THECEILING

Non -asbestos Cellulose Fiber spray-ons

These are cost-effective and havegood performance but care must beaken that fire code requirementsare satisfied. The ceiling must alsobe an appropriate substrate orchunks of the material may delami-nate. Ceilings that flex, such as mostcorrugated metal, are questionablecandidates for spray -on treatments.Good mid -bass performance re-quires at least 3 -inch depth, whichmeans multiple coatings will be re-quired. Proper resin content andcareful control of thickness is neces-sary to avoid serious maintenanceproblems. In warm and humid cli-mates where ceiling sweatin g is com-mon fungus and adhesion can beproblems. Assuming your installa-tion is appropriate forspray-ons, theonly separate low -frequency absorp-tion devices will be needed to pro-vide wide -band treatment. Spray -onmaterials can also be used for walltreatment, but they must be out ofreach as they are not robust to con-tact.

Glass Fiber

This is the commonly -known treat-ment, as it is relatively inexpensive,meets fire codes, and does not de-grade over time. The hidden cost isthat it is rarely usable without someadditional material fabrication such

as perforated metal (60 percentopen), or fire -retardant fabric cover-ing. One trick to keeping cost downis to use panels of semi -ridged, black-

dyed glass fiber, attached to the ceil-ing by bolts, with large (3 -inch)diameter washer to catch the mate-rial. If the ceiling is high enough, theappearance may be acceptable, theperformance is good, and the priceis right.

Like other surface treatments, ab-sorption for 3 -inch semi -rigid glassfiber falls off below a few hundredHz. Careful design of spacing thepanels slightly away from the ceilingcan improve the low -frequency char-acteristics through diaphragmic ab-sorption.Acoustic Foam

Various suppliers of acoustic foammarket convoluted or wedge-shapedpanels. For really effective absorp-tion into the voice range panel thick-ness should be 3 -inch or greater.

Most foams do not like ultra -violetor moisture. Non -bridging paintsthat offer improved fire retardingand better smoke spread ratings canbe applied. Halcon coatings areavailable to eliminate moistureproblems, but some high -frequencyabsorption is lost.

The big problem with foams arefire codes. Installations that requireover five -thousand square feet oftreatments or have a ceiling less than25 feet will rarely be acceptable tothe fire marshal.

Melamine Resin Foams

These materials offer superior ab-sorption characteristics (especiallybetween 250-500 Hz) compared toconventional foams, meet therigorous class I and ASTM-E84 fire-

code specifications. The price is al-most ten times higher than raw glassfiber.

WALL PROBLEMSParallel Walls: Large expanses of

hard -surfaced parallel walls that arenot angled or splayed will create flut-ter echoes.

Curved Walls: Will refocus thesound creating uneven coverage andslap -back.

Most of the treatments discussedfor ceilings apply to walls, but noneof these surface materals are effec-tive below a few hundred Hz nor canthese materials be used within reach

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WIDE -BAND HIGH ENERGYABSORPTION DEVICES

Menlo Scientific Diaphragmic Ab-sorber

These devices are wall -mountedand are five -sided, with an off -centerpointed front section. Perforatedsteel screens are used (with optionalfabric covering).

Internally, a diaphragmic mem-brane is used to absorb low frequen-cies, and two -spaced layers ofsemi -rigid glass fiber absorb mid -

bass through the high frequencies.The glass fiber is spaced to aid low-

frequency absorption. The steelscreens work to diffuse whateverenergy is not absorbed. The con-

struction uses specially treated fireresistant wood.

RPG Abffusor

An absorber -diffusor for medium-sized facilities, high absorption isachieved down to 100 Hz when in-stalled with a 12 -inch air space be-hind the device. The device consistsof an array of wells of equal width,but different depths, separated bythin dividers. The well surfaces anddividers are fabricated from a porousabsorptive material.

Menlo Scientific Cylindrical- Ab-sorbers

Cylindrically -shaped Helmholtzresonators 2.5 feet in diameter andsix feet long are used to provide low-

frequency absorption. Slots cut intothe 6 -foot tube provide low -frequency absorption. Glass fiber on

the inside of the wedge and 3 -inchthick wedge-shaped acoustic foamon the outside provide aperiodicdampening of the resonator Q so al-most an octave of absorption isachieved. The tuning of the cylindersis staggered so when multiple unitsare used, absorption is effective be-tween 20 and 200 Hz. Above thisrange the absorption is crossed overto the acoustic foam on the surfaceof the tube. The foam is a specialmelimane resin that meets theASTM-E84 Class I fire code stand-ards. The foam is cut to a 3.5 -inchdeep wedge contour. The cylindricalabsorber has been engineered to dif-fuse whatever energy that it has notabsorbed, although its absorptioncoefficient is close to 1 over the midand high frequencies. Elb

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COREY DAVIDSON

On Tour with the Dixie Dregs

The subject of this story issound reinforcement. Rein-forcement simply means,according to Webster's:"...the action of strengthen-

ing, making stronger or more pro-nounced."

Notice how there is nothing stated inthis definition that implies an altera-tion or change in the structure of there-inforcee. One definition that I like is: lbmake bigger than life. Bigger is prob-ably the best way to describe it.

The problem is that the reinforce-ment of music is not easy. The soundengineer is at odds with many variablessuch as the size of a room and its acous-tics (reflections, dampening, reso-nances, traps, decay times, directivity,dispersion, nodes and diffractions, notto mention the ominous eighth space)that will all have a direct impact on thequality and intelligibility of the music.

However, this story is not aboutacoustics. It's about the musjk and theway that it comes across to iffEstener.

Corey Davidson is Technical Editor ofdb Magazine.

Sure...it is very important to under-stand acoustics, but an understandingof music is what lies underneath all ofthe technical jargon.

When you combine the dynamicrange of the New York Philharmonicwith the electrical power of Van Halen,then fold in the musical styles of jazz,country, classical and rock, you willmost likely come up with the music ofThe Dregs (alias The Dixie Dregs).Many believe that the music of TheDregs is some of the most challeelectric music available toda hat agood basis upon which to- lish astory about sound reinforcement.

g

THE DREGS

Our literview is with sound en-gineer/system designer Ken Hirsch.Ken tells me, "This band (Dregs) is oneof the most deing groups of ar-tists that I ha ever worked for. Thesemusicians are the pinnacle of their re-spective categories in music. They haveall won awards (and Grammy nomina-tions) for their instrumental prowess,both individually and as a band."

Figure 1. Ken Hirsch with Shubert Systems Group equipment.

I certainly shared those perceptionsfor I had worked as synthesizer pro-grammer for T Lavitz (Dregs' key-board player) both before and afteihismembership in theApand. My job inthose days was to recreate soul 1s thatT was interested in having on his syn-thesizers. He would bring me tapes ofother bands and ask me to get thesounds that Keith Emerson, HerbieHancock, Jan Hammer or Chick Coreawere getting on their 'nths. Some-times T and I would sit for hours tweak-ing in sounds that he envisioned in hismind's ear. When he changed over toanother type of synthesizer, I had toaurally duplicate those sounds on thenew synthesizer. Then and now, TLavitz is one of the more fastidioustalents today. Since those earlier days,interfacing and RAM have made pro-gramming much easier and T Lavitzhas come into his own as a renownedsynthesis). lbgether with his fellowDregs, they have brought to the worldtheir own special brand of classically-coulitified, fusionesque, instrumentalrockfind roll.

On a Saturday in July of this year, Iwent to see my friends play one of theirta.st shows as a band. Steve Morse hadjust finished a stint as a commercial jetpilot and T Lavitz had contacted theband members for a final reunion. Myearly arrival enabled me to sit througha sound check...a situation that manyfind boring. I had the opportunity ofhearing the band many times in thepast, but I now found myself mesmer-ized by a drum sound -check. Rod's kitsounded so tight and I know that he is astickler for great kit sounds. However,the sound out of the P.A. was record -like. Now I had heard many shows atthis particular club (including havingplayed there myself) and the house sys-tem had not been modified in any wayfor this show. I thought that the soundengineer must have been using trig-gered samples of great drum sounds aswell as the sound of the kit. I was cer-tainly mistaken. This incredible drum

Figure2 The house system at the Rancus night club.

sound was just the drums. I now knewthat I had to have a chat with theirsound engineer. Anyone who can getsuch great sounds must know some-thing worth sharing.

PERSONALLY MODIFIED GATEI met with Ken on Friday, August 19,

another one of the Dixie Dregs' lastNew York appearances. It was beforetheir final show at a venue called Sun -dance, in Bayshore, Long Island thatKen expressed his deepest thoughts onsound reinforcement and shared one of

Figure 3. The 24/16remote recordingvan owned by Den-nis Dragon.

his design -modifications of an audiogate.

What kind of modification did youperform on what gate? "An old Om-nicraft GT-4 was the gate that I mod-ified. About four or five years ago thisgate was available for around$249.00...one of the lowest -cost gateson the market. I had gotten particularlyfrustrated with them because they wereonly an on/off gate. I needed a way tocontrol the amount of gain -reduction.I decided that I should simply try to sellthe gate and purchase the unit withwhich I would be happier. I becameeven more frustrated when I tried tosell it because nobody wanted this gate.Even when I got a bite and somebodywould come and see it, they would re-ject the unit for either not having thefeatures of gating that they wanted, orthat the connectors on the back wereundesirable, or both. I now had to de-cide whether or not to trash the unit orget my dollar's worth by modifyingit...providing that the modification wascheap."

"The gate had THRESHOLD andRELEASE time. What I wanted to dowas to control the amount of gain re-duction so that with one knob, I couldset the unit wide open for setting up thegates. This way the THRESHOLD wasalways set and I could open up the gateto get it out of the way. Then I couldtake the new gain reduction controland turn it down to various amounts ofgain reduction so I could drop down 10dB for just ducking. With my modifica-tion, the gate became a ducker in addi-tion to being a straightforward noisegate."

Let's describe to our readers a littlebit about the principles and operationsof a gate such as: the advantages ofusing gates, and how they are applied.

"Ninety-nine percent of the time Iwill use gates on tom-toms. lb get torn -toms right in the mix, they have to beespecially prominent, because whenthat drummer hits them, you wantthem to jump out. Generally speaking,when a drummer goes for tom-toms, heis trying to make a point, so as a soundengineer, you want them to be right up-front in the mix. lbm-toms are a drum-mer's way of getting a few licks in muchthe same way that a guitar player getshis licks in. They often occur betweenvocal parts. In between vocal passages,a drummer will throw a few licks in justto accentuate his parts rather thanplaying the straight beat. So I generallybring the toms up. However when you co

..,

0

bring the toms up in volume withoutgates, all the extraneous noise that is onstage or near the drums will beamplified as well as the sound that youwant in the miss. This extraneous noisewill mess up the snare's EQ, the cym-bals, and will add unwanted sounds."

Does the fact that you use gatesmostly on tom-toms mean that you tryto avoid the use of gates in other areas?"If I've got it available, I like to use gateson kick -drums. Occasionally it reallyhelps to tighten things up. I certainlyshy away from using a gate on a snaredrum. Most drummers that I work withare sophisticated enough to play para-diddles and second -line beats, and allsorts of wild stuff that a gate wouldchop up. The basis of a live rock bandcomes from where the drummer isgoing. In other words, the rest of theband is responsible for shaping themusic around the rhythm. Now thisstatement might get me into hot waterwith lead guitar players, keyboard play-ers, and bass players, but let's faceit...drums are a priority. A poor drumsound can destroy the overall sound ofa band. There is so much enharmonicinformation in drums that they caneasily become too cumbersome andoverbearing. If anyone doubts that, allthey have to do is listen to any record inpopular music. It will be quite clear thata good drum sound can help to definethe direction of the music."

us about this tour. "Everywherewe have played (worked) I have had todeal with the house systems. We are notcarrying our own P.A. Actually I'm notdoing as bad with this tour as with theBlues Busters."

Who's in the Blues Busters? "TLavitz (from The Dregs), Larry Zack(from Jackson Brown and Rare Earth),Freebo (from Bonnie Raitt's band),Catfish Hodge (singer), and PaulBarrere (from Little Feat). The currentline-up has replaced T. Lavitz and PaulBarrere with Brian Auger (BrianAuger's Express) on keyboards, andLeo Nocentelli (from The Meters).The venues that were booked for TheBlues Busters were lousy clubs withterrible PA. systems. Basically, thatwas a band of great musicians that hadto play in crummy rooms. The tour wascertainly a challenge because I had torepresent the band to theaudience...and the audience is not in-terested in excuses as to why the soundsystem might be deficient. Those kindsof gigs are the ultimate challenge.Nothing is more satisfying than to

squeeze the most that you can out ofminimal gear. Sometimes, having to dothat will bring you back to the basicsthat one must never lose sight of."

"This tour with The Dregs is beingbooked in venues that have adequatesystems, however, it's not easy to use adifferent system every show. The onlyadvantage is that the PA. is already inplace...a luxury that I gladly would for-feit in order to use my own system. Butagain, on this tour, we had no choice."

USING HOUSE SYSTEMS

Tell us about your own system. "Mysystem is presentl in a night club called'flancas in Mali , California. Thatsystem consists of eavey 1608 moni-tor console, MXR EQs, and Peaveypower amps. There are other assortedbrands, none of which are ultra high -end brands. The funny thing about thatsystem is the fact that it's piecemeal.Most of what I have is quite atrdableto the average person. GeneMly, mygear is all used and has come second-hand from bands and sound compa-nies."

Do you have brand -name choices?"Not really. I mean, I certainly knowwhat the high -end gear is, but I knowthat for live sound, headroom ieby far,the most important factor. As matterof fact, it is how well one underkandsheadroom that enables the eneer toget the most out of a systpat. Beefytransformers (heavy and yell-wound)and good power supOts are at theheart of good elect hies. With a littleinvestigation, on n learn about whatis in a power ply and immediatelybegin to a that knowledge to theunderst. , purchase, and use ofequipmen

What is the aveMillize room thatwe're dealing with in this dIstliqpn?"Generally 500, 600 seat venues."

GAIN STRUCTURES

How much power do you hope to runin rooms that size? "For those sizedrooms I would hope to run at least5,000 to 7,000 watts or more."

How much of that available power doyou actually use? "Depending on thegain structure, 9 times out of 10, I'musing almost all of the amp's availablepower. But I never attempt to clip theamps. The key is to have enough head-room so that you never have to heatthose amps up to the point where theyare struggling or it will show in themusic. You want enough headroom sothat it can be as loud as you can stand it.

If the band is good and you have doneyour homework in terms of room EQand gain structures, it can be prettyloud and pleasurable."

Could you elaborate on what youmean by gain structures? "One mustlearn from experience how preampsreact, and which mixing boards cantolerate a clipping indicator that is onat a steady beat and which ones won't.Another key is to get the subgroups andthe output masters so that you're notdriving one or the other too hard. Someboards will indicate a clip to the inputof a bus. This is possible as opposed tothe indication of output bus clipping.As you pile on gain from the individualchannel faders, you can clip the input tothe bus. One must be very careful andlearn to understand the way in whichindividual pieces of equipment achievegain."

"Once you have looked over theblock diagrams of two or three mid-range 24x8 to 32x8 channel consoles inthe 10,000 to 20,000 dollar range, theystart to look very similar. It becomes amatter of your skill in recognizing eachconsole's limitations and its charac-teristics of overload. There are someeconomy boards on the market that arevery touchy and will go into clip when avery fine line is crossed. Others canseemingly tolerate hot signals that theboard s* as 'in the red.' A good ex-ample of these two conditions are theold Yamaha M1000 and a Yamaha2408. The P 000 was considered tobe, at one time, the absolute work-horse of the industry. With transformerins and transformer outs, its broad dy-namic range, LC type EQ, and superhigh output, the PM100gwas a difficultboard to clip. Signals could be placed inthe red without the slighted in-dication that clipping o d. Thiswas pattflidue to the elaborate inputpad design. The 2408, on the otherhand, is very sensitive to imp' rnstructures and one will find t -

denly, unless they know that particularconsole, clipping and distortion areeasily encountered. I'm not saying thatone is better than the other. On onehand the PM1000 might be desirable.On the other hand, the 2408 is far moreversatile in terms of patch -points etc.The point of all these comparisons is togive the engineer the ability to under-stand the situation at hand. We're talk-ing about making the most with whatyou've got."

Figure 4. The challenge presented by a large band of horns. An array of horn play-ers mired by Ken Hirsch. The photo includes players from Tower of Power, MadDogs & Englishmen, Rod Stewart, Ricki Lee Jones, Disney sound trackorchestras, and Bany Manilow.

"A good rule of thumb is to look at thepower ratings of a given piece of equip-ment and realize that the manufacturergenerally under -rates. This can be to asound engineer's advantage in order tofind new levels and limits. Manyspeakers can take two and three timestheir rated power limits. I have neverblown a speaker from too much cleanpower. You can. But what I'm saying isthat distortion from clipped signals willdo far more damage, even at lower

levels, than just too much power. Clip-ping will cause things to heat upsooner. Clipping at high power levels isdisaster...both for the equipment andthe listeners!"

When it comes to reinforcement,there are so many factors that will af-fect the delivery of sound. A differencebetween 16 kHz bandwidth and 20 kHzbandwidth will not make or break ashow. Ken adds, "If I were to compare aPeavey stack, properly set up and prop -

Figure 5. The final version of the Onznicraft GT-4 modification.

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erly powered, to a JBL stack, properlyset up and properly powered, thedifferences are minimal."

"The real test is to be thrown into asituation with nothing but your handsand the gear that they throw at you, andstill be able to pull -off something thatreally sounds good. That is the mark ofa truly good sound engineer. It's im-pressive when someone can walk up toan entire system that they have neverseen or operated before and make itsound as good as someone else whoowns the gear."

INSTRUMENTAL VS. VOCAL

What's special about sound for TheDregs and is there an advantage to thefact that they are not a vocal band?"Equalization for a vocal band as op-posed to equalization for a purely in-strumental band are two completelydifferent animals. In reinforcing avocal band, one must leave a hu-mongous amount of gain and band-width for the vocals. You must clearaway a lot of the frequencies of the in-struments that would override or inter-fere with vocals. With instrumentalmusic you've got the entire bandwidthto fill up with all the various instru-ments."

Do you prefer one over the other? "Ilike both. When I first started out doingmusic, I worked with primarily countryand country rock bands. I cut my teethworking with bands that had four andfive vocalists and learned to run the en-tire band with one hand, and all the vo-calists with the other. I actually hadeach finger on a vocalist. Instrumentalbands are refreshing in that you canconcentrate on instruments and letthem be the stars."

How is recorded music and its livecounterpart related? "Live music is es-sentially an exaggeration of what youhear in recorded music. The vocals willbe louder. The drums will have moredynamic range and will jump out. Theleads will be louder. You're really exag-gerating the truth that the recordstarted out with...at least that's the waymy philosophy works in mixing. Thebottom line is that you're cutting a fineline between truth and a charac-terization in order to bring out thehighlights and make them clear to a liveaudience."

"When a guitar player walks up to thefront of the stage and starts wailing, theaudience expects it to be bigger thanlife. lypica lly, on a record, the guitar (atthis same point in the music) would be

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mixed back in so that it blends becausethe definition of the average homestereo system is considerably betterthan a live PA. system. In the homestereo context, you're not working in ahostile environment like arenas, highschool gymnasiums, field houses, etc."

How do you feel about real-timeanalysis of a space, either before orduring a performance? "I've triedRTAing rooms. First of all, it annoyseverybody involved because you needthe room to yourself with thishideously loud-wooshing pink -noiseassaulting the ears of anyone within thespace. RTAs are effective to a certainpoint but they don't tell you the im-pulse response of a room."

Explain, lease. "When a snare drumis hit hard the room responds in a verydifferent way then when a singer sings anote. So there is an impulse and asteady state signal. A steady state signalwill eventually fill a space and build upnodes. An impulse sound will smackstraight out into the hall and bring backcertain resonant frequencies. Gener-ally, pink -noise analysis will show youwhere the room is building up nodes,but those nodes interact and create newnodes."

"An Ip'A is a wonderful tool...if youcan learn to ignore it when you have to.It's like having an oscilloscope for ana-lyzing waveforms...it's wonderful if youneed it. When you're doing micro-scopic analysis, scopes and complextest equipment can certainly help to ex-plain and correct problems. Thosepeople who have vast experience inelectronics know that you can get awaywith just a volt meter and get 90 percentof what you need to know. The voltmeter in this discussion could beanalogous to your ears and the meterson the console. Personally, I own aGold Line 30 real-time analyzer. Themic that I use with it is not the cali-brated mic, but it's a mic whose charac-teristics I know, and it can take gettingbeaten and stepped on. If I see (hear)anomalies that are boggling my mind,and I find myself groping in the dark forEQ, the RTA can help find an answer."

answer your question as towhether or not I use RTAs, I really don'tbelieve that it offers me an advantage. Iprefer to start with an album or recordthat I have played on my own, personalstereo system. If you take a CD and put

it in anyone else's CD player, it's goingto sound different. CD players varyfrom one make and model to anotherbecause of the differences in A/D, D/Aconversions, and filtering. So I refer-ence P.A. systems with what I know I'mfamiliar with in a previous controlledenvironment. If I know what it shouldsound like on my personal system, I cantake that same material and go for asgood a duplication of playback aspossible on a P.A. system."

HANDS-ON SUGGESTIONSDo you have any suggestions as to

how a beginner might become familiarwith reinforcement in a hands-on con-text? "Start working in a local club on aregular basis, or start workjpg for asound company. Now I know that thismay sound like one has to be a gruntand sweep floors, but sometimes wemust all pay a price to get to the nextlevel. If you want it, it's always worth asacrifice. It is very important for thebeginning engineer to work with noth-ing (as little as possible). No gates, nocompression. Learn how to ride vocalsby hand. Ity to familiarize yourself withas many process, devices as youcan...although that's becoming im-possible...I don't know half of them atthis point in time so I try and stay withthe ones I know. 'fly learning how tomix and work without aids or luxurytools. Don't go out and buy a pile ofgear and then sit there and spend all ofyour time learning how to operate itwhen your priority should be what theband sounds like."

For our techy friends out there, let'slook at your gate modification (Figure1)."A reverse -log or audio taper poten-tiometer is the pot of preference forthis gain modification. I used an RV5pot, which is a very small pot that hasthe leads coming off the back. If theleads were to have come off the side, itwould have interfered with the pot inone direction and with the case in theother direction. It is necessary togenerate a voltage divider around thispot. The top 680 olun resistor drops thevoltage down from +V so that theemitter of the transistor is not pushedtoo hard. The LED in the opto-isolatoris also protected by the drop in + V. The2k resistor biases up from groundenough so that the voltage potential isnot dragged down too far. Basically, 2kohms is where I get no more of the

ducking effect...so that is essentially in-finity."

"The diode (1N914) prevents an im-proper voltage feedback. This diodesits between the LED of the front paneland the emitter of the 2N3904. An ele-gant aspect to this design is that theaudio path is traveling through only anL -pad. One part of the L -pad being theopto-resistor and the other part of it isa 10k resistor to ground, which essen-tially gives you a variable L -pad. Whenthe opto-resistor is totally on, you havezero attenuation. As the LED in theopto-resistor dims out, it increases inresistance and turns into an L -pad ofincreasing attenuation until infinity isreached. This is how gain reduction isachieved without the use of an activecomponent...like in a VCA, whichwould drastically increase the cost ofthe modification."

"The added bonus is that the LED onthe front panel follows the amount ofgain reduction, so as you turn the gainreduction to increasingly lower levels,the LED on the front panel will lightup, indicating that you're ducking alittle lower. When the LED is fully lit,the gate is wide open. As you dim itdown, it will indicate the reduction.When the gate opens, you'll see theLED get brighter. Again this is a verysimple modification that helped savethis piece from atrophy. The most diffi-cult thing here is drilling a hole in thefront panel and charting your amountof gain reduction, which I did with astandard loss meter that I got from alocal telephone company."

In closing, Ken adds a strong voice ofinspiration, "One of the things thathappens to many people as they be-come exposed and involved with thispart of the industry, is that they dis-courage themselves by saying: `...it's sodifficult and complex!' But it's not thatcomplex. Think about magic. You lookat a magician and he does this in-credible trick. You're sitting theretotally amazed, wondering how it wasdone. For the few people who have ac-tually learned how the trick was done,they are surprised as to how easily thetrick is accomplished. It's always amaz-ing and awe inspiring until you knowhow it's done. Sometimes you canamaze yourself when you get good.Some of audio's best tricks are simpleand yet so deceptive."

Conceit LoudspeakerProcessors

Due to the ever-increasingpublic awareness of soundsystem fidelity, the pro -user's desire for depend-able and "idiot -proof'

audio equipment, and the loud-speaker manufacturer's constantbattle to be one step ahead of thecompetition, the age of the concertloudspeaker processor has arrived.

Apogee Sound, Community Lightand Sound, Eastern Acoustic Works,Electro-Voice, Meyer Sound Labora-tories, Professional Audio Systems,and Renkus-Heinz are but a few of thecompanies presently manufacturingprocessor -based concert loudspeakersystems. Each company has their owndesign philosophies and individualproduct features, but as a whole, pro-cessor -based concert loudspeaker sys-tems share the same general objectives.This article will attempt to explicatethe most common design objectivesand lightly touch upon themethodology in which the manufac-turers are attempting to achieve thedesired results.

The concert loudspeaker processor,in many instances, is nothing morethan a combined electronic cross -over,signal delay, speaker protector, and re-sponse corrector packaged togetherfor a particular loudspeaker and placedinside a single rack -mountable box.The objective of the loudspeaker pro-cessor is to optimize the acoustic out-put of the loudspeaker whileprotecting the loudspeaker com-ponentry, all the while trying to remainas transparent as possible throughoutthe dynamic range of the loudspeaker.It seems simple enough, but applyingthis philosophy is extremely difficult.However, aside from the difficulties indesign, the manufacturers are develop-ing loudspeaker systems with definiteadvantages directly resulting from theloudspeaker processing.

Aside from the obvious size and con-venience qualities of the processor,there are a couple of other benefits aswell. For example, by placing all of theworking components in one box, andapplying the same design philosophythroughout the entire unit, the proces-sor is apt to be much quieter than in-

dividual components strapped to-gether. As an aside, the technician'stime can be spent in other places ratherthan patching together outboard com-ponents while trying to figure out inputand output impedances. An additionalbenefit is the manufacturer's ability tocustomize the processor to a particularloudspeaker. Herein lies the realpower of the concert loudspeaker pro-cessor.

By designing a loudspeaker processorfor a specific loudspeaker, the manu-facturer is able to incorporate circuitryfor a known sound source to achieveoptimal performance from that soundsource as well as protect the soundsource with the use of protective cir-cuitry. The net effect is a seeminglymore efficient loudspeaker systemthan traditional loudspeaker systems.As mentioned previously, the majorityof the processed loudspeaker systemsperform these optimizational func-tions with the use of electronic cross-overs, signal delays, speaker protectioncircuits, and equalization or speakerresponse correction circuits. The nextfour sections will touch upon thesefour functions of the loudspeaker pro-cessor.

ELECTRONIC CROSS -OVERSThe electronic cross -over in loud-

speaker processors is much the same as

Figure 1. A loudspeaker in or out ofphase.

LCLOSPEhlriIN RELATIVE

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ANDREW T. MARTIN

other electronic cross-overs. Thedifference lies in the manufacturer'sability to design cross -over frequen-cies, slopes, and phase to meet theneeds of the loudspeaker in order tocreate the optimum performance. Thisobviously cannot be accuratelyachieved with off -the -shelf cross-overssince the manufacturer has no way ofknowing with what sound sources thecross -over will be in line.

The loudspeaker processor facilitatesprecise tailoring of the adjoining cross-over frequencies to the specific soundsources they are serving, thus creating asmoother transition from soundsource to sound source assuming thespeaker components are chosen prop-erly. The smoother transition gives theloudspeaker the illusion of being onlyone sound source rather than multiplesound sources working together, againassuming the speaker components arechosen correctly.

Cross -over slopes can be designed tomake the transition from sound sourceto sound source longer or shorter, de-pending on the response output of theloudspeaker as a whole. Combinationsof different cross -over slopes are alsoused to generate the desired resultsfrom the loudspeaker components.

Finally, phase can be adjusted foreach cross -over frequency in order toalign the acoustic wavefronts of thetransitional sound sources. Alignmentis achieved by matching the acousticphase of the first sound source with theacoustic phase of the second soundsource at the cross -over point, therebyputting the two sound sources in thesame relative phase (Figure 1). Acous-tic wavefront alignment is important inorder to reduce the cancellation andsummation of the acoustic energybeing emitted from the loudspeaker. Itis important to note that two soundsources with different coverage pat-terns, although in relative phase on -axis, will not remain in relative phasethroughout their off -axis coverage pat-tern due to the difference in flare ratebetween the two sound sources. Theproper choice of loudspeaker com-ponents is imperative for a successfulloudspeaker, even with a loudspeakerprocessor.

Figure2 Signal synchronization.

ca

Figure 3. Signal delay.

Loudspeaker with signals synchronized.

Same loudspeaker without signal synchronization.

'linear graphs

1014sec. delay

signal delay circuitry

no delay

20 tAsec. delay

*Note: It is important not to bypass

the signal delay device with any

source signal due to the inherent 50

to 60 micro second delay the A to D /

D to A circuitry requires.

The "no delay" signal path is therefor

a reference signal, and not a true

0 micro second delayed signal.30

-1020

micro seconds of delay

Signal delays are utilized for soundsource signal synchronization, a vitalfunction in processors if the processor

is servicing a loudspeaker with non-aligned sound source acoustic centers.

The acoustic center of a sound sourceis the point at which the acoustic

energy appears to originate, and thispoint does not have to be in the centerof the magnet assembly or in the throatof a horn. If the acoustic center of one

sound source is not in physical align-ment with another sound source, un-natural filtering effects will occurbetween the acoustic outputs of thesound sources. The filtering is com-monly known as comb filtering (Figure2).

Comb filters, when sizeable, willcause an audible distortion to the pro-gram material, and can be easily de-tected. However, comb filtering oftenwill not be heard directly from theloudspeaker. Instead, the resultant ofcomb filtering will be heard in the en-vironment surrounding the loud-speaker due to the adverse combfiltering effects on a loudspeaker'scoverage pattern. A loudspeaker withsound sources that are not signal syn-chronized can emit very concentratedlobes in odd directions. Not only doesthis make loudspeaker placement diffi-cult, due to feedback control, but it willalso cause an increase in the reverber-ant field resulting from unwantedroom reflections-thereby decreasingthe direct to reverberant sound anddecreasing intelligibility.

Since, as mentioned earlier, theacoustic wavefronts of the soundsources must be in alignment, and nowthe acoustic centers of the soundsources must also be in alignment, themanufacturer of the loudspeaker sys-tem must make a few decisions. Mostmanufacturers will physically align theacoustic wavefronts, and then intro-duce signal delays in order to synchro-nize the signals of the loudspeakersound sources (Figure 3). Other manu-facturers will develop an integratedsound source array that physicallyaligns both the acoustic wavefronts andacoustic centers, thereby eliminatingthe need for signal delay circuits insidethe loudspeaker processor.

SPEAKER PROTECTION

The most common form of speakerprotection in loudspeaker processorsis achieved with limiting. The limiterwill "squash" the dynamics of the pro-gram material, through the use of a veryhigh compression ratio, should thelimiter be switched on. The manufac-turer can design the limiter in such away that the switching circuitry andcompression ratio are suitable for thespeaker components inside the loud-speaker, and the dynamic range of theloudspeaker is maintained with thehighest level of processor trans-parency. The method of triggering the

limiting circuitry varies from manufac-turer to manufacturer.

Some of the loudspeaker processorscontain "sensing circuitry" that willconstantly monitor the output of theamplification device and begin limitingwhen the amplifier goes into clipping.A very high -quality amplifier with themanufacturer's suggested power ratingis nerPssary for this type of protectionsystem to be of benefit. Other loud-speaker processors will incorporate athreshold gate that triggers the limiterwhen the program material exceeds thepre-set threshold.

Another form of speaker protectioncommonly found in loudspeaker pro-cessors is thermal protection. Thermalprotection circuits are usually a form oflow to mid ratio compression. As withthe limiting function, the thermal pro-tection is triggered in much the samemanner. Additionally, there are somemanufacturers that use "sliding cross-over" functions in their loudspeakerprocessors to protect against thermaloverload. This function changes thecross -over frequency of the soundsource in danger until it is able to safelyoperate in the wider bandwidth again.

SPEAKER RESPONSECORRECTION

Speaker response correction, orequalization, is incorporated into mostloudspeaker processors. The proces-sor package gives the manufacturer theopportunity to fine tune the com-ponents of the loudspeaker with greataccuracy to achieve the desired loud-speaker output response. Some loud-speaker processors offer switchableand/or adjustable equalization func-tions for use when the loudspeaker isarrayed or placed in acoustically cou-pling environments.

Additionally, some loudspeaker pro-cessor manufacturers include "feed-back suppression" circuitry with theirprocessors. When the processor sensesa feedback loop, the proper attenua-tion is applied until the feedback loopis repressed.The age of the loudspeaker processor

has enabled the sound system engineerto purchase a loudspeaker system withgood performance, compact dimen-sions,and consistent acoustical charac-teristics: the three ingredients neededfor successful performance. The pro-cessor -based loudspeaker systemshave made it possible to travel fromvenue to venue and have an excellent

idea as to how the sound system will re-spond at each site, while the timeneeded for set-up is, in most instances,greatly reduced. The loudspeaker sys-tem's owner has the piece of mind thatthe loudspeakers have a high resistanceto destruction due to misuse. However,there are certain drawbacks to the pro-cessor -based loudspeaker systems aswell.

The loudspeaker processor must beused in conjunction with the specifiedloudspeaker. Hooking up a processorto the wrong loudspeaker would prob-ably not sound very pleasant, and maydestroy the loudspeaker, althoughthere are some manufacturers with"generic" limiter -based processingunits that are capable of operating withother manufacturer's products.

The loudspeaker processor also has atendency to distort the tonal values ofthe program material when the protec-tion circuitry is employed. However,the tonal variation due to the protec-tion function is usually much less de-tectable and preferred over the harshdistortion of over -excursion.

And finally, the purchase price of pro-cessor -based loudspeaker systems isextremely high when compared to con-ventionalthe value-that is for the individual todecide.

Manufacturers Mentioned:Apogee Sound, Inc., CA (707) 778-

8887, Community Light & Sound, Inc.,PA (215) 876-3400, Eastern AcousticWorks, Inc., MA (617) 620-1478 , Elec-tro-Voice, Inc., MI (616) 695-6831,Meyer Sound Laboratories, Inc., CA(415) 486-1166, Professional AudioSystems, Inc., CA (213) 534-3570,Renkus-Heinz, Inc., CA (714) 250-1035

A special thank you to Ken DeLoria,Apogee Sound, Inc.

Thank you, too:

John Wiggins, Community Light &Sound, Inc.

Ken Berger, Eastern Acoustic Works,Inc.

Joe Katowich, Electro-Voice, Inc.

Drew Daniels, JBL Professional

John Kirkland, Professional AudioSystems

Russ Farrell, Renkus-Heinz, Inc.

Gerry Ilchetter, Yamaha Corpora-tionofAmerica

JOHN EARGLE

co

System Intelligibility Criteria

This article is Chapter 12 of the author's new book "Handbook of Sound System Design," now publishedby ELAR Publishing Co. Inc.

INTRODUCTIONThe intelligibility of speech is of paramount importance in

public meeting places and auditoriums, and sound rein-forcement systems should always be designed with the goalin mind of increasing intelligibility over that afforded by un-amplified speech. The most important factors in determin-ing speech intelligibility are:

1. Speech level and signal-to-noise ratio. Speech can be un-derstood over a wide range of levels; however, at lower levels,the signal-to-noise ratio must be of the order of 25-30 dB ifspeech is to be clearly understood. At higher speech levels, alesser signal-to-noise ratio will often suffice.

2. Reverberation time. If the reverberation time in the 500Hz to 2 kHz range is of the order of 1.5 seconds or less, thenit will not decrease intelligibility. In fact, a reverberationtime of 1.5 seconds or less is generally beneficial, since it in-creases the level of speech without interfering with the artic-ulation of individual speech syllables. (The nature of thereverberation may be critical; in particular, strong discreteechoes will make for poor intelligibility if they are noticeablydisplaced from the direct speech sound source.)

3. Direct -to -reverberant ratio. For reverberation times inexcess of 1.5 seconds, the overhang of sound tends to blurspeech. In a sense, the reverberation behaves like a kind ofnoise signal, one that rises and falls with the level of speechitself.

-15 -12 -10 -5 0 5 10

Octave band signal-to-noise ratio (dB)

4. Subjective considerations. There are both good and badlisteners and talkers. Given the same acoustical environ-ment, an experienced talker will adjust his delivery to theconditions at hand, and he will be more clearly understoodthan an inexperienced talker. Likewise, an attentive listenerwith normal hearing will be at an advantage over an elderlyperson with some degree of hearing loss.

MEASUREMENT OF SPEECH INTELLIGIBILITYThe traditional measure here is syllabic articulation test-

ing. In such tests, a reader calls out a list of unrelated mono-syllabic words, and listeners at various parts in an auditoriumwritedown thewords as they perceive them. The articulationscore is simply the percentage of syllables correctly iden-tified. If a given listener correctly identifies 85 percent of thetotal number of syllables, then he will be able to understandnormal speech in the testing environment with an accuracyof 97 percent or higher, due to the contextual nature ofspeech. If his articulation score is 75 percent, then he will beable to understand approximately 94 percent of the words innormal speech. This latter condition may be generally satis-factory, but some extra measure of attentiveness on the partof the listener may be necessary as well.

FSTIMATING SPEECH INTELLIGIBILITYWhat the designer of sound reinforcement systems re-

quires is a method of estimating speech intelligibility beforea system is designed. Armed with such knowledge, he can de-termine just what kind of system may be best for a given en-vironment.

Articulation Index (AI)

15

0 35

0.30

0.25

0.20

0.15

0.10

0.05

Figure 12-1. Calculations of theArticulation Index (AI).

Figure 12-2 Sample speech and noisespectra: AI calculation.

Figure 12-3. Acomparisonbetween AI andsyllabic testing.

100U

0

13a) 60

5,

Zr) 20

0

80

40

Words insentencecontext

50

a 40cn

30

0l125

Long-term average male speechspectrum at 3 meters (10 feet)

RMS noise spectrum

Al calculation:Hz250 = 0.03500 = 0.081K = 0.162K = 0.184K = 0.13

Al = 0.58

Randomsyllables

0.2 0.4 0.6 0.8Articulation index

Figure 12-4. Articulation loss of consonants. 10.0

8.0

4.0

2.0

1.0

250

1.0

500 1K

Frequency (Hz)2K 4K

As an example of how to calculate AI, let us assume noiseand RMS speech spectra as shown in Figure 12-2. Each bandis individually observed,a nd its RMS signal-to-noise ratioentered into the graph of Figure 12-1. A line is drawn upwardfrom this value until it intersects the diagonal line repre-senting the octave band of interest. Then, a line is drawn tothe right, intersecting the vertical axis. Each contribution, asmeasured on this axis, is noted, and they are summed to givethe Al.

AI calculations are most applicable to non -reverberantconditions, such as those found in open-plan offices andmany paging applications. There is generally excellentagreement between AI calculations and articulation tests

Questionable

0.-515

Probable articulation loss of consonants (percent)15 10 5

Excellent

One of the earliest methods of determining the intelligi-bility of a transmission system is through the calculation ofAI, as developed by French and Steinberg and later modifiedby Kryter. In calculating AI, the spectrum of ambient noisein the listening space must be measured, either on octavebands or one-third octave bands, over the range from 250Hzto 4 kHz. Speech peaks are also measured over the samebands, and the two are compared at each frequency center.Figure 12-1 shows a method for arriving at the contributionof each octave band in determining Al, as suggested bySmith. In using this graph, octave band RMS speech -to -noise ratios are measured and are individually weighted fortheir contribution to the Al over the normal 30 -dB dynamicrange of speech. Since it is easier to measure the RMS valueof speech signals than peak values, it is this signal-to-noiseratio that is plotted in the graph. The assumption is madethat peak levels of speech are some 2 dB higher than theRMS levels.

-10 -5Direct -to -reverberant ratio (dB)

made under these acoustical conditions.

Figure 12-3 compares Al with several measures of speechintelligibility. In general, an AI of 0.3 or greater indicatesthat general speech intelligibility will be adequate.

0 5

Peutz's Articulation Loss of Consonants

AI calculations have been found to give erroneous resultsif they are made under reverberant conditions. Peutz sug-gests a measurement of the articulation loss of consonants asa determinant of speech intelligibility which takes into ac-count reverberation time, noise, and the direct -to -reverber-ant ratio in the frequency range of 1-2 kHz. can simplifyPeutz's method considerably ifwe apply it only in those caseswhere the noise floor is sufficiently low (30 dB below speechpeaks.) In this case, noise is not a factor in determining intel-ligibility, and Peutz's data can be replotted, as suggested byAugspurger, into the form shown in Figure 12-4.

0

100 -

80

60

40

20 -

Figure 12-5.Signal-to-noise(S/N) vs. speechintelligibility; thecurve gives thebest fit to datapoints (afterSmith).

-40 -20 -10S/N (dB)

In using this data, the reverberation time in the 1-2 IcHzoc-tave is measured or calculated, and the direct -to -reverberantratios at various parts in an auditorium are measured or cal-culated. The data is entered into the graph, and an estimatecan be quickly made of overall system intelligibility. Peutzstates that this method has a limit in accuracy of about 10percent, and it is for this reason that the data of Figure 12-4 isbroken down into only four broad zones of intelligibility.

The preceding methods are easy to work with, and they canbe imple- mented while a sound reinforcement system is stillon the drawing board if reasonable noise and reverberationtime estimates can be made. There are two other methods ofestimating speech intelligibility, but they require actualmeasurements on site. We will discuss them briefly.

100

80

60

40

20

-30 0 10

00 20 40 60 80 100

Signal retention (percent)

Figure 12-6.MTF vs. speechintelligibility: thecurve gives thebest fit to datapoints (afterSmith).

Figure 12-7. Permissible distances betweentalker and listener.

0.50

Lochner and Burger's Signal -to -Noise MethodLochner and Burger have determined that sound arriving

within a certain interval after the receipt of direct sound is in-tegrated by the ear and is useful. All sounds arriving afterthat time are considered as noise. The integration time is 95msec, and the expression for useful sound energy is:

95 ms

Useful energy =10 log f oc(p,t) p2 (t) dt

t =0

In this expression, a is a fraction of delayed sound, inte-grated taking into a ccount the direct sound and the delaytime.p(t) is the instantaneous sound pressure.

The signal-to-noise ratio is defined as:

95 ms

S/N =10 log J o oc (p,t) p2 (t) dt

p2 (t) dt

95 ms

Figure 12-5 shows the relationship between the S/N calcu-lation and speech intelligibility. Clearly, the method is an ac-curate one, but its implementation is quite complex.

Modulation Ransfer Function (MTF)Houtgast and Steeneken have proposed a method for

measuring the effects which reverberation and noise have onsignal integrity. Their method makes use of a test signalwhich is amplitude modulated and then reproduced in aroom. The effects of reverberation and noise fill in portionsof the modulation envelope, and the recovered signal can becompared with the original. In practice, a number of modu-lation rates are used at a number of one-third octave bands.Figure 12-6 gives an indication of the accuracy of the method,stated by Houtgast and Steeneken to be within 10 percent. In

INADEQUATECOMMUNICATION

c7 30 40 50 60 70 80 100

Figure 12-8. EAD vs. A -weighted noise level.6 - 20

5

4

in

a)E 3

w0

030

recent years, the RASTI (Rapid Speech Ti-ansmission Index)measurement method has evolved out of the work of Hout-gast and Steeneken.

PERMISSIBLE TALKER -LISTENER DISTANCES FORSPEECII COMMUNICATION

The graph shown in Figure 12-7 shows permissible talker-

listener distances as a function of noise level. The assump-tion is made that the listener and talker are not facing eachother. If they are facing each other, then the noise level maybe increased by 5 dB.

This graph clearly indicates the tendency of talkers to raisetheir speech level in the presence of noise, and continuedcommunication under elevated noise conditions is a strainon both talker and listener.

40 50 60

A -weighted noise level, SPL

1

70

15

10

5

0

aI

w

As an aid in determining operating levels for sound rein-forcement systems, the data of Figure 12-8 will be useful.Here, we have plotted workable speech levels, as a functionof noise level, for a raised voice (Curve A), a normal voice(Curve B), and a lowered voice (Curve C). In plotting thesecurves, the peak speech levels at a distance of one meter forthe three types of talkers were set at 70 dB, 65 dB, and 60dB,respectively. At lower noise levels, a 25 to 30 dB signal-to-noise ratio is maintained, while at higher noise levels the sig-nal-to-noise ratio is allowed to decrease.

This data will be useful in establishing a value for EAD, asdiscussed in Chapter 10.

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gadgets on hand? Many recordingstudios and radio stations are outfittedwith ramshackle, abused equipment.You may have yet to get your hands ondigital tape decks, high -quality delayunits, special effects boxes, and otheroutlandish audio playthings that wouldlet you run wild with exciting newsounds. But take heart: I produced amulti -layered, effect -filled extrava-ganza that bagged me a Clio Finalistcertificate when I worked at a radio sta-tion that had a decrepit stereo produc-tion studio. The place was equippedwith no more than a pair of Scully reel-

to -reels, two BE cart machines, and atired old Gates Executive mixing con-sole.

You see, at that time I didn't know anyreal people that were using betterequipment. lb me, all the fancy stuffwas just pictures in trade magazines. Inaively reckoned that if my fellowhelots were cranking out intricatecoups de maitre with similar gear, then Icould do it, too. You've seen the car-toons when somebody steps off a cliffand keeps right on walking, suspendedin mid-air until some spoilsport ex-claims, "Hey! You can't do that," caus-ing the unfortunate slob to plummet tohis violent doom. I was the one outthere hovering, but nobody had told mewhat I couldn't do yet. So, I set out toemulate that big station sound, and I'llshare some of the ideas I "invented." Ihope to spark your imagination andhelp you avoid re -inventing the wheel.

PRINCIPLE OF CLEANLINESS

First, a basic principle of audio pro-duction: The importance of cleanlinessin the studio can't be overstated. Elec-tronic devices are vulnerable to dam-age from airborne dust, soot, smoke, aswell as coffee, oils from human skin,food remnants, and many other com-mon substances. It's critical for you tokeep it as free of contamination as

possible. This means 1) Don't eataround the equipment, 2) Wash yourhands often, particularly after eating(and especially before editing tape),and 3) Don't place coffee mugs, sodapop cans, paper cups, beer bottles, orother beverage containers where theycan be slopped on equipment. Sure,you may set a cup down "just for a sec-ond," but it only takes one spill to shortout a circuit, coat a component withliquid, or allow a corrosive ingredientlike sugar or salt get on electronic partswhere it can slowly eat away at chips,solder, and wires.

Clean tape recorder heads before andafter each session. This helps assurethat if some lazy blockhead comesalong and neglects their cleaning du-ties, you'll have covered it. Also, ifyou're ever in a rush (it's been known tohappen), perhaps the serf ahead of youwill have cleaned the machines uponfinishing.

Since recording tape is simply a stripof plastic coated with billions of finemagnetic particles, it's logical to expectthat each pass through the head blockarea induces a small magnetic chargeon any metal parts in the vicinity.Magnetized heads and guides act like aweak version of the deck's erase head-when a tape goes by them, they tend toscramble some of the information onthe tape. Since the higher frequenciesjam more tiny signals on a given sectionof tape, they are the most fragile, andthus the easiest to destroy. If you neverdemagnetize your tape decks' heads,you will erase a few decibels of audiofrom your tapes each time you playthem. It's easy to prevent this.

Demagnetize the tape heads, guides,and metal parts in the tape path on eachdeck at the beginning of each day orcritical session. It only takes a momentto grab the hand-held head degausserand wipe away the built-up flux that canerase your tapes' high frequencies.


(Just be sure to clear the area of any re-corded reels or carts first.) Always dothe same thing to the capstan, guides,screws, or posts that also come in con-tact with the tape as it runs through thedeck.

EFFECTS TECHNIQUESOn to special effects. There are plenty

of home-grown techniques you can useto create a slew of interesting soundswhen you produce a radio commercial.

You can use a compressor/limiter tocreate special effects, such as simulat-ing the between -voice static heard ontwo-way radio conversations, or tomake your breath sound like DarthVader's. Play with it until you knowhow it works and what settings soundbest.You can also use EQ to create special

effects by shaping the sound to simu-late a tinny telephone conversation, atelevision speaker, or perhaps to imi-tate a robot voice.

Although your station may normallyair commercials in stereo for the sakeof hi-fi sound, you can take advantageof tape recorders that have two or morechannels to create interesting produc-tion effects. Prepare a script for twocharacters and take both parts yourself,reading one on channel 1 (leaving ap-propriate pauses), then recordingyourself on channel 2 as you listen tochannel l on headphones, and carryingon a two-way conversation with your-self. This is very easy to do if your tapedeck has a "sync" switch for playback soyou can reproduce the first channel'ssignal right from the record head, sincelistening to the playback head intro-duces a momentary delay that throwsoff the timing of the second voice. lbsound natural, practice leaving pausesthat are of just the right length so youcan slightly "step on" the first voice,meaning that you have voice #2 begineach line a split second before voice #1finishes. This sounds more like normalconversation. For a high-energydelivery, read a bit faster and step onthe voice a little more. This can be ef-fective if you read in the same tone ofvoice on both tracks.

lb sound like two different people,there are a couple of tricks you can try.If your tape recorder has a variablespeed adjustment or pitch control, youmight also record voice #1 or voice #2(or both) while running the tape re-corder at slightly different speeds. Inaddition, try reading in different voicesor playing silly characters to produce a

skit. Mix the finished two -channel tapedown onto a mono track on anothermachine while adding sound effects ormusic to the background.

You can generate echo effects byturning up a tape machine's playbackpot and feeding its output back into themixing board's inputs. The original sig-nal from your mic or other source firstgoes onto the tape via the record head,then is picked up a split second later bythe playback head. The slight intervalbetween the moment the tape travelsfrom the record head to the reproducehead defines the length of time be-tween repeats. limning up the tapeplayback pot too far, however, causesecho that gets too loud, distorted, ortinny.

An interesting variation is to use"pre -echo." This is done by recordingon one tape, flipping the tape over toplay it backward, and dubbing it toanother tape deck that you use to makeechoes. When you flip over this secondtape and play it back so the recordedsounds are again going forward, theecho now precedes the sounds.

You can generate another extraordi-nary tape effect by recording your voicenormally, flipping the tape over, play-ing it back in reverse, and recordingyourself on a second tape deck as youphonetically try to duplicate the gib-berish your voice renders on the back-ward tape. If you then turn the secondtape over and play it backward, you'llhear the words come out forward, andreasonably recognizable, but with aneerie, sort of otherworldly flavor. Youcan refute it with practice and if youdesire, combine it with EQ, echo, pre -

echo, and other modifications to createa strange sound that can suggest aliens,ghosts, or computers. Experiment byreading in a robot-like monotone,spooky moan, foreign accent, or someother vocal variation.

Playing with tape speed is fun, too.Most studio tape decks today havesome kind of variable pitch controlbuilt-in, but you can get unique resultsbywrappi ng your capstan wit h maskingtape. Cover it with one perfectlysmooth layer and you get a fairly steadyspeed. Make it warble by wrapping itone -and -a -half or one -and -a -thirdturns.lTy it on recording, playback, orboth. Fool around a bit, but be sure toclean the adhesive off the capstan whenyou're done.

These only scratch the surface of thewide variety of fascinating productiontechniques that you can use to produce

great radio commercials on a shoe-string budget and using the most basicof recording equipment. From elec-tronic cottage or backwoods radio sta-tion to world-famous recording orbig -city broadcast center anyone canget exceptional results if the peoplewho operate the equipment havelearned to improvise, experiment, andpush their technology to the limit.Your imagination is the most powerfulaudio production tool in the studio.

BEHIND THE SCENESAs I write this installment ofAd Ven-

tures, I'm sitting at my rickety desk sur-rounded by dozens of cardboard boxescontaining papers, office supplies,electric and electronic gizmos, me-chanical gadgets, certificates, photo-graphs, clothing, garbage, and evensome food. This miserable accumula-tion of rubbish constitutes the majorityof what one might call my material for-tune and worldly goods.

For reasons too complex to recountin this space, I have migrated again, thistime from Boulder County, Colorado,mountainous home of granola -munch ing college students and schuss-ing yuppies, to a quiet little rural townof 10,000 in southeastern Connecticut.Having left Careeraack Publicationsto form Porkpie Productions, I am nowa full-time writer, commercial pro-ducer, and entrepreneur.

Comments and suggestions from youare what keep this column alive, soplease write to me at P.O. Box 176, Col-chester, CT 06415 or in care of db, 203Commack Rd, Suite 1010, Commack,NY 11725.And now, the moment you've all been

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It's here! Hot off the duplicating ma-chines are the first copies of my long-promised audio tape program, How ToProduce Great Radio Commercials. It'sa four -cassette reference chock-full ofadvice, techniques, ideas, and tricks ofthe trade for anybody who wants tolearn more about putting togetherprofitable and award -winning radiospots. You also get to hear samples ofmy work, commercial parodies, andsome bonuses. Not sold in stores!Order your copy by sending check ormoney order for $99.95 (in U.S. funds)to Porkpie Productions, P.O. Box 176,Colchester, CT 06415. I'll provide freedomestic shipping. sib

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Of all the instruments known, noneelicits more opinions than the art ofmic'ing a piano. I have never seen moreopposite view points expressed bymore people, outside of politics. Oneperson's idea of perfection can beanother's idea of a nightmare.

One of the problems in discussingpiano mic'ing, and the advantages anddisadvantages, is that there is no com-mon consensus on what a piano reallysounds like. This is caused by the fact

that there is no agreement on where thelistener should be seated when listen-ing to the piano.

Some people prefer the sound whenthe piano is located on the stage andthey are sitting in the third to seventhrow of the theater, some people preferto feel as if they are sitting, playing thepiano themselves; while a third group

Pianos I Have Knownlikes the feeling of standing in the curveof the piano with the top open, watch-ing the player. Obviously, these threevery diverse opinions on how the pianoshould sound in the hall leads to veryunique concepts on how to translate apiano onto tape or into a PA. (Nevermind the additional effects of piano topopen, short stick or closed.)

DIFFERENT POSITIONSSitting in the audience creates the

Figure 1. Mic'ing a pianousing two micro-phones. The prima:), mic isover the strings about 2 -in.away from the main strutand 6 -in. away from thehammers. The second micis mired in to preference, ifat all. Realize that the useof the second mic alsobrings phase cancellation.

sound of a piano with the natural rever-berance of the hall (sometimes de-scribed as being "airy"). However, thislistening position also is very muted onthe sound of the hammer striking thestrings (which creates much of the tran-sient of the note). The piano playersposition has much stronger transientsdue to the players proximity to the

Figure 2. Duct tape acrossthe two struts with the miclaying on top of the tape,in the middle

hammers; while the third position hasless transients but a more full bodiedsound due to the more direct reflec-tions off the piano lid.

The ability of the lid to be closed,open on a short stick, or open on a longstick confuses the issue even more.(One act I work with even carries herown mid -size stick). My ideal positionis with the top open (long stick) sittingwith the piano player on the bench, butthat's just my opinion.

The invention of the piano top was agreat volume control from the dayswhen changing acoustics was the onlyvolume control. For quiet work, onewould just close the lid, providing atleast 10 db of attention (volume drop)and a significant muting of the tran-sients. Opening the top allows thevolume and transients their greatestability to fill the music halls of the day,while providing an increase in the deepbass. Of course, the short stick is a com-promise between the two.

The problem in modern times is thateveryone in the music halls want tohear the piano just like it was in hisliving room. This has necessitated theuse of sound systems to augment itsvolume. Of course, the first problem isdeciding which piano sound you wouldlike to present to the public; and sec-ondly, how do you deal with the prob-lem of leakage from other instruments.

Because of my position in sound rein-forcement, I have had the opportunityto see a wide variety of techniques usedto achieve the various desired results.In this article I will present about adozen different ways to mic a piano.However, it should be realized thesound of one type of mic'ing can be al-tered to sound closer to another type ofmic'ing through the use of the tonecontrols, especially the treble control.

HOT SPOTSMy personal preference is the result

of being taken for a "drive" around thepiano soundboard many years ago.With the piano top off, Neil Shurmur,Sammy Davis Jr.'s soundman showedme a number of hot spots on the piano.

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an>-z._.cococo

coc.71

The loudest and fullest sound on thesoundboard seemed to come about 6inches down from the hammers, alongthe long strut in the piano frame. Actu-ally, the loudest point in this hot spotwas about 2 inches away from the struttowards the middle of the keyboard.

Because of this "discovery" I elect tomic the piano with one or two Lavaliertype omni directional microphones.(Figure 1) Now, I already know that halfthe soundmen reading this article aresaying a million statements about mysanity right now, but think of the fol-lowing reasoning: First, an omni-directional mic, dollar for dollar tendsto be flatter in response than adirectional mic. Secondly, if you placedirectional microphone in the piano atthis spot, even with the piano lid wideopen, there still is a reflective surfacewithin about 5 inches of the back of themic (seriously damaging both its rejec-tion pattern and frequency response).Third, psycho -acoustically, what youdon't see, you don't pay as much atten-tion to.

I mic the piano with one lavaliertaped to the main strut, 6 inches awayfrom the hammers. I placed the micwith the element on the inside wall ofthe strut, hanging there off its wire,with the wire taped coming down thestrut to the foot of the instrument. Thecartridge to the mic is left in the body ofthe piano, while the mic wire is then ledaround to the back of the instrumentand draped down the leg. The audiencedoes NOTsee a jungle of metal aroundthe piano, but rather, the instrument inits elegant natural state.

The second mic, if used, is a lavaliertaped to the inside of the short strut atthe 6 inches from the hammer position.The point of this mic is mostly as aspare, but is sometimes handy when apiano is a "dog" with poor high end.

When utilizing the lavalier mic'ingtechnique, I usually end up addingsome highs on the channel EQ for themain mic, and turning down some ofthe lows. This piano technique hasbeen used in all kinds of situat ions fromclassical to rock. In fact, one wellknown pianist bought the mics fromme on the spot. But, it's not the mics asmuch as it is the position.

Despite all efforts to reduce leakageinto the piano, I've found that the bestresults come from positioning the loudinstruments away from the piano. It be-comes very rough to mix when you haveto balance the rest of your mix againstthe leakage into the piano. Despite

Figure 3. A mic placed atthe foot of the piano forthe low end, and one posi-tioned in the center of thestruts for mid range. Thisis also a preferred mic'ingtechnique used by manysound miters.

many claims of various techniques forreducing the leakage, the problem stilloccurs because all sound is able to res-onate through the soundboard. It cannot differentiate between soundgenerated by the string or by a rockband. Piano pick-ups that take sound

Figure 4. Three micro-phones, one at the foot(bass), one in the mid-range section, and one forthe high end. This configu-ration guarantees that allpossible sounds of thepiano are brought forthinto the mix.

off of the soundboard obviously mustdeal with the realities of this situation,but, in addition, lose the sound of thetransients (hammer strike) due to thenature of their use.

Of course, another method of mic'ingis to place one or two mics on stands infront of the piano. Advantages can bethe directional nature of the mic, and

Figure 5. Placing a mic ina hole near the curve ofthe piano emphasizes thepiano sound in the midrange and reduces theamount of the hammertransients. This techniquerequires some judicioususe of eq. , and can behelped by another micover the hammers.

its ability to be placed the 2 inches awayfrom the main strut. However, I feelthat the disadvantages outweigh theadvantages for the reasons previouslystated.

I have seen some people take a largepiece of duct tape and stretch it across

the two struts, and then rest a mic in themiddle of the duct tape (Figure 2). Thepoint of this is to get the sound from themiddle of the piano, while obtainingthe un-mic'd "look."The third figure shows another popu-

lar mic'ing technique, the use of onemic to catch all if the string action,while a second mic is placed over the

middle of the vibrating bass strings.The point of the first mic is similar tothe procedure in Figure 2, however thepurpose of the bass string mic is to re-ceive the sound at the point in thestring that is loudest. Avibrating stringis loudest in the middle, and this resultsin some people mic'ing the bass stringsaccording to their vibration instead oftheir interaction with the soundboard.

A variation on this technique is utiliz-ing three mics on the piano, the firsttwo mics as above, with an additionalmic for the high strings (Figure 4).

One useful parameter in two or moremics on the piano is the ability tochange the PHASE of one of the mics.This change causes the midrange to be-come more prominent or reduced. Ofcourse the use of more than one mic onanything causes phase related cancella-tion, which is why my preference is forone mic properly placed on the instru-ment.

Placing the mic in one of the holes inthe curve of the body (sometimes calledthe "sound holes") is a fairly commontechnique for people who prefer amore "airy" sound. Whether this mic islaid into the piano or placed on a stand,the sound strived for is usually one of

reduced transients and a more "full-bodied" sound.

MORE OPTIONSIn using non -technical terms through

the years, I've discovered that certainwords have meanings that are as-sociated with certain phenomenon.For instance, "bright" means treble, so"dark" means bass; "warm" usually re-fers to midrange, while "full body"means an emphasis on bass and mi-drange over the treble. Of course,adding a mic over the strings to the micin the hole allows you to adjust theamount of transients from the ham-mers to your "airy" sound.

I have also seen these other tech-niques: a mic placed outside of thepiano at the curve halfway in height be-tween the strings and the lid, and also amic placed at the foot of the piano (out-side) so that the mic picked up what theconductor hears. Neither have a lot ofrelevance to sound work.

Another legitimate mic'ing tech-nique is placing PZM type mics tapedto the piano lid in the positions of Fig-ure 1 and Figure 3. This produces whatmany people feel is a very acceptablepiano sound, however just as many

people don't like the sound of thesetypes of transducers. A recent showwith the Modern Jazz Quartet pro-vided a different viewpoint; they likethe positioning of the PZM users butnot the sound, so they wanted standardmics placed in the PZM positions, withthe head of the mic facing the lid so itcaptured the reflective sound of thepiano lid while rejecting the directsound.

I have also in the past seen somepeople take the piano with a mic under-neath to capture just the sound fromthe soundboard, or in various othercombinations. Although I do not pre-scribe to this theory for grand -type pia-nos, it can be very useful when dealingwith uprights.

The point of presenting all of theseideas is to give you more options. Takea tour of the piano yourself, experi-ment, be creative & don't make it feed-back! Remember, experiment on yourown time, don't make your audienceexperiment with you. Make sure youtake advantage of the EQ on yourboard channels to change what you'vegot. After all, nothing is ever perfect, somaybe you'll discover something bet-ter-just don't be afraid to try.

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A Minimalisdc Philosophy

Rather frequently I am askedfor advice on the subject ofsound recording, perhapsbecause I was the first kidon my block to own a re-

cording studio. Many of these seekersare novice recordists who are settingup their own studios or struggling toget "that big sound" from their smallrigs. Having been in this business forabout ten years, I have developed aframework for approaching this mys-tical art/craft/science that I willinglyshare.

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"Minimalism" is the term that I havechosen to describe this methodology.According to Webster's, a minimalist isone who "advocates a program...of aminimal or conservative kind." It isakin to frugality, when frugality is de-fined as efficiency or not being waste-ful, versus "cheap." (But, since theculinary world already has a FrugalGourmet, I have chosen to be a mini-malist. It will be less confusing.)

A LOGICAL APPROACH

The minimalist approach seems par-ticularly logical for those of us practic-ing our craft at some level lower thanthe state-of-the-art. Beginners will fmdthis paradigm invaluable. Further,minimalism is a philosophy that maybeapplied to many aspects of the record-ing field: equipment selection and pur-chase, production, engineering, andmixing, to name a few. Let us examineeach of these areas in turn, from theperspective of the minimalist.

The rationale which we have long ap-plied to equipment acquisition in ouroperation has been to purchase itemswhich are of the required fidelity, re-gardless of other considerations. Im-plicit in this deceptively simple maximare several things. Buy those pieces ofequipment which are of professionalquality, versus professional brand. Ifthe required performance is availableunder a private label brand or througha consumer electronics store-buy it.

We have found, for example, somevery good values at places like RadioShack. Outlets such as this oftenmarket products which are producedfor them by major manufacturers suchas Koss, Sony, Crown, Fostex, Shureand others. This had led us to selectheadphones, microphones, pre -ampli-fiers, meters, monitor speakers andother items from these sources. Ulti-mately one pays a lower price becausethe brand name is not a conspicuous

feature on the equipment, but the qu-ality is still very high.

USING WHAT IS NEEDED

In our operation, we are also cautiousof buying equipment that is actuallyhigher in quality than we require. Thisalmost blasphemous notion recog-nizes that we are, after all, a narrowgauge eight -track studio. Much of ourproduct will be heard over the limitedbandwidth medium of radio, or be re-duced to an audio cassette for playbackon consumer systems, while keepingfuture growth and expansion in mind.

Minimalism in engineering may takeseveral forms. In laying tracks, resistthe temptation to use more micro-phones than really are needed. I havenoted on several occasions thatneophyte engineers will instinctivelyregard the drum kit as an instrumentrequiring at least one microphone perstriking surface-large kits demandingup to a dozen mics.

Experience has shown that is not nec-essarily the case. A simple set up plac-ing microphones on the kick, snare andtwo overhead will often produce excel-lent results. Listen. Let your ears de-cide if that is really all that is required.Until one has a solid understanding ofplacement and phasing considerations,the caveat "less is best" should be keptin mind. After the basics are masteredshould come the expansion and experi-mentation.

Minimalism should always prevail inequalization and the use of effects.

Just be sure that the frequencieswhich you will want to bring out of EQin the mixing can replace what is notthere. But, essentially, it is my beliefthat the emphasizing, boosting andcutting should go on in the mixdown.Good basic tracks will contain a fullrange of frequencies with which towork.


Of course, the "rule" stated above,like all others, is made to be broken.There are certainly times when severeequalization is required in the tracks toachieve the desired end result. Overall,though, try to capture the entire spec-trum initially, alter it later.

Generally, effects should not call at-tention to themselves. Another com-mon tendency for those new toengineering is to overuse certain ef-fects, notably the application of rever-beration. That is particularly true forvocals. Reverberation should only beused to add a sonic environment to thevoice, a sense of the space in which theperformance took place.

Begin with no effect on the signal,then very gradually bring it up in themix, Stop when the vocal exhibits thedesired ambience, before you can"hear" the reverb. Again, experimenta-tion is the only teacher. and, as pre-viously stated, this is obviously anotherrule made to be broken, but is a greathelp in learning to use effects.

Inasmuch as minimalism is theachieving of maximum results withminimum resources, studios withlimited track capability will alwaysbenefit from this philosophy. Takingfull advantage of the narrow gaugestudio may require "pre -mixing" drumtracks, background vocal tracks,rhythm tracks or others.A stereo drum mix can be created

during the track laying and save manyprecious tracks. We generally place thedrum mix on two tracks of the multi-track with the conventional stereoplacement, snare and kick in the centerand toms and cymbals panned acrossthe stereo field.

Limited numbers of outboard devicesmay also necessitate recording of ef-fects during the track laying, ratherthan during the mix. While this com-mitment to a given type and amount ofeffect will make many engineers un-comfortable, it will allow the minimal-ist engineer to take fullest advantage ofthe multi -effect units now popular.

Our practice is to put effects on thedrum tracks as they are laid. Similarly,we will often do the same for guitar andbackground vocal tracks. This allowsus to "save" the effect units for useduring the mix for lead vocals, lead gui-tar, horns or other predominant tracks.

DON'T OVERMIXFinally, minimalism in producing will

demand a layered but unclutteredsonic environment created through the

recording process. Again, many nov-ices will exhibit a tendency to "over -mix" tracks by adding too many parts tothe piece.

As the mix is built, resist the tempta-tion to bring in all the parts simul-taneously. Often a more powerful cutemerges through the interplay of thebasic rhythm tracks, rather thanthrough the addition of many guitarparts, horn sections, or layers and lay-ers of vocals. Bring parts up in the mixselectively.

As the instruments are juxtaposed inthe sonic space of the stereo field, soshould they be juxtaposed in frequencycontent. that is, a mix is structured in atleast three domains: where the instru-ment is placed "left to right" (achievedthrough panning), where the instru-ment is placed "near to far" (achievedthrough level control), and where theinstrument is placed in terms of "har-monic content."

This third element of the sonic spaceis accomplished through the layeringof frequencies. an instrument whoseharmonic content is lower frequenciesis placed at the "bottom" of the mix.Usually that is the kick drum or bassguitar. The next instrument introducedinto the mix should be one whose har-monic content is the next highest. If thelowest frequencies in the mixing arecontained in the bass guitar or synthtrack, the next track should then be thekick drum, whose frequencies areslightly higher.

So, the mix is constructed of layers offrequencies, layers of levels and spatialpositioning or panning. This will pre-vent signals from getting cluttered orlost in the mix because their levels,frequencies or position are to close to-gether.

Keep in mind that what I've termedthe minimalistic is approach is onlyone among the myriad philosophieswhich can be applied to the field ofaudio recording. Its particular useful-ness is for those who have limitedbudgets, limited facilities or those whoare beginning their careers as recor-dists. It would certainly appear to bejust as applicable to many other practi-tioners. And, as stated above, minimal-ism has no "rules;" it is a framework forproblem solving.

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Handbook of

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by John Eargle

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Since this room does not exhibit uniform distribution of absorption,it would appear to be good candidate for the Fitzroy reverberationtime equation. We will calculate the reverberation time using tnatequation,

RT4416(1680) [2 x 20 it 12 2 x 12 x 7 2 x 20 7

(928M - In - In (1,52) - In (I - .04)

RI"269

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480 168 280[

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RT.. - .0003 (8171) 2.4 seconds

The Fitzroy equation gives a value of reverberation time aboutthree times that of the Norris-Eyring equation and is probably a moreaccurate estimate of what will actually take plan in the mom. Nomthat this mom has a pair of opposite walla whose absorption mein.cient is considerably lower than the others in the room. The implica-tion here is that sound will reverberate between these surfaces forsome time after it has died down in other directions in the room. Werecognize this in any rooms as a flutter echo' between parxrelreflective surfaces. and the Fitzroy equation takes such conditionsinto considertion

in in beration time from roanto have longer reverberation titresleech communication are genera lynation time than those used Icor

a of reverberation time as a fur c-arpories are given in Figure 2.19.

"II DISTANCE INDOORS

r in reverberant room, we w IIin Figure 2.20. There is a regii n,wed by a transition into a resit ne reverberant level is in fact

good diffusion and if the eve --ma dun about 0.2 The di. eeverberant fields are eqit this distance the direweed in dB.

Contents

tit cif LEVEL SOUND REPRODUCTION

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In some large spaces. echoes. or discrete reflections. are often aproblem, and they should he eliminated through proper surface treat.merit In motion picture theaters floorio-ceiltng doublefold velourdrapes are quite often used on side and back walls to render the spacequite dead and free of reflections. A sense of ambience in the motionpicture theater is generally created through the surround loudspeakersystem rather than through natural reverberation in the theater.

The motion picture screen itself is quite reflective at high frequencies.

nanyreflectinn off the hack wall is aPt to result in frontleeback

illrf echo in the rantProblems in rortiriling wiolio control rmons are usually more complex

in nature and ore (tn lhow nentislicinna who specialize in them.

NO,LPp.nonn 1 Ma 2 me ire. en on WO .c«. PPS *PO newt. oapanse Mtn. P WanPon en neweven. pap, 41 apl Pow le Pte nom inns nn, Pne 5.PO. type,n pan IP. techn .ye tan m.am a bar. nahliann PO. Man 05

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Sound Reinforcement inCentral America and theCaribbean

his issue is devoted to theSound ReinforcementScene: theory, layout andconstruction. Fledgling en-gineers will find these top-

ics addressed in my articles: I'vealways tried to let my readers knowthe theory and logic behind my audiodecisions. I've faced a lot of problemsin my 15 years of independent en-gineering, and my experience is al-ways taxed by the problems Iencounter overseas. Read on: the so-lutions to overseas problems work athome, too! I'll be writing about NorthAfrica and Micronesia in upcomingissues.

In Los Angeles during the late 1950s,a struggling saxophonist named Or-nette Coleman was introduced to anineteen -year -old trumpeter namedDon Cherry. The two men hit it off, andin 1959 they recorded an album, Some-thing Else, for the Contemporary label.The rest is history: jazz history. This re-cord was seminal in the "free jazz"movement of the 60s; Don Cherry be-came a major voice in this new style.Throughout the 60s, Don worked withSonny Rollins, John Coltrane, AlbertAyler, and Steve Lacy in addition to thetrailblazing Ornette Coleman Quartet.He continued to expand his horizons

Author's Note:I hope that my faithful readers will

enjoy this, my first internationalsound reinforcement article sub-mitted to db in 1989. You may noticean overlap this month: I previouslywrote about Central America in theJuly/August 1988 issue. My mainreason for writing these articles is toprovide my peers with informationon acoustics, electricity, and equip-ment available in each region shouldthey follow in my footsteps; I surecould have used such a referencewhen I started. We played venues onthis tour of Central America that Ididn't visit with Wayne Ibups; hence,I included them in my article.

throughout the 70s, touring the worldand incorporating the music and in-strumentation of many cultures intohis musical identity. Don described his80s music as "world folk music in jazzforms," eschewing the "avant-garde"label often hung on him.

A NEW TOUR

Avid readers of db will recall thatUSIA (United States InformationAgency) contacted me regarding Don'sproposed tour while I was in SoutheastAsia working with Benny Golson (seedb, January/February 1989). I'd alwaysenjoyed Don's music, and had pre-viously worked with him on several oc-casions, so my immediate acceptanceof this tour surprised no one! I was par-ticularly intrigued by Don's currentband. The group, a quartet, would con-sist of reed man Carlos Ward, BobStewart, tuba, Ed Blackwell, drums,and Don on pocket trumpet, key-boards, and doussin' gouni (Malinese"hunter guitar"). What, no bass orpiano? This instrumentation was un-usual for a jazz group, yet in a way verytraditional: early New Orleans jazzgroups were brass oriented, and usedtuba instead of bass for the low founda-tion. I relished the challenge this groupwould present to a sound engineer.Our tour would take place betweenNovember 21 and December 20, 1987,a perfect time to escape my Michiganhome for a warmer climate. Our itiner-ary included Nicaragua, El Salvador,Jamaica, Ilinidad, the Dominican Re-public, and Barbados.

When I returned to the U.S. in earlyOctober, I contacted Sandra Murphy,the USIA program officer handlingDon's tour. My major concern, as al-ways, was to ensure that quality soundequipment could be provided for ouruse. When I first began internationaltouring in the late 70s, "state-of-the-art" sound systems overseas were theexception, not the rule. This situationchanged during the 1980s. While therewere still parts of the world I wouldn'ttour without sound, it is possible to findenough quality equipment in most

ED LEARNED

places to handle an acoustic jazz groupsuch as the Don Cherry Quartet. Myprevious experience in the region ledme to conclude that it would bepossible to pick up sound locally. Theone exception was Nicaragua. My tourof the country with Wayne ibups inearly 1987 (see db, July/August 1988)illustrated the problems of procuringadequate PA equipment, and US IS -Ni-caragua had reported no improvementin this situation. After talking thingsover with Don, Sandra and I decided tobring a small system to Nicaragua.When we left the country, this systemwould be returned to Washington; Iwould then rely on locally contractedsound for the duration of the tour.

USIA owned a complete sound sys-tem, using Bose 800 series PA speakers,Peavey monitors, and Crest amplifiers.The system was stored in Paris and usedprimarily for tours of Africa. With thescope of PA operations continually in-creasing, USIA found the need formore equipment, and purchasedanother complete system in the sum-mer of 1987. This system was also slatedfor Paris storage, but prior to shipmentSandra snagged it and arranged for itstransfer to Nicaragua, where we wouldmake use of it. The new system wasbased on Bose 802 and 302 speakers,JBL monitors, and QSC amplifiers. ASoundcraft 200B console providedmixing, with Yamaha, dbx, and Shurecomponents rounding out the houseelectronics complement. Peavey elec-tric instrument amplifiers and aYamaha PF-85 keyboard were in-cluded for band amplification. Don re-quired a keyboard, so we arranged for itto accompany us on the entire tour.Bob Stewart required an amplifier forhis tuba, but we decided to pick that uplocally, along with the PA equipment,once we left Nicaragua. Microphoneswere another area of concern to me.lbp quality mics are rare in some un-derdeveloped countries, and even theShure SM-58 and SM-57 mics includedwith the USIA sound system are notnoted for their sonic accuracy or mic-to-mic consistency. Maintaining con-sistency in group sound is of

Figure I. Preparing for a sound check at the Edgar Munguia Theater

paramount importance when touringanywhere, but especially overseas,where everything else changes radi-cally! I wanted to ensure that my instru-mental sounds would be consistent, soI arranged to carry my own micro-phones.

PLANNING AHFAD

With Nicaraguan concert planningcomplete, I turned my attentiontoward the rest of the schedule. I

drafted a sound reinforcement andequipment rider outlining our needs.This covered front -of -house consoleand electronics, house and stage moni-tor speaker requirements, stage layoutconfiguration, and stage needs such asa bass amp for Bob, a drum rig for EdBlackwell, and music stands for eachband member. I again used a watts -per -audience -capacity formula when de-scribing PA system power parameters;I'd found this helped local organizersunderstand the need to provide largersystems for larger venues. I did notwant to be underpowered. Sandra sentthis off via cable to each USIS office wewould visit post -Nicaragua. Responsewas excellent in most cases, so we had apretty good idea of what to expect ineach country before we left the U.S. Iwas pleased to discover that I would nothave to worry about converting volt-age: most of our destinations used aU.S. standard 120/240 volt electricalsystem.

I left for New York on November 20to rendezvous with the group for ourpre -tour briefing. Don had returnedthat afternoon from a European tour;

in deference to his jet lag, USIA agencyescort lbney Seabolt quickly con-ducted all necessary group business.After the short meeting, most of usstayed to discuss the environmental,cultural, and political climate of eachcountry we would visit. We also dis-cussed, with Francis Blackwell, Ed'sspecial medical needs. Ed suffers fromkidney failure, and requires peritonealdialysis: simply put, he carries with himdifferent bags of chemicals and,through tubes implanted in his body,gives himself his own dialysis. Withoutthe need for hospital stays or dialysismachines, Ed is able to travel and per-form. However, fluid changes must bemade within a specific timetable, so wemodified ground transportation,sound checks, and concert scheduleswith this in mind. We planned to carryabout a hundred pounds of medicalequipment and chemicals with us,about a ten-day supply; extra supplieswould be shipped ahead to local U.S.embassies and "stockpiled" for us. Ourschedule had been carefully crafted toallow this. I agreed to supervise thetransportation of medical supplies andmusical instruments we'd be carrying;this would be sent together as excessbaggage. Experience dictated this ap-proach: it is the best way to ensure thatgroup equipment travels on the sameflight with the group. It also allows per-sonal attention during customs clear-ance, where delays could be costly to atight schedule.

Our tour began on Saturday, Novem-ber 21, as we all struggled to be at NewYork's LaGuardia Airport by 6:30am.

Our Eastern flight took us to Miami,where we had a three-hour layoverbefore connecting to a TACA flightbound for Managua, Nicaragua. Wehad tagged the baggage all the waythrough to Managua, but I remem-bered my previous experience transfer-ring stuff to TACA in Miami; I toldlbney to hold no truths self-evident.He'd reached the same conclusion, andrelentlessly pursued TACA officials toensure proper transfer of our bags. Iwas ushered into the baggage holdingarea to identify our stuff and confirmthe transfer. This might seem exces-sive, but it was the only way toguarantee that our stuff would makethe same flight. We were delayed anhour leaving Miami, and spent an addi-tional hour on the ground in El Sal-vador waiting for a connecting aircraft,so we didn't arrive in Managua untiljust after 8pm. We were met by two fa-miliar faces: CAS (Cultural AffairsSpecialist) Pauline Frixione and CAO(Cultural Affairs Officer) LoisMervyn. In deference to our tired musi-cians, Thney sent the group off to thehotel with Lois. The rest of us stayed tocollect the baggage and handle cus-toms clearance.

Many changes had occurred since mylast trip to Nicaragua only five monthsago. Everyone was now required to ex-change U.S. $60.00 into cordobas(local currency), prior to customsclearance, at the official (read: finan-cially unfriendly) exchange rate. 'Ilvothings were apparent: design of the cur-rency had changed, and inflation waseven worse. My friend from the Minis-try of Culture, Jose Benito, was notthere to greet us; a new representativereplaced him. I inquired discreetly as tohis whereabouts, and was informedthat he "was no longer employed."Things do change fast in the Ni-caraguan government. Political ten-sions in the region had relaxedconsiderably, as evidenced by the waywe rapidly cleared customs with only aperfunctory inspection of our docu-ments and no search. Pauline broughtme up-to-date on the latest happeningssince my last visit, which included thearrival of Lois: she had been CAO inHonduras a few months before, andhad recently been re -assigned toManagua. Once reunited at the hotel,we held a short briefing so Lois andPauline could acquaint us with ourlocal schedule. We were then free tounwind after our first long travel day-it wouldn't be the last.

Ed Blackwell

Bob Stewart

VOCALANNOUNCEEV ND -757

Don Cherry

POCKET TRUMPET

EV-RE-20

MON

MIX #1

Figure 2. Floor plan and mic layout of the group.

A FAMILIAR EXTERIOR

Sunday was our first performance,and I was eager to get an early start.Pauline had the agency sound geardelivered to the theater in the morning,and I arrived there around 3 pm, a good2 hours before the group. Located inthe heart of Managua, the NationalTheater looked very much like theKennedy Center in Washington, andfor good reason: they were designed bythe same architect. The interior wasdivided into several venues of differingsizes; we would perform in the 300 -seatEdgar Munguia ExperimentalTheater. This theater was a squareroom, with bleachers on three sides forseating. The open side had a curtain,wing space, and ceiling bars with lightsbut no stage; we would set up on thefloor and play to the bleachers. Theacoustics were quite nice: the room wassurprisingly dead, with a reverb time ofaround 1 second, and had a very evenresponse. Power was available fromU.S.-type grounded receptacles on the

rn rear wall and in both dressing rooms. Ig3) measured the voltage at between 128-,- 130 volts, and noticed the dressinga room receptacles were wired out -of-< phase with the "stage" receptacles.

E-2

m The hardest part of setting up the2 sound system was figuring out whatv_a case everything was in. In deference to

the small room, I elected to go withoutthe Bose sub -woofers; I ended up using

ilH

OH

DRUMS

KICK-SENN 421

GNAREWhatever isevadable

locally

DUSSIN'S GOUNI

EV ND -757

Carlos Ward

FLUTE ALTO SAX

EV ND -727 t EV ND -757

MON

MIX #1

only one 802 cabinet per side, elevatedon a tripod stand (Figure 1). I had justbegun to EQ the system when the bandarrived for a rehearsal/sound check. Icould now establish microphone pref-erence for each musician, and get a gripon mixing this unique group (Figure 2).

Don Cherry's major instrument washis pocket trumpet, which he wouldplay both with and without a mute. Hissound had a wonderful quality ofwarmth, so I elected to use my E -V RE -20, a large -diaphragm dynamic that re-ally lent itself to capturing this type ofsound. Its major drawback was largesize and weight. Don preferred to playfacing down slightly instead of facingout at the audience so I didn't need toworry about potential boom stand sag;I could use this mic on an un-extendedstraight mic stand. For announcementsand Don's occasional vocalizing, I usedan E -V ND -757 with a foam blast filter.This mic gave me the reach to pick upDon's voice even if he strayed off-micslightly, something he would occasion-ally do. The doussin' gouni posed themost difficult mic'ing problem. It putout and amazing amount of low end;there were also specific overtones topick up, and the metal scroll on top ofthe neck would rattle sympatheticallywith certain notes. Don mic'd the dous-sin' gouni from a hole in the side; aftertrying several different mics, we settledon a ND -757 with a slightly thinner

blast filter. I engaged the mic's low fil-ter to smooth out the low end, andfound that by leaving the trumpet michot I could pick up enough of the scrollrattle to be appropriate. In the schemeof our performances, Don played thedoussin' gouni solo with vocal accom-paniment, so I didn't have to worryabout bleed from other instruments.Don also played some piano during theshow, using the Yamaha keyboard wecarried with us. The PF-85 keyboardhad an amplifier and two smallspeakers built in; it put out just enoughlevel to be adequate for Don's needs. Iused a direct box to pick the keyboardsignal off the line output.

I'd previously worked with twogroups that featured Carlos Ward: B.T.Express, a pop/funk group with a con-temporary sound, and AbdullahIbrahim's big band, which featured or-chestrated jazz. This small sampling il-lustrated the wide range of Carlos'musical vocabulary. His talents as acomposer were also prodigious:several of his compositions were per-formed nightly by the quartet. On thistour, Carlos played alto saxophone andflute; I gave him a separate mic foreach. This made switching between in-struments much faster, and allowed meto EQ mica differently for each instru-ment. I used ND -757 mks with blast fil-ters for both; Carlos usually asked meto roll off some of the high frequencies

on his alto sax. The flute mic was basi-cally run flat, with just a bit of the lowspulled out to reduce breath noise.Boom mic stands were preferred forboth, although a gooseneck was ac-ceptable for the sax if our stand com-plement was limited.

TUBA IN JAZZ

Bass plays an important role in music:low notes contain the power to supporta composition, and, in the jazz idiom,they can add unique rhythmic, har-monic, and melodic implications. Im-agine the challenge of playing this styleon a tuba: a continuous flow of basssounds must be maintained in supportof the melody and solos, and it must bedone for an entire concert. The instru-ment is physically demanding to play,yet breathing must not interrupt therhythm of a composition.

This was the challenge faced by BobStewart every night. A man of tre-mendous physical stamina, he was putto the test by this task. Bob believedthat the "demise" of the tuba as a majorcomponent in modern rhythm sectionscame about as a result of increasing thevolume of music. As amps and other in-struments created more level, the tu-bist was also required to play louder.The instrument was already so physi-cally demanding that the ante could nolonger be raised; amplified basses be-came the answer. Bob's simple solu-tion: become amplified himself! Heused an Audio-Thchnica ATM -21 dy-namic mic, which he suspended in thebell of his tuba via rubber straps. Thismic was run into his direct box throughthe use of a low Z -high Z line trans-former. At that point, the signal wassplit to feed Bob's amp and the PA sys-tem. Bob preferred an electric bassamp; we discovered the hard way thatmost guitar amps couldn't handle thelarge transients that Bob was capableof delivering. With a little EQ, he couldget that amplified tuba plenty loudwithout stage feedback. Withouthaving to waste energy attainingvolume, Bob could conserve hisstrength for playing music. The sound Igot was excellent; Bob usually wantedme to reduce the highs just a touch, andin some places we might reduce lowend just enough to prevent the soundfrom becoming too boomy.

Ed Blackwell has the respect ofdrum-mers everywhere; his approach to per-cussion has been called the "mostadvanced in jazz to date." I'd firstworked with Ed during his tenure with

Figure 3. Neysy Rios Auditorium, Central American University. Lois and Tongroll out the drum rug.

Old and New Dreams, where he madean indelible impression on me. Ed'sencyclopedia knowledge of rhythmsand sense of colors struck me as salientpoints in his approach. I wanted thebalance between drums to be dictatedby Ed, not me, so I decided to use mini-mal drum mic'ing. Ed played Sonordrums, with the kit based around an 18 -inch bass drum, 1414 -inch metal snare,9x13 -inch mounted tom, and a 14 -inchfloor tom. His cymbals were all Paiste,and included 14 -inch hi -hats, 22 -inchride, 18 -inch crash, and an 18 -inchChina -type. Our concerts in Nicaraguawere held in such small venues that I

never needed to mic the drums; I wouldlet Ed play and balance the band tohim. For larger venues, I mic'd the bassdrum with my Sennheiser 421. For therest of the set, I used the best mics wecould procure locally. I would roundout drum mic'ing with a snare mic andtwo overheads at larger venues, butmost often went with just kick -over-head.

PERSONAL MONITORING

Monitor placement for our group wasobvious: each musician had his ownwedge. The actual distribution ofmonitor mixes, however, sorted itself

Figure 4. Ed Blackwell prepares for the second Managua concert.

Ui

CDnt

out during our first soundcheck. Donand Carlos wanted to hear themselveson top with just a taste of Bob. Withcareful placement, I could not onlycover them with the front two wedges,but get enough horns in the back tosatisfy Bob and Ed, too. As a result, allBob needed was tuba. This necessi-tated a separate mix, comprised only oftuba. Bob also wanted me to "crank itup" d uring the last few tunes of any per-formance, when he began to get tired.Ed could hear the horns fine off thefront wedges, and just needed a little ofBob. I ran his wedge off Bob's mix; thatwas good, but a little too loud. I solvedthis discrepancy by turning down theamplifier channel feeding Ed's wedge.If I didn't have the luxury of dedicatedamp channels/wedge, I would simplymove the wedge away from Ed until weachieved the desired drop in level.

What I heard at sound check servednotice that I had a hot band on myhands! Our 7:30pm concert drew anoverflow crowd of 400 that packed theplace, even covering the floor. Thegroup played the room perfectly;acoustic drums and tasteful playingmade good sound a snap. Ed and Bobwere swinging hard, with both Don andCarlos taking off! I was reluctant tomodify this gorgeous sound, but alovely flute solo by Carlos on his ownLeto immediately tempted me to add atasty touch of reverb via a YamahaSPX -90. One doesn't take libertieswith sound, however, so I asked theguys about my effect during intermis-sion. They loved it, and told me to "dowhat's appropriate, subtly." I used thereverb sparingly, and, when Don per-formed his solo "doussin' gouni blues,"I faded in some delay on his voice thatmatched the rhythmic cadence of hissong. He really loved that, and told meafter the show to do it on a regular basis.The audience was dazzled, calling thegroup back for an encore; many stayedto chat after the show. I tore downquickly with the assistance of willingaudience members, and was soon backat the hotel toasting our opening nightwith the guys.

MEDIA PERFORMANCEDon and the group were kept very

busy on Monday with several radio andTV interviews. My workday began alittle later: at 3pm, I took the gear overto the Central American University,where we would perform at the NeysyRios Auditorium. This proved to be alarge lecture hall with the "stage" atone end of a rectangular room; the

sides were louvered and open to the air(Figure 3). All room surfaces were hardand reflective, and the "open air" de-sign did little to offset room reflections:reverb time was around 1-3/4 seconds,and room sound was overly bright. I lo-cated many U.S.-type AC receptacles,but the only ones with functionalgrounds were on the stage right wallfacing. This room was even smallerthan last night's; I again used only 1Bose 802 cabinet/side with no sub -woofers, and let the drums go acoustic(Figure 4). I was forced to roll high -endoff almost everything in an attempt todeal with the room's over -enhance-ment. The monitors were also run sub-stantially hotter as the group struggledwith room reverb. Fortunately, theaudience rescued us-we again had anoverflow crowd, which helped dry upthe room considerably. Capacity waspurportedly 450, yet university officialspegged our primarily student audienceat around 1000. Not only was there notone square inch of room inside, butpeople were lined up three deep out-side, listening and trying to watchthrough the wall louvers. Things weregoing great until the house right PAspeaker cut out halfway through thesecond set. I had to pick my waythrough masses of seated students toreach the power amps, which were hotenough to fry eggs! The system amprack contained 1 QSC 3350 and 2 QSC3500 amplifiers in an Anvil case just bigenough to accommodate the threeamps. With no space in between for airflow and no fans, it was no surprise theamps were going into thermal protec-tion. In short order, the other workingamps shut down as well. While I silentlycursed whoever had designed this rack,I rapidly combined loads and switchedto unused amp sides. I was forced to re-peat this procedure four more times tocomplete the show, as one amp sideoverheated, another would cool offenough to use. In this sweltering room,the amps never stayed cool for long; Iguess the air-conditioned environmentof the National Theater had saved mefrom a similar fate there. I explainedthe problem to lbney and Pauline; theyagreed that the rack should be returnedto Washington for modification. In themeantime, Pauline arranged for me toborrow a small desk fan from her officeto tide me over.

Thesday featured a lunch in our honorat the Casa Grande; this fabuloushome, perched high on a hill overlook-ing Managua, is now used as a guesthouse by the U.S. Embassy. Our per-

formances were the talk of the town:Lois informed us that the embassyphone was ringing off the hook with re-quests for passes or tickets. I returnedto the friendly confines of the EdgarMunguia Experimental Theater laterthat afternoon to prepare for our sec-ond concert there. Nicaragua's RadioSandino planned to broadcast the con-cert live, so I arranged to meet withtheir engineers at the hall. Surprise,surprise! They were the same guys whohad done the Wayne Ibups broadcastwith me. It so happened that we were allwearing our Zydecajun t -shirts, whichled to a lot of good-natured joking! Wedecided to do what had worked so wellduring my last visit: they took theband's audio feed from me, using theirown mics for ambience and radio an-nouncements.Our third consecutive capacity -and -

over crowd was primed for this concert,and, since the guys were already accli-mated to the theater, they were in-spired to new heights. The audiencewas a unique cross-section of society:Sandinista officials, Nicaraguan stu-dents, internationalists, and Ameri-cans all gathered to spur the band onwith raucous applause. Ideological andcultural differences were set aside inthe enjoyment of exceptional music.Don improvised a "Managua blues"during his doussin' gouni solo; Bobshocked the audience with several"elephant cries" on his tuba. Carlosripped off some fiery solos, with plentyof support from Ed's bubbling beat. Ihad my hands full doing two mixessimultaneously: the radio feed wasradically different in balance and con-tent from the live PA mix. I'd mic'd thedrums, but only assigned them to theradio buss. This necessitated morehorn level to keep up; I had to be espe-cially alert during solos to prevent thehorns from dropping out or becomingtoo loud. I monitored the radio feed viaheadphones, removing themfrequently to check the live mix.Frequent changes were essential forgood control. I'd asked I0 (informa-tion officer) Alberto Fernandez to tapethe broadcast on cassette for us, and wewere able to listen back to it that nightafter we returned to the hotel. Don toldme I'd done a good job on the mix, andeveryone agreed that the effects wereappropriate. I was fairly sure I had itdown at this point, but it always helpsthe confidence to hear it from thegroup. EE

At long last, all the questions you everasked all the problems you ever grappledwith are answered clearly and definitively,

Haiku*Handbook

In 256 fact -filled pages, liberally sprinkledwith over 500 Illuminating photographs,drawings and diagrams, John Eargie coversvirtually every practical aspect of micro-phone design and usage.

Completely up to date, this vital new handbook isa must for any professional whose work involvesmicrophones. Here are just a few of the topics thatare thoroughly covered:

Directional characteristics-the basic patterns.Using patterns effectively.Microphone sensitivity ratings.

Remote powering of capacitors.Proximity and distance effects.Multi -microphone interference problems.Stereo microphone techniques.Speech and music reinforcement.Studio microphone techniques.Microphone accessories.

And much, much more!THE MICROPHONE HANDBOOK. You'll findyourself reaching for it every time anew or unusual problem crops up. Orderyour copy now!

JOHN EARGLE,notes author, lecturer and audio expert, is vice-president,market planning for James B. Lansing Sound He has alsoserved as chief engineer with Mercury Records, and is amember of SMPTE, IEEE and AES, for which he served aspresident in 1974-75 Listed in Engineers of Distinction,he has over 30 published articles and record reviews tohis credit, and is the author of another important book,Sound Recording

lheMicrophone

HandbookJohn

,J$31.95

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ELAR PUBLISHING CO INC.203 Commack Road, Suite 101C, Commack, NY 11725

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SOUNDCRAFTSMEN MODEL 300x4 POWER AMPLIFIER

GENERAL INFORMATIONThe Soundcraftsmen 300x4, as its name suggests, is a four -

channel amplifier. No, Soundcraftsmen is not suggesting areturn to so-called "quadraphonic" sound reproduction inprofessional applications. Rather, one of the chief advan-tages of this unusual configuration is its flexibility. It allowsthe user to select either two -channel, three -channel or four -channel operation. It makes an ideal amplifier, for example,for the large recording studio that requires very high powerfor monitoring. Used in the two -channel bridged mode, itwill deliver 600 watts per channel into 8 ohm loads. Alterna-tively, you can bi-amp your monitors (using the amp in itsfour -channel mode) to obtain 210 watts per channel at 8ohms. Still another possibility is tri-amping, using two of theModel 300x4 amps, each in the three -channel mode, to pro-vide 600 watts per channel for the woofers and 210 watts perchannel for the high frequency drivers.

The 300x4 occupies the equivalent of three rack spaces inheight. It has two completely independent power suppliesand two separate power transformers. The 300x4 is

Figure 1. Frequency responseAnplitnAe <dB) versus Frequency (Ns): SounAeraftsmon 399101 An,3.001111

4.OWAN

completely protected against short circuits and input over-loads. Thermal protection is provided by multi -sensor phasecontrol regulation as well as two multi -speed cooling fans.

The basic circuitry of the 300x4 is similar to previous mod-els offered by Soundcraftsmen. The company is convincedthat power MOSI-EA are not only more reliable than otheroutput devices (they are self-limiting as far as dissipation isconcerned) but also provide what some have described as"tube -like" sound quality that many professional soundequipment users consider to be superior to the "transis-torized" sound of bipolar transistors.

In many respects, the circuitry of the 300x4 is almost iden-tical to what you would have if you installed a pair of Sound -craftsmen Model PM860 amplifiers in a single rack -mountpanel (their Model PCX-2 rack -mount front panel), exceptthat the designers of this four-channel/three-channel/two-channel amplifier have beefed up the power supply andtransformer capabilities so that the amplifier can truly beconsidered a low -impedance, high -current, high -wattageunit.

Figure 2. Spectrum analysis of residual noise (1 -wattoutput reference level).1mr1;na Analysts of Airs.Anal Noise (AB) vs. frequency (11:); 361%4 hop iiiii r

7N. NN

flN NN

A

INN I)

-7/.

11

-1

IOC s5Nosse (Z) vs Frequency (Ho) at rated rower, Sound...4(1.1e/, 30994 NOAS. CO vs. Peter Output, Some ***** 300X4 anylsfter

O .1

0.010,

0.001

"ell is lk_ 14k 34I,

Figure 3A. Harmonic distortion plus noise versusfrequency, at rated power (210W/channel, 8 ohm loads).

The amplifier that we tested was, in some ways, a prototype

model with some minor changes in circuit board layout and

wire routing still to be finalized in production. We were as-

sured by Soundcraftsmen, however, that all major com-ponents as well as the high current, low -impedance power

transformers used in our sample are the same as those thatwill be used in final production. Frankly, we don't know why

Soundcraftsmen even bothered to mention the prototypeaspects of the sample; to us, the "innards" of this amplifier

looked a lot better than those of some models presented toTOP 0ftise (x) vs. Frequency IN.) at rated rower; Sousio rr n 3091(4

O .1

lk 114, 24k

Figure 3B. Harmonic distortion plus noise versusfrequency, at rated power (300W/channel, 4 ohm loads).

us as actual "production models."

Figure 3C. Harmonic distortion plus noise versusfrequency, at rated power (600W/channel, 8 ohm loadsbridged mode).TOD .11else (10 vs. Frequency (Nat at power. Sound. rrrrr men 39994

O .1

9.991,

.11191111520

1 I I

190 lk lik

9.1

9.910

9.9954., 10 500

Figure 4A. Harmonic distortion plus noise versus poweroutput per channel (8 -ohm loads). 20 Hz and 1 kHz, lowercurves; 20 kHz, upper curve

FRONT AND REAR PANEL LAYOUT

The only control found on the front panel is the powerswitch. When activated, there is a momentary delay beforefull operation of the amplifier is available. Banks of greenLED indicators (three on each side of the amplifier's frontpanel) tell the user which mode is being used. Two of theLEDs on each side illuminate when the amplifier is operatedin the four -channel mode while the third LED of each bank

Distortion Noisy (V) vs. Feuer Output; Sonnet rrrrr men 39994 horilf.er5

0.1

0.010

0. 0955.21 10 100 11,

Fiigure 4B. Harmonic distortion plus noise versus poweroutput per channel (4 -ohm loads). 20 Hz and 1 kHz, lowercurves; 20 kHz, upper curve.

illuminates when the amplifiers have been switched to thebridged mode. Additional red LEDs ill uminate when ampli-fier clipping or overdriving takes place. Finally, there arealso two circuit -breaker reset buttons that are used to re-store amplifier service in the event that these breakers open

Figure 4C. Harmonic distortion plus noise versus poweroutput per channel (8 -ohm loads, bridged). 20 Hz and 1kHz, lower curves; 20 kHz, upper curve.

SNP/I-IN Di ion (x) vs. Power OD; Sounderaftswen 31111.4

11.11111,

COSI

Figure 5A. SMPTE-IM distortion versus power output,8 -ohm loads.

1. ISO SOS

for whatever reason. During the entire course of our lab test-ing, it was never necessary to use these reset buttons, a factthat attests to the ruggedness and reliability of the amplifi-ers. We probably subjected them to more stress than they arelikely to get under normal operating conditions when fedwith music or speech signals.

The rear panel of the 300x4 is equipped with four sets ofcolor coded five -way speaker binding post terminals. Whenthe amplifiers are bridged (for two channel, stereo opera-tion), connection of load is made from red terminal to redterminal of the same amplifier pair. Otherwise, connectionof loads is made from red to black terminals. Slide switchesare provided for selecting bridged or 4 -channel mode, so thatno internal wiring changes need to be made when going fromone mode of operation to the other.

One surprising aspect of the design was the absence ofbalanced inputs commonly found on amplifiers intended forprofessional use. The only inputs available are unbalancedtype, via 1/4 -inch standard phone plugs. That's certainly astep above those consumer type "phono tip" jacks, but shortof the more rugged 3 -pin XLR connectors which might havebeen used even if only unbalanced inputs were provided.There are no level controls on the rear panel, and input sen-sitivity is therefore fixed at around 1.3 volts for rated output,when in the unbridged, four -channel mode.

LAB MEASUREMENTS

The 300x4 amplifier exhibited flat frequency responsefrom below 10 Hz to 20 kHz, within 0.1 dB. The graph ofFig-ure 1 illustrates that response extended beyond the audiospectrum and was down by only -1.7 dB at 100 kHz. Re -

Figure 5B. SMPTE-IM distortion versus power output,4 -ohm loads.

0.1

0.010.

I 9.901

SOME -IS Distortion (x) vs. Power (14); Sounds, return 301194

10 ION

sponse was virtually identical for all four available channelsor, in stereo bridged mode, for both bridged channels.

Referred to 1 watt output, A -weighted signal-to-noiseratio measured 77 dB. 'franslated to a rated output of 210watts, the S/N ratio would be just over 100 dB. This falls a bitshort of the 105 dB claimed by Soundcraftsmen for the simi-lar PM860 amplifier, whose specifications are supposed tobe similar to those of the 300x4. The reason for this may wellhave to do with the prototype nature of our sample. As canbe seen in Figure 2 (a spectrum analysis of noise versusfrequency of this amplifier), substantial peaks of noise showup at the power -line frequency (60 Hz) and at its third har-monic. No doubt the final wiring layout, of which Sound -craftsmen told us, will bring the S/N ratio to well within therated spec.

Figure 3A shows how total harmonic distortion plus noisevaried as a function of frequency, with input regulated so asto produce rated output (210 watts per channel) into 8 ohmloads. Under these conditions, THD plus noise at 1 kHzmeasured only 0.0072 percent at 1 kHz, virtually the samevalue at 20 Hz and a somewhat higher 0.031 percent at 20kHz. Even at that upper frequency, THD plus noise was farbelow Soundcraftsmen's rated value of 0.05 percent. Thesame sort of measurement was repeated for 4 ohm loads,with input regulated to produce a constant 300 watts of out-put per channel. Results are shown in Figure 3B. At mid andlow frequencies, THD plus noise for these loads remainedextremely low, while at 20 kHz, we measured a THD plusnoise figure of 0.095 percent. Finally, the same measure-ment was repeated for the bridge mode, using 8 ohm loadsand regulating the input so as to produce a constant 600watts per channel. Under these conditions, THD plus noiseremained slightly higher than 0.01 percent at low and midfrequencies, rising slightly to 0.027 percent at 20 kHz, asshown in Figure 3C.

Figures 4A, 4B and 4C present plots of THD plus noise as afunction of power output for the three conditions described.The apparent higher percentages of THD + noise at lowoutput levels are not, in fact, harmonic distortion but rathernoise contributions referred to those lower levels.

Figures 5A, 5B and SC show how SMPTE-IM distortionvaried as a function of power output levels for 8 ohm, 4 ohmand bridged (8 ohm) operation. In this case, the percentagesremained well under 0.05 percent at rated power levels (210watts for the 8 ohm/4 channel mode, 300 watts per channelfor the 4 ohm/4 channel mode and 600 watts per channel forthe bridged, 8 -ohm stereo mode.)

Figure 5C. SMPTE-IM distortion versus power output,8 -ohm loads, bridged.

SMPTI-IM Distortion (.) vs. Power (11); Sounderaftswen 3119(4

0.)

0.010

9.001

'a..511. IS ISO IS 1

Input sensitivity of the amplifier, referred to 1 watt output,measured 87 mV in the bridged mode. Damping factor, re-ferred to 8 ohm loads and using a 50 Hz test signal, measuredin excess of 200. Dynamic headroom, using 8 ohm loads,measured just over 1.0 dB.

COMMENTS

As has been true in tests of other Soundcraftsmen poweramplifiers, their chief attributes have been excellent reliabil-ity and superb sound quality. Many an amplifier that we'vetested over the years sounds good when driven to moderatelevels with music signals but doesn't stand up in the fieldwhere it is often pushed to its limits. Our bench tests prob-ably subjected this Soundcraftsmen amplifier to conditionsthat it is not likely to encounter even in the most demandingsound reinforcement applications. Yet, the amp never fal-tered, never shut down and, amazingly, didn't get all that hoteither.

As for sound quality, we completely agree with Sound -

craftsmen's engineers as far as their choice of MOSFETout-put devices is concerned. For that matter, there are a lot ofamplifiers out there that employ far-out tricks to bringmeasured distortion levels down to "triple zero" numbers ofdistortion following the decimal point, but when you hookthem up to real -world speaker loads their sonic quality fallsshort of matching the bench test numbers. Not so with theSoundcraftsmen 300x4. To be sure, the amplifier's THDfigures are not the lowest on record, but if there is anyone outthere who can tell the difference between 0.05 percent THDand 0.005 percent THD we have yet to encounter such skills!By taking a straightforward approach to amplifier design,Soundcraftsmen has consistently been able to deliver ampli-fiers that perform reliably and arc well suited for the kind ofuse :owhich they are likely to be put in studio monitoringsit-uations as well as in sound reinforcement applications. Bestof all, the 300x4, like other amplifiers from this company, isfairly-make that more than fairly-priced compared withthe competition.

SPECIFICATION

VITAL STATISTICS

MFR'S CLAIM db Measured

Power Output 8-ohm/4 Ch.

4-ohm/4 Ch.

8 -ohm Bridged

Rated THD(8 ohms)

Sensitivity

Damping Factor

Signal -to -Noise

IM Distortion

Dynamic Headroom

Dimensions (WxHxD)

Weight

Price: $1299.00

210 watts/ch

300 watts/ch

600 watts/ch

0.05%

1.2 Volts

More than 200

105 dB

0.05%

N/A

19x5 -1/4x12 inches

58 Lbs.

230 watts/ch

420 watts/ch

720 watts/ch

0.032%Input

1.3 Volts

Confirmed

100 dB (See text)

0.009% (8 ohms)

1.02 dB

Confirmed

Confirmed

JOHN BARILLA

TI r T i iii\II 1, riTTA nri L. I L L. I I \IJI I I /-% L.

Mike Mandel: The Songwriter's Dreammaker

Everyone who would succeed inlife must carve out a niche-a spacewhere one's skills can be seen as uniquein the marketplace. This reality isdoubly true in the highly competitiveworld of the professional musician.Electronic cottage facilities have pro-vided some musicians with a new, andvirtually unlimited arena for theirtalents, where their hard-earnedchops-the product of numerousgrueling years on the road-can beprofitably utilized without ever havingto leave their home. One such musicianis Mike Mandel.

My recent encounter with Mandel'sproduction skills started in the livingroom of a friend. A few weeks earliershe had played me some rough demosfrom a songwriter she knew. The songswere well -crafted but needed some se-rious arrangements and production inorder to be professionally acceptableby today's sophisticated standards. Sheexplained how this songwriter hadstruggled for years to get a publishingdeal, all to no avail until recently, whenon the strength of some new demos hehad paid someone by the name of MikeMandel to produce for him, he hit pay-

dirt. Tbday she wanted me to hear thesenew demos.

PLEASANT SURPRISE

She was excited that her friend had fi-nally signed a publishing deal, but I wascurious as to what kind of productionhad made the difference. By telling meabout a producer from New York Citywho transforms songs into commer-cially viable entities for a very rea-sonable fee, she had piqued myinterest. Cynically, I expected a quick -fix, bang -em -up MIDI production, butwhen I finally heard Mike Mandel'streatment of these songs I was quite im-pressed.

What I heard was something beyondcompetent production. It was subtle,nuanced, the evidence of not only agood programmer, but a master musi-cian and arranger as well. The nameMike Mandel sounded familiar, but Icouldn't place it. So I decided to pay avisit to this songwriter's dreammaker.

Mandel's electronic cottage is locatedon the 20th floor of a beautiful apart-ment complex on Manhattan's westside. Perched high above any neighbor-ing buildings, it offers a clear view outto the Hudson River-a feature which

is undoubtedly inspirational to hisclients. Mike Mandel however, is not atall concerned about the view from hisstudio. His source of inspiration comesfrom other places.

He has been blind since early child-hood.

Arriving at the studio, I was greetedby Mandel and his guide dog, Clyde. Wespent a very pleasant two hours talkingabout production techniques, philoso-phies of music and the special require-ments of outfitting a studio for anunsighted operator. Additionally, Ifound out a little bit more about MikeMandel and why his name had such afamiliar ring.

As it turns out I had seen Mike Man-del before, perhaps several times. Ifound out that he had done a lengthystint with radical jazz guitarist LarryCortyell (and the Eleventh House). Ihad seen the group on several occa-sions, and was extremely impressed bythis blind keyboard virtuoso. By sheerserendipity, it turns out that we lived onthe same street in Boston during theearly seventies, while we both studiedat Berklee College of Music.

Figure 1. Mike Mandel composing at thepiano keyboard.

Evidently, Mandel took his trainingmuch more seriously than I did. AfterBerklee he spent three years at the NewEngland Conservatory, on to the Bos-ton Conservatory, followed by privatestudies with noted arranger, Don Se-besky.

MUSICAL BACKGROUND

In addition to all the academicplaudits, Mandel has been involved in apretty diverse array of musical projects.He has solo albums on the Vanguardlabel, has recorded with artists asdiverse as Deodato and Glen Camp-bell, done scads of commercials forsome rather upscale clients, providedsource music for all your favorite soapoperas, been a product specialist forCasio synthesizers, and toured withrock bassist Jack Bruce and with vocal-ist Roy Orbison.

With that breadth of experienceunder his belt, what could he be up tonext? Mandel feels that the diversity inhis musical background really comestogether best in the context of his elec-tronic cottage. It is here that he puts itall to work, producing songs for otherwriters with the authentic flair of onewho has actually "lived" that musicalstyle.

Since coming off the road, Mandelhas built a thriving business out of hisEC. Perennially servicing severalclients at the same time, his only fear isnot being able to turn around a produc-tion in a timely fashion-somethingwhich only rarely occurs. But even withhis busy schedule Mandel seems un-usually sensitive-almost altruistic-towards his clients' needs. Aware thatstruggling songwriters are not a

Figure 2 Racked keyboards partially ob-scure the high-rise view beyond

wealthy lot, he maintains a very afford-able rate structure, so that writers willbe encouraged to demo their songsseveral times a year. By keeping to a setfee, with no hidden extras, Mandel'sclients know what to expect to pay for afinal product and can more easily pro-ject their long range budget.

COUNSELING THE CLIENT

A big feature of Mandel's service isthe first "sit-down" meeting with theclient-a service for which there isnever any charge. The client will showhim a rough version of the song andMandel will fire up his drum machineand a few synthesizers and give theclient his impression of which direc-tion the song ought to go. This includesexploring rhythms, tempos, soundcolors and textures and that inde-scribable substance called "feel." Thisis all done in real-time, essentially a liveperformance for the client. If the clientis pleased with the direction, then thisinitial meeting ends and Mandelproceeds with the production pri-vately. 11 -eating each song as a uniquepuzzle to be solved, his productionstyle rests on a very mystical founda-tion. Says Mandel:

"I believe in building moods and at-mospheres for a song. Each song, be-sides having a distinct groove, has adistinct mood and atmosphere. I thinkthat's what distinguishes one songfrom another. Not just it's point ofviewabout the lyrics, but the atmosphere itestablishes-the way it touches ahuman being."

Now all alone in his electronic cot-tage, Mandel begins to create those"moods and atmospheres" utilizing

some of the classic tools of the trade.His keyboard array is modest by somestandards, but evidences judiciouscost-effective buying. Essentially, allthe bases are covered.

STEP-BY-STEP

The Yamaha DX7-II, with its distinc-tively clear FM sounds serves also as amaster keyboard for Mandel. The En-soniq ESQ-M adds the uniquestrengths of wavetable synthesis, whilethe Roland D-550 fulfills the need forsampled sounds. Yamaha's TX 81-Zprovides some nice extra FM soundsand flexiblevoice allocat ion all in a box,and the ubiquitous Roland D-50 con-tributes its characteristic breathiness.And since no modern digital gizmo canever replace the nice, fat sounds andreal-time programmability of analogsynthesis, Mandel has wisely included aSequential Circuits Prophet -5 and anOberheim Xpander to his arsenal.

While the production method mightvary for different musical styles, it usu-ally starts with Mandel establishing agroove on his Korg DDD-1 drum ma-chine. (He also uses the Alesis HR -16as a drum expander to add versatility tothe sound.) A bass -line is then estab-lished and recorded into his sequencer,utilizing the rich timbres of theProphet -5 and/or the Xpander assound sources.

Once the groove is happening, Man-del starts fleshing out the sound tex-tures which form the foundation forthe "moods and atmospheres" he isseeking. A typical step in this processwould be to lay down a pad (a diffusewash of sound which will serve as a sortof musical "glue" to hold the produc-

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tion together). Typically for Mandel,this might involve a combination ofsounds-perhaps one of the notableelectric piano sounds from DX7-IIcombined with complementaryethereal sounds from the ESQ-M orthe D-550 -hard panned in oppositedirections.

FROM THE SEQUENCERFrom this basis, various colors,

rhythms and counter -melodies areadded-all stored in the sequencer forlater manipulation. When the produc-tion is ready for vocals, the client, vo-calist and possibly a liveinstrumentalist such as a guitar player,are brought in for a recording session.The night before the session, Mandel,who prefers doing his initial drum pro-gramming directly on the drum ma-chine, executes a MIDI data dump (ofthe compiled drum patterns) into hissoftware sequencer.

The sequencer is then locked to hismulti -track machine (an Otari MX-

50/50 -8 track) by laying down a sync -tone. The sync -tone Mandel uses is notthe standard FSK tape sync which isoutput by all sequencers and drum ma-chines. The standard variety locks upwell enough, but since it contains no lo-cation information (other thanstart/stop), it is not possible to go overa passage of the song without startingall over from the beginning. In recentmonths several companies have begunmanufacturing interface boxes whichdirectly translate the MIDI clock in asequencer into a new variety of FSKwhich contains continuous MIDI songpointer references imbedded in thecode, thereby enabling the user not

only to synchronize to tape, but to startand stop sequences along any point ontape. While SMPTE time code has longoffered the same feature (and manymore as well), this new breed of FSKgenerator/readers does everything asongwriter or music producer couldwant it to do. Mandel uses a box by JLCooper called the PPS, sometimes re-ferred to as "poor man's SMPTE" (itlists for only $199). Mandel has noth-ing but praise for this highly reliableproduct. "If I go video hook-up, I'll goSMPTE. But for this (songwriterdemos), I don't need it. PPS works likea dream."

Following the live session, Mandelwill take a day or so to examine thetracks at his leisure. He may choose toadd sweeteners at this time or perhaps,since all synthesized tracks remain as"virtual" tracks, he may experimentwith various combinations of synthe-sizer patches, changing the programsto provide the best possible comple-ment to the vocals. The sounds and tex-tures remain flexible right up until thefinal mixdown. Only live tracks anddrums are printed to tape. Strictlyspeaking, the drums don't have to beprinted either, but since he likes toprocess each element of the drum kitseparately, it is usually preferable to doso while tracking instead of tying upsignal processors during the mix.

Mandel usually mixes on YamahaNS -10M speakers, but also has a weird -looking custom made pair of speakersfora hypey low-end/zizzy high -end typereference. (They are 5 -way speakerscontaining 12 -inch, 8 -inch and 5 -inchspeakers, plus a tweeter and super -tweeter.) Mandel reserves those

Figure 3. Tape recorders and mixers all ar-ranged as a desk -shelf convenience forMandel

speakers for clients who are dancemusic aficionados and want to hear asound that will, as he puts it, "rattleyour teeth." There are however, limitsto how much teeth rattling can go on inan urban apartment building, so thesespeakers cannot be monitored for ex-tensive periods of time. Finally, as amatter of course, Mandel routinelyprocesses all his mixes through the Bar-cus Berry BBE Maxi, another in theproliferating number of aural exciterson the market. He likes the subtle har-monic transformation that goes onwith the BBE and feels that this giveshis mixes a little extra punch.

THE TALKING COMPUTER

I was interested in finding out how anunsighted person interacted with hiscomputer (and for that matter, how heinteracted with all the audio equip-ment in his studio). I asked Mandel togive me a demo of how his systemworked.

The first obstacle a blind computeroperator faces is learning the software.Software generally comes with aprinted manual-sometimes the sizeof an urban telephone book-to helpyou learn to operate the program.Blind people do not have this option,so they have to be resourceful. Theyhave several options before them: 1)they could pay a sighted person to readthe manual onto a tape for them 2) theycould see if any public or private or-ganization for the blind would have atape of the manual on file for them topurchase, or 3) they could check withthe manufacturer to ascertain if anASCII file of the manual is available.

Figure 4. This specially -designed box per-mits Mandel to hear his audio switching.

For Mandel, the third option is themost preferable. Using a Leading Edgecomputer (IBM compatible) with a 20MEG hard drive, a screen reading pro-gram and speech synthesizer card (withappropriate software to drive it), Man-del is able to "listen" to the ASCII ver-sion of the manual. This same voicecard/screen reader combo enables himto negotiate all the software he needs toproduce music.

As a software sequencer Mandel usesboth Magnetic Music's 'Ibxture 3.1 andVoyetra's Sequencer Plus Mark III. Fortweaking his synthesizer patches, heuses Voyetra's Sideman voice editor forthe TX81-Z, D-50 and DX -7. Voyetrascores heavily with Mandel as he alsoutilizes their Patchmaster voice librar-ian.

I sat back and watched as Mandelpunched up some tracks he had beensequencing using the fixture program.Calling up a page of the program hewanted to work with, he directed thecursor-one increment down at atime-until it rested on the line hewanted to read. It contained someinformation on track assignments, in-strument names, controller informa-tion and some other things I'm notquite sure of. When he instructed it toread, it would read the entire line fromleft to right (unless he instructed it todo otherwise). Faithful servant that itwas, it read everything-not just words,but all alpha numeric info includingpunctuation. Sounding a bit like a na-tive-born Rumanian android, it spitout a phrase that sounded somethinglike, "RIM -SLASH -1A- SLASH -3-DOT-DOT-DOT-3-DASH-1-9-5."

Mandel said it would sound a wholelot more natural if he sped it up andshut-off the punctuation command. Ilistened back, but it was still all Greekto me (or was that Rumanian).Nevertheless, he assured me that onceone got acclimated to the sound andlearned the layout of the program, itwould be easy enough to interact with.Apparently, he has become very profi-cient at using it.

In fact, Mike Mandel interacted morequickly with his computer than asighted person could, because he didnot need to stop and divert his gaze inorder to take in visual informationfrom the screen.

AUDITORY PPMMonitoring recording levels is almost

impossible without proper metering.Thanks to an organization calledScience For The Blind a special unitwas designed for Mandel that trans-lates peak metering into audible"squawks." It is calibrated internally torespond to either 0, +4 or +8 peaks.From the front panel, Mandel canswitch any channel into any meter tocheck the levels. Depending on the na-ture of the sound, he may monitor for ahigher or lower level. In any case, whenthe threshold has been exceeded, a verynoticeable squawk can be heard. Thesound however, is emitted through aseparate monitor system so that themusical program will not be disturbed.

Certain other conveniences are builtin. Like braille markers (an embossedstick -on tape) to label channels on themixing console or to point out pre-setoptimum levels for invariable things

like sync tones. But frankly, Mandelsays, most things must simply be com-mitted to memory, because labelssimply do not fit on the narrow surfacesof most studio gear.

Another device Mandel showed me isnot strictly speaking a piece of studiogear, but it helps him organize his lifeand his studio schedule in a very effi-cient way. (Perhaps all studio ownersshould buy one of these gadgets!) Man-del was excited about his new specialpurpose lap -top computer-some-thing called Braille and Speak.

He explains: "Braille and Speak is a200K microprocessor that uses a 7 keyBraille format entry and has speechoutput. So I can carry it around in myjacket pocket, I can take notes, ap-pointments, phone numbers. It's reallyneat. It's only been around about a yearand it's revolutionized the way a lot ofus operate. We used to carry aroundeither slates and styluses and lots ofpaper, or machines that were kind ofclacky. Not only was entry a drag, but sowas retrieving the information.Nobody wants to carry around 300Braille pages so that they'll have theirschedules and their notebooks andtheir seminar notes to study and aphone book. This is really great. I'm re-ally happy with it!"

It was clear from my visit with MikeMandel that the microprocessor revo-lution has made a great impact on hislife. Living and working in the serenecreative environment of the electroniccottage has enabled him to utilize hisGod-given talents quite profitably, andin so doing, make many a songwritersdream come true. ElEg

BRUCE BARTLETT

AES Seminar on Live TheaterSound Design

At the November 1988 AESConvention, a group of ex-perts presented a seminaron live theater sound de-sign. If you have questions

about this topic, chances are you'llfind some good answers here.

The Chairman was Shelley Hermanof Accutronics Sound Company. Thepanelists were these:

Jonathon Deans has worked intheater sound for 16 years, and in thelast nine years designed sound for over20 productions of music and plays. He'sworked mostly in England, but hasdone some international productions.Mr. Deans was a sound engineer for theRoyal Opera House Covent Gardenand Autograph Sound of London.

Bill Hennig has 25 years experiencein technical media, and has done livesound for California Jam 1, three toursand a double live album for FrankZappa and the Mothers of Invention,the Earth Wind & Fire world tour 1975and 1980, Seasons at the GreekTheater, ibmmy at the AquariusTheater, Los Angeles Music Center,Almonson Theater, and Long BeachCivic Light Opera: resident designer1985 to present. He is a member ofIATSE for the past 23 years.

Al Cinescal is owner, sound de-signer, and chief executive officer of A-

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1 Audio in Hollywood, a major touring,- sound company handling such acts asz Charo, Ann Margaret, and Frank Si-

natra.c5; Abe Jacob is the "father of sound8 design in theater." He brought a hy-M bridization of techniques of concerta sound to the musical stage. Jacob

worked on such award -winning musi-S call as Hair, Jesus Christ Superstar,

Pippin, and Les Miserables. He hasdone concert sound for Jimi Hendrix,The Mamas and the Papas, and PeterPaul & Mary. Jacob is the executivesecretary and a founding member ofthe Theatrical Sound Designers Asso-ciation.

John Gottlieb is the resident sounddesigner at the Los Angeles TheaterCenter, Pasadena Playhouse, and the'Paper.

The panelists' comments have beencondensed and paraphrased for this ar-ticle.

What Are The Job Requirements OfA Sound Designer?

The function is to project and en-hance the performance on stage anddeliver it to the audience with the sameimpact that is happening on the stage,throughout the auditorium. The de-signer must be ready to make com-promises with artists, directors, andproducers.

Have hands-on experience withequipment before you do design work.Know your tools.

'By to understand the goals of the pro-duction people, and determine whattype of equipment will be needed to en-hance the performance. to stay upwith the state of the art but keep costsunder control.

Design a sound system which repro-duces in every part of the theater thesound as it appears at the microphones.Create special effects that enhance themood and character of the play ormusical. Ideally, the sound should be asgood as that of a home stereo system.

How Did You Contact ProspectiveCustomers When You Were FirstStarting?

I walked in the front door of a fewtheaters at the right time when theyneeded somebody. I convinced themthat I knew what I was doing and sub-mitted a bid.

How Do You Determine Your Fee?

The fee is based on theater size andbudget-normally $2000 to $3000 for a700 -to -1000 -seat show, with about onemonth pre -production.

What Is Your Procedure After BeingHanded The Script?

Very early on, become a part of theproduction team by talking with thedirector and set designer. You inte-grate the speakers and microphoneswith the set. Fight for what you want; beaggressive about speaker locations.Advise the producer about what is re-quired for the show and what it willcost.

How Long Do You Follow ThroughWith A Show?

At least all the way through pressnight. Normally you stay until the con-clusion of the show's run. Check thatthe operator is following your designand ask about problems.

What Are Your Considerations ForShows That Go On The Road?

We make our own cables, put connec-tors on everything, and carry our ownpower distribution. We set up in ourown shop first, and do a dry run with allthe equipment.

It's important to make the speakersystem flexible enough to interfacewith any environment. Carry differenttypes of speaker systems for differenttheaters.

Rely on your own equipment-as-sume that none of the theater's equip-ment works. However, many largervenues now have well -designed sound -reinforcement systems.

Do You Specify Mic Brands,Speaker Placement, Etc., Or JustSet Overall Goals And Let TheTech People In The TourCompany Determine TheHardware And Placement?

Specify every detail. It's yourname on the line. However, youmay have to make some changes orcompromises.

When You Specifs Do You IncludeThe Equipment Of The TourCompany And The Theater?

You can't count on the theater'slist ofavailable equipment, some ofwhich may not work or may notexist. Whenever possible, backyourself up by specifying newequipment.

How Do You Handle One -TuneEvents?

Take all your equipment, includ-ing lots of spares. Keep the systemsimple, so that when you set up, youhave time to listen and experimentwith speaker locations.

How Do You Decide WhatRecorded Music To Use With TheDrama?

Collaborate with the director.Ideally, you can take suggestionsfrom each other, but sometimesyou just follow the director's ideas.

Do You Prefer Sound Effects ToBe live Or Recorded?

I prefer recorded because a tapepunch-up is more reliable. Formore realism, it helps to put aspeaker where a person perform-ing the effect would have been.Stick to either live or recorded ef-fects, because switching back andforth can be distracting.

Live gunshots and some doorslams are much more effective live.A live musician can be amplifiedover the main system.

Do You Record Your Own Effects OrUse libraries?

I borrow from someone else's large,expensive library. It often helps tomodify or layer the stock sounds.

For Sound Effects, Do You UseOpen -reel, Cassette, BroadcastCartridges, Or A Digital StorageMedium?

It depends on the show. For a showwith many cues, you can use two orthree open -reel machines and a tapeoperator. A simple production can usecarts. The standard is the NAB car -

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tridge recorded by a production house.It's easy to use, easy to cue up correctly,and has mechanically quiet operation.

I've used a sampler for a ping-ponggame.

Do You Play Sound Effects Over TheMain House Speakers Or OverStrategically Located Speakers?

I put a speaker where the sound issupposed to be coming from, and playthe effect through that speaker. It'smore realistic and less distracting.

Often the on-stage volume of the ef-fect is too loud for the actors, so I try toaim the speaker at the audience andaway from the actors.

If the effect is the sound of the actor'sthoughts, I play it through the housespeakers.

What Are Your Comments OnWireless Microphones?

These days, wireless mics are often anecessity. That's because the audiencehas come to expect better, more intel-ligible sound-like a home stereo sys-tem. Also, the actors often must

compete with loud background music.In a 3000 -seat house, unless youcompletely isolate the orchestra, youmust use wireless body mics-not areamics. Musicals usually require bodymics; plays do not always require bodymics.

The goal is to have unnoticeablesound reinforcement. So if the leadcharacter has a wireless mic, all theother main actors will need one too, toavoid an obvious change in sound qu-ality.

You must train actors in wireless mictechnique. Make sure they project(talk loudly), and have them try to keeptheir volume relatively constant. Don'tlet them swap mics with each other!

them to come to you with soundproblems.

Ninety percent of the mic problemsare mechanical-damage to the micro-phone element or connector. Affix themic in a harness or strap to limit itsmovements. Work with the actor in re-hearsal to work out unusual mic place-ments.

In the Broadway theater, the majorityof the wireless units are Sennheiser; inthe London theater, Micron seems tobe the main choice; in Los Angeles,Vega is a big name.

What Problems Arise When TwoActors With Wireless Lavalier MicsAre Close To Each Other?

You get phase cancellations, but thiscan be prevented by using only one micto pick up both people. Follow theblocking, turn mics up and down asneeded.

What Are Some Problems WithMic'ing The Pit Orchestra?

The musicians move their mics awayfrom where you placed them. It helps toclip a gooseneck mic to the musician'schair or music stand. A useful productwould be a microphone stand with abuilt-in music stand. You can clip micsto violins; just be sure that the musici-ans don't move the microphone. Havea second engineer on stage check themic placements before each show.

What "Area" Microphones Do Youlike To Use?

I don't use omnidirectional micro-phones, because they can't isolate thestage from ambience. I like AKGpreamps and mic capsules. I have usedAKG foot mics with CK-3 capsules.The Crown PCC-160 works great forpicking up tap dancing. It has a widefield of pickup, so sometimes you canuse fewer of them. You might wantsome mics tuned for taps, others forchorus or dialog. I like Sennheiser 421sfor reeds. Also I like clip -on mics forstrings, and Shure SM-57 and SM-58for general-purpose, wide -range mics.

I like the PCCs for general ambienceand vocal pickup. I like their pattern.Because they're physically flat, theytend to hide better.

Where And How Do You UseBoundary Microphones?

I use Crown PCC-160 mics across thefront of the stage. They are less than aninch high so you can hide them. Be-cause of its supercardioid patternwhich rejects ambient noise, the PCC-160 has succeeded the PZM. I mightuse PZMs for ambience mics above anorchestra.

If you have a chorus upstage, youmight use a shotgun to pick them up lo-cally because you can't have a mic in themiddle of the floor.

I've seen plexiglass boundaries putaround a PZM, but it's like lookingthrough a fence.

It seems that the Crown PCC-160 isthe generally accepted microphone ofsound designers for front -of -stage lo-cation for area pickup. They seem tosound best with minimal EQ. You getadequate gain if the rest of the system isequalized properly. They have a lowprofile and are quite rugged. So forthose practical applications they seemto be the ones that are being used.You have to learn the show, have

specific mics up at specific times, makethem conform to the blocking. Haveonly one or two mics up at a time. Asyou turn up more mics, you add am-bience and it washes out the sound.

How Do You Use Shotgun Mks?I hang three or four AKG CK-8 or

CK-9 units on a scenery pipe upstage,or in the wings. This provides useablegain.

What Brands Of Musicians'Microphones Do You Like?

My favorite handheld dynamic is theSennheiser 431. The performers seemto like it. The AKG 535 seems to be agreat mic.

For the orchestra, I like Neumann,AKG, Shure, Sennheiser-whatever'sbest for the job. If the orchestra is in aseparate room, there's more freedomto use mic techniques like those in a re-cording studio.

When You Equalize The House, WhatSort Of Curve Do You Prefer?

I used a C -weighted curve for musi-cals. I like the Source IndependentMeasurement (SIM) system by MeyerSound Labs.

The general procedure is to play pinknoise through the system, run aroundwith an Ivie 1/2 -octave analyzer, and seta desired curve. Then play a CD thatyou're familiar with and re -equalize.You still need the pink -noise curve fora reference, but there are phase cancel-lations and standing waves that don'tcome out in the curve adjustment-you have to use your own judgement.You might use one type of equalizationfor foot mics, another for body mics.

I use the Ivie analyzer to set uniformSPL in the room before I set EQ.

Over -equalization can seriously de-grade the sound quality. No EQ is bet-ter than too much.

The first step is to have a correctspeaker system. We've had success withMeyer Sound Labs speakers becausethey are consistent. Once you find asound you like, the SIM lets us recreatethat same sound from one venue to thenext.

Notching out feedback frequencies iseffective for a fixed installation, but notfor a show on the road.

Describe The Effects Devices YouHave Used And How You Use Them.

The Lexicon 480 is brilliant-fun-alovely machine. Before that, the 224was good, and the PCM 70.

Gating is difficult in live theater be-cause the ambient sounds open thegates.

The Drawmer noise gate is good, as isthe Brooke -Siren compressor/limiterin de-ess mode. So the dbx de-esser.

I delay the wireless mics so that theaudience localizes the sounds at the ac-tors, and I de-ess the speaker signal sothat it's less distracting.

The Yamaha SPX -90 mutt:pie-ef-fects promssor has much flexibility,and is good for lower budgets.

What Are Your Desired Features InMixing Boards?

It's helpful to have input displays thatpre -warn you of trouble before yousend the sound to an audience. Polar-ity -reverse switches and group matrixarrays are useful.

Reliability is most important. Theboard also should be quiet and humanengineered.

The $230,000 Cadec board is a pro-grammable theater console, useful forlong show runs. The Yamaha PM -3000is very reliable and is easy to set upquickly. The Yamaha DMP-7 is pro-grammable.

Besides Reliability, What OtherFeatures Are Important In A PowerAmplifier?

Resettable levels and signal status in-dicators.

What Are Your Criteria For SelectingSpeakers?

They should be inconspicuous andhave a flat frequency response. Con-trolled dispersion is important. TWo60 -degree horns, aimed carefully, canproject sound to the audience whilekeeping sound off the thrust stage.

The speaker should sound the sameat low and high levels. Multiple hornsystems should perform well at the out-ermost areas of their patterns.

An integrated, protected speaker sys-tem (like Meyer Sound Labs) is morereliable.

I go with JBL sometimes because theysound good at low levels.

How Do You Get The BoardOperators To Do What You TellThem?

Tell them a story to give an image ofwhat sonic impression you want. Knowyour operators and work with them sothat they think the same way you do.

How Do You Relate To HousePersonnel In A Publicly OwnedAuditorium?

Listen to and respect what the houseperson has to say.

Seek his or her advice regarding whatwill or won't work.

What About Unions?

The sound designers' union 922 setsup rules that protect individuals and setsalaries. Don't expect house unionpeople to work at a breakneck paceevery day-they do hard work and haveto pace themselves.

In Using Delay To Move TheApparent Source Of Sound To TheActon If You Use Too Much Delay,You Lose Intelligibility. How ManyMsec Delay Do You Use?

I use 15 msec delay for an average -sizeproscenium arch. This localizes thesound at the actor, which helps theaudience sort out what the differentcharacters are saying, and prevents thesound system from calling attention toitself.

Does The Producer Give You ABudget, Or Do You Tell The ProducerWhat Your Required Budget Is?

It's done both ways. If you can't do agood job with the producer's budget,and that budget is inflexible, it's betterto turn down the job rather than riskingyour reputation by specifying an inade-quate sound system.

IAN "MACK" MCKENZIE

Jagger Down Under

1t's wonderful the way fateworks! There I was, lying inthe sun in the backyard,wondering what the futureheld for a recording en-

gineer like myself after a hectictwenty years.

Having recorded my fair share of topAussie bands, and the fact that I had afamily of seven which made a jauntoverseas next to impossible, Iwondered what the future couldpossibly hold.

Well, the answer came with a very ex-cited call from the Metropolis studiostelling me that Mick Jagger's manage-ment was looking for an engineer to re-cord a live television special whichwould include some studio work, andwas I interested in submitting my workreel and bio? Was I interested!

A NEW PROJECT

Instantly the images of an early retire-ment vaporized and I was madly rum-maging through old audio and videotapes of live recordings I had done.Should I include old stuff like MikeNesmith live at the Palais or Sports livefrom Bombay Rock?

After a lot of listening, looking anddiscussion with the team at MetropolisAudio, it was decided to include onlyrecent material I had done, such asNoiseworks which I recorded live atSelina's nightclub in Sydney, and theLittle River Band concert which wasbroadcast live from the opening ofWorld Expo 88 in Brisbane.

Well, I guess by now you've figuredout that, much to my excitement, I gotthe gig. After the euphoria had dissi-pated, the team of Em Rose, IbmKehoe and myself set about organizingthe event.

co

2 Ian "Mack" McKenzie is the ChiefCI Engineer/Director of Metropolis

Audio Pty. Ltd., South Melbourne,oco Australia.

The special was to have three mainelements. The b ul k o f the special was tobe videotaped at the MelbournelennisCentre. This venue has 360 -degreeseating for 15,000 and good acoustics,making it ideal for television. Then twoor three songs were to be filmed at theCorner Hotel, a club in Richmond, asuburb of Melbourne. And, finally,some footage of the song "Party Doll"was to be shot at Broken Hill in out-back Australia to give the special a"downunder" feeling.

After discussions with 'Ibny Blanc,the sound man for the Mick Jaggertour, we decided to run 45 channelsfrom the stage to the Metropolis AudioOB van. The van has a 40 channel Har-rison series 4032 with two MCI 24-track recorders, so we added a Yamaha1800 desk to handle the extra lines.

We ran the 25 drum mics, bass, andstereo keyboard feeds into the Yamahaand the vocals and guitars into the Har-rison. This left enough room on theHarrison to use for monitoring onlyand negated the "do we use the EQ forthe mic going to tape or keep it for themonitor?" problem.

We then combined these channels to21 tracks allowing two for audience andone for time code being supplied by thevideo van. All inputs to the MCI re-corder were split and sent to the audiobooth in the video van where a roughmix could be done.

I decided to run at 30 in./sec. usingDolby A noise reduction as there wassome quiet acoustic numbers in theconcert. This meant I could record Jag-ger's vocals at quite a low level and notbe concerned about tape noise or dy-namics. I didn't want to use any limitingon Jagger's vocal as I was already con-cerned about the compression factor ofthe Sony radio mic he was using.

A SMALL PROBLEM

The recording of the Friday and Sat-urday night concerts went without anyproblems, except for an over -enthusi-

astic guitar roadie who tested a spareguitar radio transmitter while the mainone was in use and they cancelled eachother out, resulting in a missing acous-tic guitar in the first half of "PartyDoll."

We took Sunday off to listen to therough mixes and work out the plan ofattack for the following week. As itturned out, the performances on bothnights were great and "War Baby" waschosen from Friday and the rest fromSaturday. On Monday we arrived atMetropolis Audio studios ready tobegin the post -production.

The heart of Studio One is a 6000 ser-ies SSL console. Hanging off this werea MCI 24 -track machine, 2 Sony 3/4 -inch U-matics for playback, a Sony3324 digital machine, and ATR center-

track timecode machine to mix downto. All these machines were connectedto a sophisticated synchronizer called"Editron." The reason for two U-mat-ics was to display the edited pictures onone monitor and the ca me ra , wh ich wason Jagger all night, on the other. Thismeant that if we had a problem withvocal quality due to the radio mic drop-ping out we could repair the track in thestudio and keep lip synch.

The opening title's music had alreadybeen recorded in Los Angeles. Thetempo was a bit slow to use for the endcredits, so first up we set about record-ing a faster version of the same piece.

INNOVATIVE SOUNDS

While I programmed a simple drummachine pattern for the click track,Simon Phillips, the band's drummer,set about hitting everything in sightlooking for that elusive rikitty ticksnare sound. He found the timber floorin the third live room to be just thething.

Meanwhile, Jimmy Rip had removedhis boots and he too was hitting every-thing with them, looking for a kicksound. It was agreed that "cowboy

Figure 1. The legendary Mick Jagger pictured with engineer Ian 'Mack" McKenzie in Metropolis Studio One during the finish-ing post -production touches on his television concert program for the Channel Nine Network, 'Mick Jagger: Deep DownUnder "

boots banging on guitar road case"made the ideal bass drum thud.

So with Simon on his knees playingfloor, and Jimmy playing guitar case,the drum track was recorded. Joe Satri-ani and Jimmy then overdubbed someguitars and Jagger played someharmonica through a mic plugged intoa Rockman on total distortion for alittle rough edge.

'Iliesday saw us repairing the missingguitar on "Party Doll," then startingthe mix. I kept all effects in the mix to aminimum, relying more on theaudience mics to provide the main am-bience. Thro Lexicon 480Ls, an AMSRMX16 and a couple of KorgSDE3000 delays were the only extrahelp needed.

'lb everyone's horror, when we cameto mix the Broken Hill part of "PartyDoll," the worst fear of any sweetening

session was realized! There was nosynch and the 24 -track MCI kept get-ting further ahead of the pictures. Iaverted major panic by explaining thatone of the features of the Editron syn-chronizer could save the day.

This clever piece ofequipment allowsyou to line up the start of the picturewith the start of the audio and mark it.Then you line up the end of the picturewith the end of the audio, and Editronwill calculate the capstan speed of theMCI to smoothly and imperceptivelyslew between the two points. It really isa fantastic feature and has saved manypotential disasters.

MICK'S ENTHUSIASM

By Friday we were running a bit be-hind schedule and the band had toleave for Adelaide. Jimmy decided tostay behind and help finish the mix.

Then, much to my surprise, Mickwalked in and said, "Hey you guys, youcan't get rid of me that easily." Mickwas very much a part of the team andhis tireless enthusiasm rubbed off oneverybody, making the sessions a lot offun and very rewarding.

I was also amazed at Mick andJimmy's stamina. As 5am approachedand my assistant, Doug Roberts, and Istarted to fade, the guys were out in thestudio playing their 25th game of tabletennis, and I don't mean just tappingthe ball over the net. These guys werereally working out!

We transferred the final mix at 7am.Jimmy and Mick flew out on a charterflight to Adelaide, and I went home tocontemplate what the future held for arecording engineer like myself after ahectic twenty years and two weeks!

RANDY HOFFNER

CMCD

gayaeiva 44444)AUDIO EQUIPMENT INTERFACING: IMPEDANCE AND LEVELS

The designer of an audio system orfacility, large or small, must decide howthe separate components of that facil-ity will interface to one another. Opti-mal functioning of any audio systemrequires that when the system is con-structed, careful consideration begiven to such factors as electrical powerdistribution, grounding and shielding,and to the subject of this column, theinterconnection impedances and sig-nal levels employed.

When video equipment in intercon-nected, there is but one standard im-pedance and one standard signal levelto use, but when audio equipment in in-terconnected, the system designer ispresented with options. Professionalaudio interface schemes have variedthrough the years, depending upon thedesign characteristics of availableequipment and the nature of the sys-tem under consideration.

TWO PIIILOSOPIIIESThere are two fundamental audio in-

terconnection philosophies: powermatching and voltage matching. Powermatching evolved from the early days ofbroadcasting, and the nature of audioequipment design at that time. An ex-ample of power matching is the 600ohm system that developed from earlytelephone company practice. A givenpiece of audio equipment has an out-put impedance of 600 ohms, and is con-nected to another piece of equipment,which has an input impedance of 600ohms. A 600 ohm source is terminatedwith a 600 ohm load: a matching termi-nation. A matching termination pro-duces maximum power transfer, adesirable objective for equipment in-corporating vacuum tube electronicsand transformer coupling, but not nec-essarily required or desirable withtoday's solid state audio equipment. Italso attenuates the open -circuit outputvoltage of the source by 6 dB, or one-half, thereby adding to the drive re-quirement of the output stage.

When long audio lines are used, cablecapacitance becomes a significant fac-tor, producing substantial highfrequency attention in a 600 ohm sys-tem. Reducing the system impedanceto 150 ohms solves the cable capaci-tance problem for lines of a length thatmight be encountered within mostaudio facilities, even very large systemssuch as those of a television network,for instance. The largest audio facilitywould generally not have many cablesthat exceed 1000 feet in length, and ca-bles of such length present capacitiveloads that may be overcome using 150ohm power matching. 150 ohm powermatching does, however, require highcurrent drive capability from audiooutput stages employing it.

Standard practice for telephone com-pany loops, which usually exceed 1000feet, and in fact often traverse distancesin excess of a mile between amplifiers,is to use 150 ohm impedance on theloop itself, translated to 600 ohms atthe interface points at either end. Thelengths of telephone company cablesare such that cable capacitance causeshigh frequency roll -off even at 150ohms. The equalizers on telco loopscompensate for high frequency roll -offby attenuating the low frequencies alike amount, and the result is flatfrequency response, but substantialloss in signal level, which is made upwith amplification.

'Iblco loops are- of such length thattransmission line effects are exhibitedat audio frequencies. Ransmission lineeffects require impedance matching toprevent signal reflections. Signal re-flections produce "ghost" images invideo, while their results in audio sys-tems are frequency response aberra-tions and comb filter effects.Ransmission line effects may be disre-garded within even a very large audiosystem, because transmission linecharacteristics do not come into playuntil cables reach a length of aboutone -tenth of a wavelength. One -tenthof a wavelength at 20 kHz. the highest

audio frequency of interest, is about amile. So while the telephone compa-nies must be concerned about trans-mission line theory in audio cables, thedesigner of any conceivable audio sys-tem within a single location may disre-gard such effects.

The second fundamental intercon-nection philosophy is voltage match-ing. Voltage matching employs a lowoutput source impedance, typically 50to 100 ohms, and terminating im-pedances that are sufficiently high to beconsidered "bridging" with respect tothe source. Input impedances for thistype of equipment commonly rangefrom 10 to 50 kilohms. In a voltagematched system the open -circuit volt-age of an output stage is attenuatedonly very slightly, if at all, when the loadis connected. Contemporary solid stateelectronic design has produced vir-tually universal compatibility with thevoltage source concepts of low -im-pedance outputs and high -impedanceinputs, and this is true of much trans-former -output equipment as well astransformerless.

Along with the two impedancephilosophies, standard audio signallevels vary as well. The audio leveltraditionally used in a 600 ohm powermatched system is +8 dBm. The term"dBm" specifies a ratio relative to a ref-erence level of one milliwatt, in any im-pedance. One milliwatt is apower level,and a given power level producesdifferent voltages across different loadimpedances. Thus 0 dBm, one milli -watt, produces 0.775 \inns across 600ohms, or 0.387 Vrms across 150 ohms.Ranslating some common referencelevels to voltages, +8 dBm/600 ohms =1.95 Vans + 10 dBm/150 ohms - 1.224Vrms and +4 dBm/600 ohms = 1.228V.. Voltage matching introducesanother unit of audio level measure-ment, the "dBu" specifies a ratio withrespect to a reference voltage of 0.775V,,,,s without regard to impedance. Themost common reference level used in

voltage matched systems is +4 dBu, or1.228 V..

SYSTEM PREFERENCEThe power matched systems still in

use are relics of the vacuum tube era,and are anachronisms in the 1980s. It isbecoming standard practice all overthe world to use voltage matched audiointerfacing. Here are some specific rea-sons for preference of voltage match-ing to power matching:

1) A substantial increase in band-width is realized on a system level. Thebandwidth limiting factor in an audiosystem employing modern solid stateequipment is not the electronics, butthe cable.2) Interconnection and termination

is faster and easier because there are notermination resistors to deal with.Level problems caused by missing ordouble terminations are eliminated.

3) Smaller signal current flow in ca-bles, reducing the potential forcrosstalk.

4) Capacitive coupling between ca-bles is reduced because of the lower im-pedance held on lines.

5) Multiple loads may be fed from thesame source if necessary. Thn, 10kilohm loads still present a bridgingimpedance to a 50 ohm source. Suchmulting is not generally recommendedas a system wiring practice because ofreliability considerations, but may beused when patching.

6) Lower system distortion resultsfrom the reduced loading factor. Thegreater the load on an output stage, themore distortion it generates. In partic-ular, driving a 150 ohm load taxes out-put stages to their utmost, and requiresfar more drive current than driving ahigh -impedance load.

7) Greater headroom and thus widerdynamic range results from drivinghigh impedance loads.

8) Voltage matched systems consumeless power than power matched sys-tems, and thereby reduce power supplyrequirements.

Frequency response sweeps of cir-cuits representing the common inter-connection schemes illustrate theincreased system bandwidth availablewhen voltage matching is used. First,consider a system consisting of a 600ohm source feeding a 600 ohm load via1000 feet of twisted -pair cable withshield, representative of audio cable incommon use today. The capacitancebetween signal -carrying conductors ofsuch cable is around 30 picofarads per

foot. This capacitance creates a lowpass filter, and for the 600 ohm systemthis filter's -3 dB point falls at about 14kHz, with the response at 20 kHz beingrolled off about 5 dB. Perceptible roll -

off begins at frequencies as low as 4kHz.

A sweep of a similar system withsource and load impedance reduced to150 ohms reveals frequency responseflat to 20 kHz with the -3dB point fal-ling above 30 kHz. The reason forchoosing 150 ohm systems over 600ohm systems for long cable runs is ob-vious. The 150 ohm power matchedsystem provides sufficient systembandwidth, even with 1000 foot cables.However, at 30 pf per foot, 1000 feet ofcable presents a capacitive load of 0.03pf, which appears in parallel with theload resistance, further taxing the out-put stage and generating more distor-tion. When the source impedance isreduced to 50 ohms and the load im-pedance is raised to 10 kilohms, the -3dB point is well above 100 kHz. Thecable capacitance appears in parallelwith the much higher load resistance,and is driven by the low impedancedriver, greatly reducing the demandson the output stage.

It may appear that the lower thesource impedance the better, but infact if the driving impedance is loweredsufficiently, high -frequency peakingwill be seen. The optimum source im-pedance for voltage matched systems isabout 60 ohms, and the 50 to 100 ohmsfound in typical audio equipment isperfectly satisfactory.

When all the above is considered, it isnot difficult to reach the conclusionthat voltage matching is preferable topower matching for interconnection oftoday's audio systems.

STANDARD LEVELThe common reference level for volt-

age matched systems is +4 dBu, or1228 Vrms. Virtually all modern pro-fessional audio equipment is compat-ible with this level, which is in fact thestandard level used in recordingstudios, and increasingly, in broadcastaudio systems. It is 4 decibels lowerthan the standard telephone companylevel of +8dBm, which is the referencelevel traditionally used in 600 ohmbroadcast systems. The noise floor ofall modern professional audio equip-ment is sufficiently low that excellentdynamic range maybe achieved using areference level of +4 dBu. Most audioelectronics of recent vintage is capableof at least +24 dBu undistorted output,

providing 20 dB of headroom abovereference level.

Some audio facilities require subsys-tems designed for power -matchedoperation. For example, telephonecompanies often use passive equalizerswhich require a true 600 ohm source(not a low impedance source capable ofdriving a 600 ohm load) to produceproper frequency response.

With the above exceptions noted,voltage matched audio interfacing isthe interconnection philosophy ofchoice, and +4 dBu = 1.228 V. hasbecome reference level of choice forprofessional analog audio interfacing.Implementing such a philosophy isrelatively straightforward for equip-ment with balanced transformerlessinput and output stages, which arerapidly becoming the rule rather thanthe exception. Equipment with trans-former inputs or outputs may fall intoseveral categories. live 600 or 150 ohmoutputs may be source -terminated intheir characteristic resistance, makingthem appear as voltage sources to theoutside world. Transformer outputswhich are actually low -impedancesources, for instance, transformers de-signed to drive 600 ohm loads, buthaving an actual output impedancearound 100 ohms, often may be usedwithout terminations. Such equipmentshould be checked for frequency re-sponse in the unterminated modebefore being used in th is way, However,because termination may be requiredfor proper frequency response.

Direct connection of multiple loadsto a single source is permissible whenvoltage matching is used. This is notrecommended as a distribution prac-tice, although it may be used whenpatching. Connecting multiple loads toa single output can compromise relia-bility, because if one output fails or be-comes shorted, all loads are affected. Itis prudent therefore, to isolate loadswith multiple distribution amplifieroutputs. If audio distribution amplifi-ers use 60 ohm balanced output splits,each output is protected with about 60dB of isolation against a backfeed fromany other output, and shorting any out-put results in a negligible voltage dropon other outputs.

It is apparent that there are manyadvantages to using voltage matchinginterface techniques in audio systemdesign. Such design will result in im-proved technical operation and re-duced power consumption. 7 7

1989 Editorial Calendar

JAN/FEB db Looks at the Electronic Cottage going upscale!

A broadcast report on the Seoul Olympics

GUIDE: Speakers: performance & monitor

MAR/APR db Looks at the Sound Reinforcement Scene: theory,

layout, and construction

GUIDE: Power Amplifiers

MAY/JUNE db Looks at The Windy City

GUIDE: Consoles & Mixers

JULY/AUG db goes on tour with the Major Touring

companies

GUIDE: Tape, tape recorders and accessories

Microphones

SEPT/OCT db looks at the Boston Recording Scene

GUIDE: Signal Processing Equipment, Part I

NOV/DEC db Looks at The West Coast & Hawaii

GUIDE: Signal Processing Equipment, Part II

Studio Accessories

THE SOUND ENGINEERING MAGAZINE

BUYER'S GUIDE:

Power Amplifiers

Introduction to the Charts

We've tried to make the charts of amplifiers as self-explanatory as possible, with slantingheadlines on each column that explain what we wanted to show you.

These charts represent entirely what each of the respective manufacturers have sent us inresponse to our (sometime repeated) requests. You will also see that there are numbers ofblank sections within the charts. If they don't have a specification available, we can't list it.But note that many do not have anything under the Features column. This column is where wehave invited each manufacturer to state, in as few words as possible, what is special about theproduct. You can safely assume, then, that when this column is blank, it is because the manu-facturers told us nothing.

Note also that we ask for amplifier continuous power not only at the traditional 8 and 4 ohmresistive loads, but also at 2 ohms. As you know, when you parallel speakers, the load ishalved. Accordingly, in the real worlds of studio monitors and headphone lines, and the evenmore real world of performance and stadium systems, effective loads back to an amplifier canwell be 2 or 3 ohms. Since modern solid-state amplifiers can handle such loads successfully, weask each manufacturer for this specification. Note that not all give it. It's therefore safe toassume that if it is missing, the amplifier may not be reliable at low loads.

Distortion at normal and full power ratings is also specified. While many amplifiers today canboast of almost vanishing distortion, remember that if you will be pushing an amplifier hardup against its rated power and beyond, distortion will then be rising rapidly. No audio productis really made to be abused, and amplifiers are no exception.

One group of important specifications deals with dimensions and weights. Amplifiers, particu-larly high -power ones, are not lightweights. A few racks can have weights adding up rapidly.

Finally, the price. What we have asked each manufacturer for is the suggested retail price.Different retail dealers establish their own.

On to the charts...

ALTEC LANSING CORPORATION1268

1269

1270C

1407A

1415A

2200A

2 60 100

2 120 200

2 220 400

75 75

1 150 150

ver

20- 03 .03 .3 .1 5- .7820k 100k

20- 03 .03 3 5- .7820k 100k

3.5

19

10

33 $1330.00 Includes choice of XLR,and terminal imputs, 5 -way bind-ing posts, LEDs, protection.

3.5 47 $1430.00 Choice of XLR, V -inch and ter -19 minal inputs, 5 -way binding posts,14.75 peak and protection LEDs.

20- 05 .05 .3 7- .78 5.25 51.5 $185000 Choice of XLR, '4 -inch and ter -20k 33k 19 minal inputs, peak and protection

15 LEDs, two -speed fan cooling.

20- 01 01 .2 10- .78 5.2520k 30k 19

12.5

24.2 $556 00 Includes XLR (male and female),phono and terminal inputs, directand kformer output, protection.

20- .01 .01 .2 10- .78 5.25 30.8 $680.00 XLR (male and female), phono and20k 30k 19 terminal inputs, driver prof -

12.5 action relay, convection cooling.

20- 5 .25

15k

2204A 4 75 150 300 20- 5(4ch) (2ch) (1ch) 15k

10- .61 7 70 $5100.00 Eight 75W power amp modules that30k 19 can be configured for numerous

17.4 output combinations up to 600W.

.25 10- .78 5.25 31.5 $1750.00 Four 8 ohm/75W power outputs that30k 19 can be paralleled and/or bridged,

18 X -former isolated inputs.

9444A 2 200 300 10- .05 .05 2 10- .81 5.25 39 $958 00 Electronically balanced XLR or70k 85k 19 terminal inputs, octal socket,

12.75 peak and protection LEDs.

ASHLY AUDIO INC.F ET -200 2 120 190 225 20- 004 .01 004 .05 20- 1.4 3 5 37

20k 20k 19

16

Modular construction forced aircooling, LED meters.

F ET 500 2 300 500 675 20- 004 .01 004 .05 20- 1.7 5.25 60 Stable into any load mono/bridge20k 20k 19 modes,brown-out proof.

16BGW SYSTEMS INC.7500T 2 200 250 20- .05 3- 1.22 5 25 36

20k 100k 17 5

105

SPA -1 2 250 400 600 20- 7.0520k

SPA -3 2 250 400 20- 7.0520k

Modular construction barrier -strip terminal, plug-in crossover.

5 25 41 Signal processing subwoofer amp19 parametric EC.137

525 4319

13.7

750FG 2 280 4.50 20- .01 .06 20- 1.5 7 5520k 20k 17.3

12.9

G TA 2 350 600 900 20- .03 20- 1.48 7 72

20k 20k 17.514.5

Signal processing amplifier,active, balanced inputs.

Low feedback design, available ina studio version.

Grand touring amp, solid state DCspeaker protection.

G78 2 275 400 BOO 20- 03 20- 1.48 5.25 50 Accepts 2 BGW crossover cards20k 20k 19 for bi or triamping.

13

B5001 2 300 450 850 20- 05 20- 1.8 5.25 50

20k 20k 19

13.8

Cost-effective version of GTBdesigned for fixed installation

CARVIN CORPORATION -See our ad on page 15FET 400 2 100 200 20- 006 1 20- 1 5.25 31 $499.00 MOSFET technology, speaker pro -

20k 20k 19 tion, road -worthy construction.10

FET 900 2 200 300 450 20-20k

CREST AUDIO1001A 2 55 85 20-

20k

1501A 2 90 150 20-20k

3000-1 2 260 475 720 20-20k

4000-1 2 340 600 900 20-20k

7001 2 560 810 850 20-20k

8001 2 750 1225 1400 20-20k

PL -400 2 320 600 20-20k

FA -800 2 240 400 20-20k

CROWN INTERNATIONALMacro 2 235 325 340 35kTech 600

Macro 2 525 800 1200 35kTech 2400

Micro 2 320 485 600 35kTech 1200

D-75 2 35 45 60 35k

D -150A 2 95 150 108 36k

DC -300A 2 175 295 320 35k

PSA-2X 2 285 380 685 50k

PS -400

dbx, INC.

2 165 285 225 35k

BX1 2,3 100 200 325 20-or 4 (4-ch.) 20k

-See our ad onELECTRO-VOICE, INC.AP2600 2 200 300 7-

.006 .1

.04 .04 .08 .06

.06 .06

.03 .03

.03 .03

.01 .01 .05 .05

.015 .015 05 .05

.01 .01 .01 .1

.01 .1

.001 .06

.001 .06

.001 .05

.001 .05

.01

.01

.01

.01

.01

page 7

.01 .001 .05

.01 .001 .05

.01 .001 .05

.01 .001 .05

.01

20k

.03 .05

20- 1 5.25 35 $669.00 Same features as the FET 400,20k 19 yet has 900 watts total output

10

20- .42 10.5 17 $679.0020k 19

1.75

20- .81 10.5 17 $839.0020k 19

1.75

1- 1.1 5.25 48 $1589.00 Includes signal present LEDs.50k 19

11.5

1- 1.27 5.25 56 $2189.00 Includes signal present LEDs.50k 19

13

20- 1.4 3.5 49.5 $2589.0020k 19

15

20- 1.75 5.5 80 $3189.0020k 19

15

20- 1.2 3.5 38 $1239.0020k 19

13

20- t.0 3.5 32 $879.0020k 19

13

20- .77 3.5 43 $1295.0020k 19

18

20- .77 3.5 80 $1995.0020k 19

16

20- .77 3.5 45 $1295.0020k 19

16

20- .81 1.7 13 $524.0020k 19

9

1- 1.19 5.2 27 $795.0020k 19

8.7

0- 1.75 7 45 $1095.0020k 19

9.7

20- 2.10 7 61 $1995.0020k 19

14.7

0- 1.78 7 54 $1019.0020k 19

10

20- 1 7 84 $2800.00 Reference quality amp, configur-19 able for two, three, or tour

24.5 channel operation.

.775 5.25 39 $999.00 Available with precision stepped0iCo

4VNstA .,1

cs`,e cP\C),00 v.)\ \A1

0\ \ c \ e`o,

c3,tits ,0 0,%4 cos(' Air,

-I -

cao" 10'* *PctSe \i" " Ws.d°" ve, 204' ce eN oIN t02. .00 cel ,tte 9.44 *9 Os cc'\ oci i'cs cc° cf$

HAFLER

85k 19

12 75

P500 2 225 400 10- 007 .007 .007 .002 20- 1.55 7 5360k 24k 19

13

P505 2 225 400 10- .007 .007 007 .002 20- 2.55 7 4860k 24k 19

13

P230 2 115 175 10- .005 .005 .007 .002 20- 2.55 5.25 2860k 24k 19

10.5

P125 2 62 4- Do s .005 .007 .002 10- 1.1 a 5 22200k 40k 19

9

INDUSTRIAL RESEARCH PRODUCTS, INC.DH4020 2 100 140 20- .02 .1 1 1.75 13.5

20k 19

14

INDUSTRIAL STRENGTH INDUSTRIES -See our ad on page 23PA700 2 250 400 10- 5 2 40

50k 19

13.2

INNOVATIVE ELECTRONIC DESIGNS, INC.6208 1 200 20- 5 .5 20- .9 6.1 2.4

20k 20k 2.1

12.7

6270 1 20- 5 .5 20- .9 6.1 2.3820k 20k 2.1

12.7

JBL PROFESS! ONAL6210 1 40 20- .1 .1 29- 8 6.5

20k 20k 8.52.75

6211 1 40 20- .1 .1 20- 8 8.520k 20k 8 5

2.75

6215 2 35 45 20- .1 1 1 20- 1.1 1.75 10.520k 20k 19

9

6230 2 75 150 20- .1 1 1 20- 1.1 5.25 26.3

20k 20k 19

11

6260 2 150 300 20- .1 1 1 20- 1.1 7 44.520k 20k 19

11

6290 2 300 600 20- .1 1 1 20- 1.1 7 6320k 20k 19

14

PASO SOUND PRODUCTSAlpha 130 2 200 10- .003 5- 1 5.33 28.5

40k 100k 19

13.5

Alpha 230 2 245 5- .008 5- 1 5.33 29.3100k 100k 19

13.5

Alpha 450 2 440 5- .008 5- 1 7.25100k 100k 19

19.13

Alpha 650 2 680 10- 008 0- 1 7.25 60.5

attenuators as model AP2600SA.

Balanced line, mono bridgeable,front level controls.

Mono bridgeable, level controls.

Balanced line accessory, monobridgeable, level controls.

Balanced line accessory, monobridgeable, level controls

$1042.00 100 kHz switching power supply,MOSFET high freq. output

$699.00 Bullt-in electronic X -over, bal-anced XLR Inputs, mono bridging,protection, automatic fan cooling

$783.00 Class D (switching mode) designcard type, greater than 80% ef-ficiency at full output

$783.00 200 watts Into 25 ohms or 70.7v,all specs at 25 ohm load. Bothamps have balanced outputs.

$295.00 Converts 4400 series or any other8 -ohm monitor Into self -contain -ed power system.

$330.00 Same as above and also includesactive balanced Inputs, but withmic/1ine selector switch.

8650 00 Active balanced bridging Inputcircuitry, rear -panel switch forbridge/dual mono or stereo.

$695.00 Same features as above.

$995.00 Same features as above.

$1495.00 Same as above yet also includesfan for cooling.

$376.00

$485.00

$899.00

$1485.00

%94.4

ScPC'SS 0'24

cp0. 9041. w$1°. .cv.,0 ANk0 Ocks) se. t:".4,1444.. 9iscs'904, e,os Ocu' Ns NS'° 9C7SS

i \CP 0', " ie.

PEAVEY ELL

40k 100k

L;CS -1200 2 350 600 20- .01 .03 5-

40k 60k

CS -1000 2 300 500 20- .01 .03 5-40k 60k

CS -800 2 240 400 20- .04 .03 5-

20k 40k

DECA 528 2 210 250 20- 0.0 0.0 .15 10-20k 20k

DECA 1200 2 325 800 20- 0.0 0.0 .08 10-

20k 20k

DECA 724 2 225 350 20- 0.0 0.0 .1 10-

20k 20k

M-7000 2 200 350 20- .01 .03 10-20k 30k

QSC AUD 10 PRODUCTS, INC.1100 2 50 70 90 40k .01 .01 .01 20-

20k

1400 2 200 300 40k .01 .01 .01 20-20k

1700 2 325 500 40k .01 .01 .01 20-20k

MX1500 2 330 500 40k .01 .01 .01 20-20k

MX2000 2 375 625 40k .01 .01 .01 20-20k

3200 2 110 140 40k .01 .01 .01 20-20k

3500 2 300 450 40k .01 .01 .01 20-20k

3800 2 375 600 40k .01 .01 .01 20-20k

RAMSA (PANASONIC)2WP9440 350 10- .06 .06 .06 .08 20-

60k 20k

WP9220 2 203 300 10- .06 .06 .06 .08 20-85k 20k

WP9110 2 100 150 10- .06 .08 .06 .08 20-85k 20k

WP9055 2 50 10- .05 .05 .05 .05 20-

115ic 20k

19

18.5

1.4 7 70 $1299.99 Plug-in electronic X -over capa-19 bility, transient -free turn on/17.75 off, thermal protection.

1.4 5.25 5019

14.13

1.4 7 54 $799.9919

13.5

1.0 1.75 12 $749.991914

1.3 3.88 3719

18

Plug-in electronic X -over capa-bility, transient -free turn on/off, thermal protection.

Plug-in electronic X -over capa-bility, DDT compression, fan -cooled, thermal protection.

Digital energy comversion amp,DDT compression, fan -cooled,MOSFET design.

$1399.99 Digital energy comversion amp,DDT compression, fan -cooled,MOSFET design.

1.0 3.88 37 $999.9919

18

Digital energy comversion amp,DDT compression, fan -cooled,MOSFET design.

1.4 5.25 47 $749.99 Fan -cooled, DDT compression,19 electronic X -over capability,16.5 transient -free turn on/off.

.83 1.75 12 $568.0019

7

1 5.25 3419

9.5

1 7 5719

10.8

1 3.5 471917.9

$798.00

$1098.00

$1098.00

1 5.25 75 $1498.001915.9

1 1.75 261914.6

1 3.5 5019

15.9

1 5.25 7519

15.9

1.23 5.25 7519

18.88

$958.00

$1488.00

$1938.00

$2090.00 Intelligent VI limiting, softoverload characteristics.

1.23 5.25 38.8 $1090.00 Has ability to drive high phase -18.88 angle, loads with ease.15.08

1.23 3.5 28.6 $840.00 Detented input attenuators with18.88 removable knobs.15.08

1.23 1.75 19 $590.00 Signal, peak and protect LEDs,18.88 XLR and phone inputs.13.13

RANE CORPORATIONMA6 6 100 150 20- .2 .2 5- .775 5.25 44

20k 80k 19

11

RENKUS-HEINZ, INC.P-1500 2 300 500 750 .1 .1 20- 1.55 3.5 40

20k 19

13.75

SHURE BROTHERS INC. -See our ad on Cover IV210 1 6 10 100- 1 3 100- 40mV 2.75 2.13

15k 15k 9.55.63

SOUNDCRAr it MEN -See our ad on page 37300X4 2,3 600 900 450 20- .05 .05 .008 .05 20- 1.0 5.25 60

or 4 205 300 20k 20k 19

14

PM860 2 210 315 450 20- .05 .05 .008 .05 20- 1.2 5 2020k 20k 8.5

14

450X2 2 210 315 450 20- .05 .06 .008 .05 20- 1.2 5.25 2820k 20k 19

11.75

900X2 2 375 675 900 20- .05 .05 .008 .05 20- 1.22 5.25 5920k 20k 19

16.5

RA7501 2 275 420 320 20- .05 .05 .05 .05 20- 1.21 7 4720k 20k 19

15

SPECTRA SONI CS701 1- 33 58 86 20- .05 .075 .025 .025 0- +5 2.5 .88

inf 20k 20k dBv 10

1.88

701BP 1- 122 172 200 20- .05 .075 .025 .025 0- +5 5 1.78Int 20k 20k dBv 10

1.88

7120 2 30 50 80 20- .05 .075 .025 .025 0- 0 5.5 2220k 20k dBv 19

14.5

712 2 100 100 100 20- .05 .075 .025 .025 0- 0 5.5 2420k 20k dBv 19

14.5

SUNNSPL7000 2 200 350 10- .005 .005 .1 .1 20- 1.23 5.25 40

50k 20k 19

15

SPL7250 2 160 250 10- .005 .005 .1 .1 20- 1.23 3.5 3050k 20k 19

14.5

STUDER RtvvX AMERICA, INC.A68 2 100 175 30- .1 17dB 5.25 48.4

20k 199.75

B242 2 200 230 400 20- .01 .01 20- 1.55 6 37.520k 20k 14.2

7.7

SYMETRIXA-220 2 20 20 20- .01 20- .5 1.75 9

40k 20k 19

8

YAMAHA CORPORATIONPD2500 2 250 380 500 20- .007 .007 10- 1.23 3.88 26.5

$1349.00 Built-in limiters, auto bridging,2 -speed fan.

$1750.00 Compact, rugged amp, featuresPower -Guard circuitry.

$125.00 Balanced mic Input, unbalancedline In -put, ext. 12V power.

$1299.00 Mufti -channel MOSFET, 2, 3 or 4channel mode indicators, frontpanel -mounted circuit breakers.

$599.00 Has high current design to allowstability with 2 ohm loads.

$849.00 High current MOSFET amp withbalanced or unbalanced Inputs.

$1599.00 Same as above.

$949.00 Class H signal tracking designfor maximum efficiency.

$108.00 A modular amp suited for bi, tri,multi -way, used in noise masking,broadcast, recording.

$216.00 Is two model 701s bridged togetherwith the same qualifications.

$595.00 A stereo rack -mount, self -contained power amplifier.

$760.00 A stereo rack -mount, self -contained power amplifier.

$799.00 Quiet, 2 -speed fan, delay on/off,protection, compressor.

$599.00 Balanced 1/4-inch/XLR, 5 -waybinding posts.

$2100.00 Low closed loop feedback, monobridgeable for 400W.

$3000.00 MOSFET drive transistors, 2separate power transformers.

$315.00 Phone and XLR Input, front panelheadphone jack.

$1545.00

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P2150

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P2075

P1150

PC1602

PC2602

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2 170 250 10-50k

2 100 150 10-

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170 250

100k

2 50 75 10-

50k

1 100 150 10-100k

2 160 240

2 260 400

50k 18.8818.88

.007 .007 10- 1.23 5.25 41.8 $895.0050k 18.88

18.88

.01 .007 10- 1.23 5.25 37.4 $695.00

50k 18.88

16.63

.01 .004 10- 1.23 5.25 33 $595.00

50k 18.88

16.63

.05 .003 10- 1.23 3.88 19.8 $495.00

50k 18.88

14.38

.005 .06 10- 1.23 5.25 28.6 $495.00

50k 18.8816.63

01 .015 10- 1.23 5.5 47.8 $995.0050k 18.88

17

.007 .015 10- 1.23 7.25 57 $1295.0050k 18.88

17

XLR and 'Xi -inch input Jacks,

binding post and 1/4 -inch out-put Jacks, forced air cooling.

XLR and 1/4 -inch input Jacks,

binding post and 1/4 -inch out -

put Jacks, forced air cooling.

XLR and 1/4 -inch Jacks, binding

post and 1/4 -inch output Jacks,

compact and light -weight

XLR and .25 -inch Input jacks,binding post and .25 -Inch out-put jacks, forced air cooling.

Comprehensive protection circuitryXLR in and through connectors,480 watts in mono.

Protection circuitry, XLR in andthrough connectors, model PC2802Mhas 26 -segment backlit LCD meters

The Buyer's Guides for 1989Save each one for a complete guide to the equipment necessary for

your studio!

JanIFebPerformance and Monitor Speakers

March/AprilPower Amplifiers

May/JuneConsoles and Mixers

JulylAugTape, Tape Recorders, and Access., Mics

SeptlOctSignal Processing Equipment, Part I

NovIDecSignal Processing Equipment, Part II, Studio Access.

Altec Lansing CorporationPO Box 26105Oklahoma City, OK 73126

Ashly Audio100 Fernwood AveRochester, NY 14621

BGW Systems13130 S. Yukon AveHawthorne, CA 90250

Carvin Corporation1155 Industrial AveEscondido, CA 92025

Crest Audio150 Florence AveHawthorne, NJ 07506

Crown International1718 Mishawaka RdElkhart, IN 46517

dbx, Inc.71 Chapel StNewton, MA 02195

Electro-Voice, Inc.600 Cecil StBuchanan, MI 49107

Hafler613 S. Rockford DrTempe, AZ 85281

ADDRESSES

Industrial ResearchProducts, Inc.321 Bond StElk Grove Village, IL 60007

Industrial Strength Industries13042 Moore StCerritos, CA 90701

Innovative Electronic Designs9701 Taylorsville RdLouisville, KY 40224

JBL Professional8500 Balboa BlvdNorthridge, CA 91329

Paso Sound Products14 First StPelham, NY 10803-1401

Peavey Electronics711 A StMeridian, MS 39301

QSC Audio Products1926 Placentia AveCosta Mesa, CA 92627

Ramsa (Panasonic)550 Katella AveCypress, CA 90630

Rane Corporation10802 47th Ave WEverett, WA 98204-3400

Renkus-Heinz17191 Armstrong AveIrvine, CA 92714

Shure Brothers222 HartreyEvanston, IL 60204

Soundcraftsmen2200 So. RitcheySanta Ana, CA 92705

Spectra Sonics3750 Airport RdOgden, UT 84405

Sunn6024 SW Jean Rd, Bldg DLake Oswego, OR 97035

Studer Revox America1425 Elm Hill PikeNashville, TN 37210

Symetrix4211 24th Ave WSeattle, WA 98199

Yamaha CorporationPO Box 6600Buena Park, CA 90622

dr-

New P1.044a4

QUAD BOX

The Mini Quad Box is a compactquad box for wireless microphone sys-tems. It is designed to house and cen-trally power up to four Vega R33 min-iature receivers. It also provides RFfeeds via a single antenna by means ofan internal multi -coupling system. Itoperates from 12 internal "C" batteriesor from external 12-24 volts d.c. Di-mensions are 5x7x8, and weight is 7pounds, 4 ounces.Mfr:- Professional Sound Corpora-tionPrice- $1275.00


PROGRAMMABLE TEST GEAR

The 3100B and the 3200B are pro-grammable audio signal generator/an-alyzers. Designed to exceed test equip-ment requirements in the 16 -bit digitalera, these units offer three distinctmodes of operation: manual withfront -panel control for troubleshoot-ing or design, built-in automation forquick equipment proofs, and completecomputerized test and measurementcapability using external, menu -drivensoftware. They are designed to beportable. This two -channel unified sys-tem will manually or automaticallymeasure operating level, frequency re-sponse, total harmonic distortion(THD) vs. level or frequency, SMPTEintermodulation distortion (IMD),signal-to-noise ratio (SNR), quantiz-ing noise, channel separation, phaseerror between channels, and wow andflutter measurements. Front -panelswitches, LEDs, and digital readoutson each allow usage as stand-aloneunits. When separated at remote sites,the generator sends FSK signals overthe audio channel being tested whichconfigures the analyzer for each test.Either or both units can be completelycontrolled and interrogated by a com-patible terminal or personal computer(PC). The 3100B generator uses digi-tally -controlled analog oscillators toproduce sine and square wave signals in

addition to SMPTE IMD, tone -burst,and sine/step waveforms. Sine wavesrange from 1 Hz to 102.39 kHz, withlow 0.0008 percent distortion, andsquare waves from 1 Hz to 50 kHz, witha rise time of less than 1µs. Internalcrystals ensure that frequency accuracyis within 0.03 percent for fixedfrequency and selected frequencysweeps. The generator will store 91

different front -panel test set-ups.Whether testing in a manual or auto-matic mode, recalling a panel set-upspeeds the procedure and ensures re-peatable test conditions.Mfr- Sound TechnologyPrice- $4250.00 (3100B)

$5495.00 (3200B)


i".ri

MATRIX MIXDOWN

The Mode11010MM is a matrix mixdown and monitor audio panel. Thespecifications include 10 inputs withelectronic balanced transformer, a 20K impedance, and XL type connectors.The unit has a three -stage system whichincludes the input stage with audio lineamplifier used to drive all ten 10 Kaudio taper pots. The summing stagecontains an audio line amplifier of thesame type used to sum all ten signals inChannel A. The output stage has tengain controlled transformer balancedaudio line amplifiers with XL type con-nectors. The unit's output is +24 dbm,with 0.25 percent THD, and -74 dbmnoise below +4 dbm. The power supplyis dual 523R (regulated ±24V at +11amp). One supply for operation andthe second for back-up in case firstsupply should fail (switchable). Thesize is 15-3/4x19x9, and the weight is 29lbs.

Mfr.- Opamp Labs, Inc.Price- $4500.00


RACK -MOUNT MIXER

The MAXXAM 8 + 8 is a rack -mount mixer with 16 input channels ina compact rack -mount configuration 6rack spaces high. Eight of the unit'schannels are designed to handle stereoinput signals, giving it the input capa-bility of a conventional 24 -channelmixer. The gain structure for all chan-nels is designed for line level inputs.The mixer includes two unassigned lownoise microphone preamps with XLRinput connectors and 1/4 -inch phoneassign jacks, thereby allowing the micpreamp output signals to be assignedto any of the input channels with a shortpatch cord. All input channels havepatch insert jacks. The unit has foursends, one of which is selectablepre/post fader on each channel. Thereare also four stereo returns. Channelfaders and the stereo mains fader are 60mm throw professional level. The ab-sence of channel EQ and use of 5532and TL072 op amps throughout resultin a very low noise unit.

tttip444644

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4666

Min- Biamp Systems, Inc.Price- $1499.00 Circle 63 on Reader Service Card

COAX MOUNTING SYSTEM

Built to address the needs of theprofessional sound contractor andsound installation market, the M4CoAx allows any of the company's PC400 Series high -frequency horns to becoaxially mounted directly in the cen-ter of a matching M4 PC 1500 Serieshorn with a PCMX mouth extension.Cluster design can be simplified and re-duced in size because the high -frequency horn can be located in themiddle of the mid -range horn, and im-proved directivity performance can beobtained at the mid -to -high crossoverpoint. If the crossover and delays aredesigned properly, it's almost as ifthere is one speaker that is capable ofgoing from 200 to 20,000 Hz. It is avail-able as a complete system with hornsincluded, or as a package including allmounting hardware and a specialbracket.

REFERENCE CHART

The Milli -Chart is a wall or table-top plastic -coated reference chartshowing the relationship between digi-tal -delay time settings and musicaltempos. It was designed to alleviate thetedious process of computing delaytimes with a stop watch and calculator.

SUBWOOFER SYSTEM

The Model SUB -152 bandpass sub -woofer system is designed to be used assub -bass support for full -range speakersystems. By restricting bandwidth, thebandpass design increases efficiency to106 dB (1w, 1M). Distortion com-ponents are attenuated, resulting incleaner, tighter bass. 'Rvo high -effi-ciency 15 -inch woofers in a speciallytuned 6 cu. ft. enclosure give solid low -frequency response down to 45 Hz_ Theunit is for use where high-level, low -frequency energy is required. Finish isheavy-duty black carpet; painted or u n-fmished versions are optional. Stand-ard connectors are dual banana andNeutrik NL4MP, and a terminal stripoption can be ordered.Mfr- Renkus-Heinz, Inc.Price- $1700.00


Mfr- Community Light & SoundPrice- starts from $2215.00 (withhorn and driver)

Since echos, delays and other effectsshould be timed, in milli -seconds, tothe beat, the chart is valuable to anyonewho owns a delay, digital reverb, ormulti -effects unit. It can also be used tocompute tempos and the number ofbeats within a fixed time frame, such asa 30 second commercial. The chartgives delay times, in milliseconds, for


tempos from 60 to 250 beats perminute for1/4-, Vs-, and 1/16 -notes, 1/4 -and lit -note triplets and beats per sec-ond. The chart is plastic -coated andmeasures 10x17.Mfr.- J. S. LoBianco EnterprisesPrice- $15.95


-,1-.I

ACOUSTIC TILES

Panorama is one of a series of fiveceiling tile patterns. These SONEXceilings are made of a lightweight,open -celled material. The deep wedgesof the pattern help to deflect and dissi-pate sound energy while directing itinto the open cells of the tile. Then theoffending noise is literally trapped inthe tiles' microscopic pockets. Accord-ing to testing in strict accordance withASTM C 423 -Ma procedures, theweighted noise reduction coefficient(NRC), which measures acoustic per-formance, ranged from 0.75 to 0.85. Bycomparison, most standard acousticalceilings have a NRC range of 0.45 to0.55. Made of an exclusive melamineresin, these ceilings meet all public andcommercial building codes for firesafety. Each lightweight 24 -inch by 24-

inch by 2 -inch tile fits all standard andfine line suspension grids. The soft,flexible design makes it easy to trim orcut.Mfr.- Illbruck

MONITORS

PBM 6.5 and the PBM 8 are twoplayback monitors. At 12 lbs. each (11-1r2x8x8-1/2), the 6.5 is a small, cost-ef-fective, full bandwidth mini monitor.Its rear -firing tuned port produces alow -frequency response down to 57Hz, and allows for an extremely com-pact size. Its 3/4 -inch ferro-fluid-cooled polymide dome tweeter extendstop end high -frequency response tobeyond 20 kHz. The driver accompani-ment is knitted together by means of aprecision hardwired crossover unit,utilizing robust low loss components,and heavy-duty input terminals whichwill accept standard V4 -inch spacedbanana plugs and the majority of high -

quality, specialist audio cables. '11-ans-ducers and crossover assemblies areneatly housed in a high -density, parti-cal wrap cabinet, specially designed tominimize unwanted cabinet reso-nance, and high -frequency reflection.A little larger than the 6.5, at 15x10x10-

0) 1/2, the PBM 8 has a 8 -inch poly conemid bass transducer, utilizing an effi-cient long -throw, high -power voice

0- coil. Low frequencies to 47 Hz are con-< trolled by the rear -tuned port, with2 high frequencies beyond 20 kHz pro-

vided by a 1 -inch ferro fluid cooled pol-ymide dome tweeter.Mfr- Tannoy North America, Inc.

Price- $5.00 or $6.00 per square foot,depending on quantity

Price- $299.00 (PBM 6.5)$448.00 (PBM 8)


Circle 68 on Reader Service Cardco

COMPACT AMPLIFIER

PM -100 is a new single rack -spacemagnetic field power amplifier. Thisversatile power amplifier is designedfor the requirements of broadcast andsound contractor use, as well as thedemands of musical instrument andsound reinforcement applications.Among the unit's many features are ahigh -efficiency linear tracking, fullcomplementary output stage, clippingeliminator circuitry, series/parallelmono capability, barrier strip inputs,front panel metering, and a stereoheadphone jack.Mfr.- Carver CorporationPrice- $629.00


SAMPLED LIBRARY

The EMAX Gold Series Library arespecially prepared library disks providehigh quality audio samples availablefor the EMAX product line. All soundswere originally sampled and processed

MIC SYSTEM

Neumann's microphone series KM100 is a modular condenser micro-phone system with a small diameter(21mm) capsule. The system consistsof an active capsule that connectsdirectly to the output stage forming anaxially addressed microphone 32/3 -in-ches long. The active capsule, which isabout 1.5 -inches long and 0.8 -inches indiameter, can also be connected to theoutput stage via a thin cable up to 150 -feet long. The initial offering includesfour interchangeable capsules: AK 30omni, AK 40 cardioid, AK 45 cardioidwith low -frequency roll -off, and AK 50hypercardioid. A wide variety of acces-sories, including stands, extensiontubes, goosenecks and cable hangersfor mounting the mics and capsules,are immediately available. The fet100's electronic circuitry is similar tothe studio condenser microphone, theNeumann TLM 170. These hybrid,transformerless electronics result in amicrophone which has 4 dB less self -noise, 3 dB higher output level and a 12dB wider dynamic range (124 dB whichis 28 dB greater than a 16 -bit digital re-corder) when compared to the KM83/84/85 series.Mfr- Gothdm Audio CorporationPrice- $600.00 (KM 140)

$725.00 (KM 150)

using the Emulator III's true 16 -bitlinear circuitry and extensive digitalprocessing functions. The sounds werethen digitally transferred directly intothe EMAX to preserve this sonic clar-ity. The result is an improved samplewith increased fidelity and dynamic


range. All Gold Series diskettes areprovided exclusively on professionalquality TDK media.Mfr.- E -mu Systems, Inc.Price- $15.95 per disk


0co

FOR SALE

DAVIDSONELECTRONICS

1 6 - 7

SERVICING:MUSICAL INSTRUMENTS

REINFORCEMENTPRORECORDING

BY APPOINTMENT

5 3

-AUDIO

- 0 1 9 7

ONLY% /41%/2MOMIILUILWWI \ NrfferAgrAYSOMMUIRIMMIONIk NVCrA70.700E/31/1111111111EINEMZPr AIMEEIM ISILIIMILIMIBM WWII MIMI ILI IIII MIWIMBEE11 1111111111W1WAYMEM111111111111illni7,7,:;.: .. IMINNIIIIII.k.,...wW

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McIntosh 2200 power amp w/powerguard. McIntosh C-28 pre -ampw/cabinets-Puff shape-Homestereo application only. Sold as apair. Call for price: 207-474-2357.

FOR SALE: Studer A-80 24 -track.New capstan, pucks, brakes. $22K.Call Clay at 516-759-9110.

MAGNETIC RECORDING HEADSRELAP/REPLACEM ENT for Audio,Video, Time Code, Duplication. 30years of head design experience.IEM, 350 N. Eric Drive, Palatine, IL60067. (312) 358-4622.

EMPLOYMENT

Experienced Manufacturing Mark-eting and Sales executive seeksnew challenges in the ProfessionalAudio Industry. Proven accomplish-ments include: sales level achieve-ments, development of marketingstrategies and materials, Inter-national sales, marketing and dis-tribution, and product dev-elopment. Send inquiries to:Sagamore Publishing Co., Box AB,203 Commack Rd., Suite 1010,Commack, NY 11725.

Quit smoking.WE'RE FIGHTING FOR American Heart

'OUR LIFE Association

Closing date is the firstof the second monthpreceding the date ofissue.

Rates are $1.00 perword with a $25.00minimum. Boxed adsare $40.00 per columninch. db Box Numbersare $8.50 additional forwording "DepartmentXX" plus $1.50additional for postageand handling.

Quantity discounts are:3X -15%; 6X -30%.

ALL CLASSIFIEDSMUST BE PREPAID

Send copy to:

db, The SoundEngineering Magazine,203 Commack Road,Suite 1010, Commack,NY 11725.

Peof,te, Pt4a4... &Htfre4,z4p

BASF Corporation InformationSystems has promoted TerenceO'Kelly to the position of Director ofNational Sales for Audio/Video Pro-fessional Products. Mr. O'Kelly mostrecently held the position of NationalSales Manager for Audio/Video Pro-fessional Products. He is credited withthe development of the BASF 'PapeClinic program for dealers and dupli-cators and has written a series of tech-nical publications dubbed "The Inven-tor's Notebook."

Steven W. Terry has been appointedChief Operating Officer for MediatechWest, the three-year old offshoot ofChicago -based Mediatech, Inc., a com-mercial tape duplication/distributionorganization. Mediatech West has em-barked on a multi -million dollar ex-pansion program to update its current60,000 square -foot facility, and to aug-ment its production capabilities with15,000 square feet of additional space.In his new position, Terry will be re-sponsible for all videotape post -pro-duction operations and implementingthe company's expansion program.

According to M. Hosoda, presidentof Otari Electric Co. Inc., the companyis integrating its offices with easy accessto central Iblcyo. In addition, in April,1989, the company name will change toOtari, Inc. Otari celebrates its 25th an-niversary in April.

John Johnson, President and CEOof DOD Electronics, and three inves-tors, Charles Chewning, Tom Hender-son, and Robert Henderson, have pur-chased DOD Electronics, buying outthe interests of Mr. David 0. Di -Francesco, former partner with Mr.Johnson in the ownership of the com-pany. The change of ownership brings

new financial strength and experienceto the operations of the company.

Orban Associates announced theappointment of David Roudebush tothe position of Marketing and SalesManager for Orban's professional pro-ducts (their Blue Panel line). Roude-bush will be responsible for worldwidemarketing and distribution of Orban'sexisting and upcoming products, ex-cluding the OPTIMOD and broadcasttransmission products which will con-tinue to be managed by Howard Mull-nack

Russell Johnson, chairman andfounder of Artec Consultants Inc., an-nounces the recent addition of VVal-fredo Toscanini to Artec's team ofacoustics and theater design special-ists. Mr. Tbscanini will be working onlong-range planning, feasibility stu-dies, and business development. Afterreceiving a Masters degree in Architec-ture from Yale University, Mr. lbscan-ini did post -graduate work at the Wag-ner Festival at Bayreuth, Germany.Working with Thomas Munter, the in-ternationally respected Germantheater architect, his research involvedthe study of elements of theater designand analysis of traditional and moderntheater architecture. Mr. lbscanini hadrecently co-authored a photo -biogra-phy of his grandfather, Arturo.

Solid State Logic announces the ap-pointment of Colin Pringle as head ofMarketing. He will be based at SSI:sOxford headquarters. He has workedin the UK, USA, and Europe, andbrings with him detailed knowledge ofaudio and broadcast media worldwide.

Denon America, Inc. President, Mr.Takayasu Yoshida, announced the pro-motions of four execu tives to new man-

agement positions in the companywhich is a subsidiary of Nippon Colum-bia, Japan. Robert Heiblim has beenpromoted to Executive Vice President.Akira Saito has been promoted toSenior Vice President. John Langan isnow Vice President. Ken Furst hasbeen promoted to Director of Market-ing, a newly created position which re-flects the expansion of Denon'smarketing activities.

Berldee College's Music Productionand Engineering program asked sounddesignerJay Rose to re -work their Pro-duction for Film and Video course.While some of the course topics arewhat might be expected (editing musicagainst picture, or mixing for stereoTV), others range from productionhouse salaries to client relations. Rosealso includes a generous dose of filmhistory. The course is part of a four-year degree program aimed at bothmusical and technical training as wellas sensitivity to the needs of variousmedia. According to Berklee's Depart-ment Chairman David Moulton, whenthe students leave the school, they willhave been prepared with a full set ofsurvival skills to adapt to a volatile in-dustry.

NewYorkTechnical Support, Ltd. inconjunction with Al Theurer, has re-cently formed a separate installationcompany. Theurer was previously thelead wire person for New York Tech.The new installation company is doingbusiness as New York Tech and is offer-ing s ite planning,computer-aided serv-ices, ergonomic optimization, paneldesign, installation and wiring design,and AutoCad operation. In addition,separate wiring services such as patch -bay assemblies, re -wiring and customharness construction are available.

5.1

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Georg Neumann GmbH is celebrating its 60th year. In honor of the occasion, Gotham Audio Corporation dusted off an oldphotograph. Shown is Georg Neumann, his wife Elie, and Jerry Graham, at the 1967 AES Convention in New York City.Graham, Gotham's Eastern Sales Manager is currently celebrating his 25th year with the company.

We've Moved!

db Magazine and ELAR Publishing can be reached at:

203 Commack Road, Suite 1010

Commack, NY11725

516586-6530

cJCO

SE RAL PORT/MOCEL MTC-1

The or tional MTC-1 plugsinto this MIDI port, youraccess to the world ofMIDI. With a sequencerthat supports our SystemExclusive you'll be able tocontrol all transport func-tions and make the R8operate as a slave in yourMIDI programming.

The First MTRCapable of

MIDIon

M Can stave to MIDI and run automatically.Et Can synchronize to video via SMPTE

Time Code.MrBuilt-in kill function Remote Control.Eif Fully prcgrammable- 10 -position memory.g Under $2900.*

SYNCHRONIZER

The R8 works with all ma-jor synchronization sys-tems, but best of all, usethe R8 with our completeline of generators, proces-sors and controllers - allsoftware based, thereforealways current.

'Actual retail pnces are determined by intividual F,,stex Jeakrs

The enti-e front panel isremovable, so you cancontrol all functions -more than ever before -right from your workingposition. Once you set upyour R8 it acts like anyother computer. Tell itwhat to do, and it does it.Faithfully

Program up to ten memory points and you'll haveAuto Locate, Auto Play,Auto Return, Preroll, andZone Limiting commandsright at your fingertips. Thememory is fully accessibleso you can change cuepoints and functions easily.

R8The 8 -Track Computer with the Built-in Remote.

Fostex©1989 FOSTEX 15431 Blackburn Ave Norwalk, CA 90650 (213) 921-1112


We Dili Just Design ANew MicrophoneWe Changed

The Future Of Sound.

The Beta 58 represents a significant advancein dynamic transducer design and a major break-through in microphone performance. Everymeasurable parameter has been optimized forunprecedented sound quality.

The Beta 58 microphone is the first to com-bine the extra -hot output of Neodymium with atrue supercardioid pattern.

The unique three -stage directional tuningnetwork eliminates the irregular off -axis responsedisplayed by other microphones. The result:greater working flexibility and extraordinarygain -before -feedback. No other dynamic micro-phone has more usable power.

Another new performer is the Beta 57 instru-

ment microphone. The Beta design providesoutstanding isolation from unwanted soundsand freedom from off -axis coloration. All formore impact and separation in the mix.

Hear how a Beta Microphone can change thefuture of your sound. For our new brochure andthe nearest dealer, call 1-800-257-4873. In Illinois,1-800-624-8522. Shure Brothers Inc., 222 HartreyAve., Evanston, IL 60202-3696. The Sound OfThe Professionals® ..Worldwide.

SHURE®New Beta 58"


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