22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 1/18

Postedby: DonSolaris On: March18,2014 2

Category: tips

Synthesizer basics

ThestructureStructureofalmostallsynthesizersisbasicallythesame.Itstartswiththetonegeneratorwhosefunctionistocreatethesound.Onanalogsynthesizers,thisgeneratorisasimpleoscillatorcircuit,whichcangeneratefewbasicwaveformslikepulse,saworsinewave.Thereforeonanalogsynthesizersitismorecommontousetermoscillatorthantonegenerator.Ondigitalsynthsusedtermsare:wavegen,wavegenerator,tonegenerator,andsometimes,evenanoscillator(thoughitisnotarealoscillatorinside).

Nextcomesthefilterwhichdefinesthetimbreofthesoundandadds/removesharmonicsfrom

J?

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 2/18

Nextcomesthefilterwhichdefinesthetimbreofthesoundandadds/removesharmonicsfromtheoriginalsoundcreatedinoscillator.Filterisfollowedbyanamplifier,inwhichyousetupvolumechangeofthesound.EnvelopesandLFOsareusedtomanipulatevarioussettings.Forexample,inoscillatortheycancontrolitspitch.Infiltertheycandefinefilterchangesoverthetime.

Thiswasthebasicdescription,howevereachsynthcanhaveitsownandmorecomplicatedstructure.ImageaboveshowsusthestructureofRolandsXVsynthesizer.Eachpatchcancontainuptofourtoneseachwithitsownsettings(sounds).Patchalsocontainscommondata,whichconsistsofparametersthatapplytoallfourtoneslike:patchname,overalllevel,octaveshift,keymode(mono/poly),portamentosettings,benderrangeandmore.Patchalsocontainsmodulationcontrol(matrixcontrol)inwhichyouspecifywhichcontrollerwillchangewhich

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 3/18

modulationcontrol(matrixcontrol)inwhichyouspecifywhichcontrollerwillchangewhichparameterforexamplemodwheelonthekeyboardtochangeamountofcutoffandresonanceofthefilterorthepitchofthewavegenerator(WG).

OscillatorThepurposeofoscillatoristoproduceasoundthatyouwilllaterprocesswithafilterandamp.Onceyoupressthekeyonthekeyboard,youactivatetheoscillator(inanaloguesynthesizeritisactuallyalwayson).Oscillator(OSC)isthestartingpointofanysynthesizer.Itisaplacewherethewaveformisbeingcreated.Inanalogsynthesizer,oscilatorcanbedigitally(DCO)orvoltagecontrolled(VCO)anditusuallyproducespulseorsawwaveofwhichpulseswidthcanbecontrolledandevenmodulated(PWM).Alloscillators,nomatterforwhatapplication,workinthesameway.Ifwelookattheirheartwillfinditlookssomethinglikethis.

Tobedescribedinthesimplestway,oscillatorisanamplifierandafilterthatoperateinaloop.ThebasisofoperationisthetunedresonantcircuitforexampleLCcircuitthatismadeofinductor(L)andcapacitor(C).Inthiscircuitvoltageandcurrentvarysinusoidallywithtimeandare90degreeoutofphase.Thereareinstantswhenthecurrentiszero,sotheenergystoredininductoriszero,butatthesametimethevoltageacrossthecapacitorisatitspeak,whileallofthecircuitsenergyisstoredintheelectricfieldbetweencapacitorsplates.Therearealsoinstantswhenthevoltageiszeroandthecurrentisatapeak,withnoenergyinthecapacitor.Then,allofthecircuitsenergyisstoredintheinductorsmagneticfield.Asyoucansee,theenergystoredinthiselectricalsystemisswingingbetweentwoforms.Unfortunatelythisswingingwontgoforeverduetocircuitlosses.Conductorshavesomeresistance,aswellascapacitorandinductor.Thatisthereasonwhyweneedamplification.Thegoalofthisamplificationisnottoaddsomehighgain,butjusttocompensatethelosseswehaveinLCcircuit.Youcanimagineoscillatorlikependulum,whichduetodragandfrictionlooseitsmovementenergy,soyouneedtokickitfromtimetotime.

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 4/18

Attheoutputofoscillatorwecanhavevariouswaveforms,dependingonthetypeofoscillatorthatwebuilt.Forexampleifouroscillatorisproducingasinusoidalwave,wecallit:sinewaveoscillator.Therearemanytypesofoscillators,mostknownareshownonimageabove,andthoseare(fromlefttoright):sine,triangle,squareandsaw.Squareisactuallyapulsewave,with50%width.

WavegeneratorDigitalsynthesizershaveadifferentkindofoscillatorintheirheart.Itisnotaclassicoscillatorthatwejustdescribed,butadevicethatusesPCMwaveforms.Pulsecodemodulation(PCM)isadigitalrepresentationofananalogsignalwherethemagnitudeofthesignalissampledregularlyatuniformintervals,thenquantizedtoaseriesofsymbolsinabinarycode.Ifyouhavesomewavfilesonyourcomputer,thosearethePCMwaveforms,thesamethatareinyourdigitalsynthesizer.Advantageofdigitalwavegeneratoristhatitisnotlimitedtobasicwaveforms(sine,saw,square,etc.)butcancontainanykindofdatathatwaspreviouslydigitized.Youcanhaverealpianosamples,guitars,drums,etc.Ofcourseifyouwantyoucanhavebasicwaveformstoo.Mostdigitalsynthshaveatleastasineandasawwavesampleinsidetheirwaveformmemorysoyoucancreatesomeanalogsoundingtonestoo.

Nowyoumightask,whyoneneedsanalogsynth,whenthesametypeofwavescanbecreatedwithdigitalPCMwavegenerator.Theanswerwasactuallyjustsaidisintheprevioussentience,itisawordPCMgenerator.Eachtimeyoutriggerthistypeofgenerator,itwillproduceexactlythesamesoundingwaveform.Resultisuniformtonethatstaysthesame.Incontrast,analogsynthesizershaveimperfectoscillators,whichresultinvarioustypesoffluctuationsthataredifferenteverytimeyouhitthekey.Inasensetheysoundunpredictedanddifferentoneachotherkey.Butthatisjustthebeginningofthestory.Onceyouengagepulsewidthmodulation,thereisnodigitalPCMsynththatcanenterthisarea.Thencomestheanalogfilter,whichagainaddsitsowncharacter.Inshort,thisisoneofthereasonwhy30yearoldsynthesizersusuallycostmorethanthelateststateoftheartPCMdigitalsynthesizerwith9000patches.

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 5/18

Itisimportanttounderstandthatwetalkabouttwodifferentworldshere.Itwouldbeprettynaivetoblamesomedigitalsynthandcallitpoorbecauseitcantdosomegoodanalogsounds.IfsomeoneaskswhyaPCMsynthcantmakeasuperthunderingMoogbasssound,thesimplestanswerisitwasneverdesignedtoso.

FilterThemostdramaticchangeofyoursoundistakingplaceinthefiltercircuit.Therichertheharmoniccontentonthewaveform,themorethechange.Exampleofrichharmonicwaveformswouldbesquareandsawwave.Ifyoursynthesizerdoesnothappentohaveresonantfilter,youareactuallymissingonereallyimportantandcharmingaspectofasynthesizer.

Ifwelookatfrequencydomainofasound,forexamplesquarewavewhichisrichinharmonicsandplayalownoteatsay20Hz,wecanseethattheseharmoniccomponentsarespreadinthewholeaudiorange(20Hzto20kHz).Whatfilterwilldoistoisolatesomepartsofthisrangeinordertoaccentuateitsotherfrequencies.

TypesoffiltersThemostknowfilteristhelowpassfilterLPF.Itreducesthevolumeofallfrequenciesabovethecutofffrequency.Youcanspecifythiscutofffrequencyinfiltersettings.Onceyoucutouthighfrequencyrange,thesoundwillbecomemoremellow.

NexttypeoffilterwidelyknownisahighpassfilterHPF.ItisdoingexactlyoppositethingfromLPF.Itcutsthepartofthespectrumwhichisbelowthecutofffrequency.Itcanbeusefulforpercussivesounds(niceanalogsoundinghihatscanbemadewithit).Highpassfiltercanberesonanttoo,butactuallytherearenotsomanysynthesizersthatfeatureit.KorgMS20oneof

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 6/18

resonanttoo,butactuallytherearenotsomanysynthesizersthatfeatureit.KorgMS20oneoftherareanaloguesynthsthatfeaturesanalogresonanthighpassfilter.

AnoneofthemostspecificsoundingfiltersisprobablythebandpassfilterBPF.Thisfilterleavesonlytheregioninthevicinityofthecutofffrequency,andcutstherest.Withresonancesettingyouareactuallyshapingthewidthofthisfilter.Themoreresonance,themorenarrowthisfilterwillbe.Imagebelowshowsfrequencyresponseofthreebasicfiltertypeswejustdescribed.

ResonanceOnceyouactivateresonanceonalowpassfilter,newharmonicswillpopupinthelowerrange,creatingnewsoniccomponentsthatdidntexistinoriginalsound.Highlevelsofresonancecanproduceselfoscillation.RolandsJunomanualhasaveryinterestingandspecificexplanationofresonance(ifinditreallyfuntoreadittoday,butactuallyitisagoodexplanation):Thiscontrolemphasizesthecutoffpointsetbycutofffrequencyknob.Asyouraisetheknob,

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 7/18

Thiscontrolemphasizesthecutoffpointsetbycutofffrequencyknob.Asyouraisetheknob,certainharmonicsareemphasizedandthecreatedsoundwillbecomemoreunusual,moreelectronicinthenature.Ifyoualterthecutofffrequencywhiletheresonanceknobissettoahighlevel,youcancreateatypeofsoundthatisattainableonlyfromasynthesizer.RolandJuno106Manual

Filterpoles/slopesSometimesyouwillreadthatafilteris4poletype.Thisisjustanothertermfor24dBfilterslope,whichisthemostcommonfiltertypeintheworldofanaloguesynthesizers.Numberofpolesdefinesthesharpnessofthefilter.Themorepolesfilterhas,thesharperitsfrequencyresponsewillbe.Thisalsoaffectstheresonance,sincesharperfilterresultsinmorepowerfulsoundingresonance.RolandTB303usesthenotsocommon,18dBfilterslope.Nowyoumightwonder,whatthis18dBmeansanyway.Itisaunitwhichtellsyouhowmuchafilterwillblockperoctave.Whichinthiscaseis18dB.Ifyouputafiltercutoffpointto440Hz,oneoctaveaboveat880Hzsignalwillbeattenuatedfor18dB(whichisabout63times).

Ifafilteris4pole,thesignalwillbeattenuated24dB,whichfor440Hzcutoffpointmeansthatthesignalon880Hzwillbeabout255timesweaker.Imageaboveshowsattenuationcurvesoffourfiltertypes:6dB,12dB,18dBand24dB.

Whichfiltershouldyouuse?Thechoiceisuptoyou.Ifyouprefernicesmoothfiltersweepsounds,youshoulduse12dBfilterwithagoodresonancevalue.Forthunderingbasssoundsorhighresonancezapsyoushoulduse24dBfilter(fullresonanceforzaps).While6dBfilterisgenerallynotused,itcomeshandforsampleplayback,togentlyremovehighendfromtheharshsoundingsamples,whilenottotallydistortingthephaseofthesample.

AmplifierandenvelopeLaststageofsoundmanipulationthatistakingplaceinthesynthesizerishappeningattheamplifiersection.Itspurposeistocontrolvolumechangesofthesound.OnanalogsynthesizersamplifierisusuallycalledVCA(ifitisvoltagecontrolled)orDCA(ifitisdigitallycontrolled).On

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 8/18

amplifierisusuallycalledVCA(ifitisvoltagecontrolled)orDCA(ifitisdigitallycontrolled).OndigitalsynthesizersamplifierisusuallycalledAMPorincaseofRolanditiscalledTVA,whichstandsfortimevariantamplifier.MainpartoftheamplifieristheADSRenvelope.

ADSRenvelopeThisstandsfor:Attack,Decay,Sustain,Releaseanditrepresentsfourpoints.Onceyouhitthekey,youareattheattackpoint.WithAttackyouaresettingamountoftimethatitwilltakeforsoundtoevolvefromitsstartinglevel,tothepointwhereyoupressthekey.ThisisfollowedbyDecayinwhichsoundcanevolvetoanotherlevelthatyouset.ThisisfollowedbySustainpoint.Aslongasyouareholdingthekeypressed,youareatsustainpoint,andthelevelyousetatsustainpointwillbethelevelofthesoundduringthetimethekeyisheld.Onceyoureleasethekey,thesoundwillgooff.TopreventthesoundfromgoingawaytosoonyoucansettheReleasepoint.Releasesetstheamountoftimeitwilltakeforsoundtogettozerolevel,afteryoureleasedthekey.

Thereareenvelopeswithmorethanfourpointsthatwedescribed,buttheyallworkinthesameway.Rolandstypicalenvelopeconsistsoftwodecaylevels.SomeYamahasSYseriessynthssuchasSY77andSY99havelooppointsthatyoucansettotheenvelopewhichisprettycoolfeature.

LFOandcontrolThepurposeofLFOistoaltervarioussoundsettingsinback/forthcyclicmanner.UsuallyLFOcanapplychangetooscillatorspitch,filtercutofffrequencyandamplevel.IfyouapplyLFOtothepitch,youwillgetvibrato,ifyouapplyittofilter,yougetsweepingsound(suchaswahwah),ifyouapplyittoamplevel,yougettremolo.

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 9/18

Asitsnameimplies,LFOisanLowFrequencyOscillator.Usuallyitconsistsofafewbasicoscillatorwavetypeslikesine,saworsquare.YoucanimagineLFOlikeahelpingdevice,whichishelpinginwaythatyoudonthavetomanuallychangethepitchorlevelofthesound.InsteadyouprogramLFOtodothat.Howeverifyoudowishtochangesomesettingmanually,thenyouneedtospecifythemincontrollersection.

Audioexample1:Toneslevelmodulation.Clickheretohearoriginalnonmodulatedsound.LFOwassettomodulateamplifier(tonelevel).LFOswaveformwassinewave.Resultcanbeheardhere.

Thetwoimagesaboveshowamplitudeasafunctionoftime(waveformdisplay).Asyoucanseeoriginalsoundhadconstantlevel(amplitude).OnceweappliedLFO,levelstartedtomodulatefromminimumtomaximumvalue.Shapeofthesinewavethatwasmodulatingoriginaltonecanbeclearlyseenonsecondimage.

Audioexample2:Tonesfrequencymodulation.Clickheretohearoriginalnonmodulated

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 10/18

Audioexample2:Tonesfrequencymodulation.Clickheretohearoriginalnonmodulatedsound.LFOwassettomodulateoscillatorspitch(frequency).LFOswaveformwassinewave.Resultcanbeheardhere.

Imageaboveshowsfrequencyasafunctionoftime(spectraldisplay).ItcanbeclearlyseenhowappliedLFOmodulatesthepitch(frequency)oftheoscillator.Shapeofthesinewavethatwasmodulatingoriginaltonecanbeclearlyseen.Originaltonewasfixedfrequencyat440Hz.OnceweappliedtheLFO,tonestartedtovarythepitchforabout50Hzaboveand50Hzbeloworiginalfrequency.

ControlMostofdigitalsynthsofferyoutoapplyvariouscontrollerslikemodwheel,aftertouchorvelocitytosomeofthesoundsparameterslikefilterscutoffpointorresonance,soundlevel,etc.Somesynthscallthisfeaturemodulationmatrix.Itgoessomethinglikethis.Firstyouspecifythesourceofthecontrollerforexamplemodulationwheelonthekeyboard.Thenyouspecifyitsdestination,forexamplefiltercutofffrequency.Nowyousettheamount,andyouarereadytomodulatethefilterwithmodulationwheel.Iffiltersettingsonthesoundareonthemaximumopenposition,thenyouneedtoapplynegativevaluetothecontroller,sothatwhenyoustarttomovethewheel,filtergetsclosed,fortheamountyouspecified.SomebettermodulationmatrixsystemswillallowyoutoapplyalmostanysynthfeatureasasourcetomodulateitsdestinationforexampleLFO1tomodulatespeedofLFO2whichcanresultinverycomplexandunpredictedresults(thisisincasethesynthhastwoLFOs).Thisistheareathatrequiresalotofexperimenting,butresultsarealwaysrewarding.

Abbreviationsandcommonterms

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 11/18

Circuitbendingischanging,removingoraddingnewelectroniccomponentswithinsynthesizertoachievedifferentperformancethatisunavailableinoriginalversion.Usuallycheapsynthsarebeingcircuitbenttosoundmorewild,unpredicted,strange,oralltogether.Circuitbendingresultswithwarrantyvoid,andcandamageyoursynthpermanently.

Legatoisafunctionthatshouldonlyworkinmonophonicmode.WhenLegatoison,pressingonekeywhenanotherisalreadypressedcausesthecurrentlyplayingnotespitchtochangetothatofthenewlypressedkeywhilecontinuingtosound.Thiscanbeeffectivewhenyouwishtosimulateperformancetechniquessuchasaguitaristshammeringonandpullingoffstrings.

Modulationwheelaffectsthesoundasspecifiedbythecontrolparameters(controlmatrix).Onmanysynthsitissettovibratobydefault.

Portamentoisafunctionthatcausesthesoundspitchtochangesmoothlyfromonenotetothenextnoteplayed.Portamentoiscommononguitar,violinandotherstringinstruments.However,portamentoisnotpossibleonafixedpitchinstrumentlikethepiano.Onasynthesizer,parametercalledportamentotimeorportamentospeeddefinesthespeedatwhichanoscillatormovestoanewnoteyoupressedonthekeyboard.WhentheKeyAssignModeis

mono,thiscanbeeffectiveinsimulatingperformancetechniquessuchasaviolinistsglissando.

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 12/18

Next PostSynthesistypes

Reply

mono,thiscanbeeffectiveinsimulatingperformancetechniquessuchasaviolinistsglissando.

Pitchbender(pitchwheel)bendspitchoftheplayednoteupordown,andisspringloadedtoreturntocenterposition.

Comments (2)

Great DepressionOctober18,2014at23:21

Goodblogyouhavehere..Itshardtofindqualitywritinglikeyoursthesedays.Ireallyapppreciateindividulslikeyou!

Takecare!!

Don SolarisDecember2,2014at21:09

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 13/18

Reply

Name(required)

Email(required)

Website

Post Comment

Thanks.Ilikesynthsandsharinginfos.

Leave a ReplyYouremailaddresswillnotbepublished.Requiredfieldsaremarked*

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 14/18

F?ttstt

GO

Store

RolandJV1080PatchesSoundset

RolandJD990PatchesSoundset

RolandMC909SamplePack

YamahaAN1xPatchesSoundset

NordWaveVintageDigitals

CasioCZ1PatchesSoundset

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 15/18

Free Samples and Patches

CasioCZ230soundsetforCZ1

KorgX5DDrums(samples)

NordWaveDrumset(samples)

RolandTR606(samples)

Tech Articles & Reviews

RolandJD990revolutionaryconcepttwodecadeslater

SCSItoCFBlackboxinterfaceforsamplers

EnsoniqTS10wavetableandwavesequencingmonster

MoogVoyagerO.S.Mods(PWM,filterpoles)

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 16/18

RolandLCD1sampleCDfinallyavailableonS550!

YamahaA4000/A5000Review

Whyusingoldhardwaresamplers?

HowtouploadSYXfilestosynthesizerviaMIDIorUSB

KorgTridentMkIDemo

WaldorfStreichfettDemo(makingof)

TheultimateRolandJV,JD,XVF.A.Q.

DynacordDRP20review

ASR10synthesizingindustrialsounds

ASR10synthesizinganorgan

EventideH3000asaformantsynth

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 17/18

F?ttstt

AndromedaA6soundimprovement

DeepFMbassonRolandJD/JV/XVseries

HowtoachievePWMonRolandsSuperJV/XPandXVseries

RolandJDemulationonSuperJVandXVsynthesizers

RolandJD990ResourceCentre

RolandJD800ResourceCentre

Synthesistypes

Synthesizerbasics

22/2/2016 Synthesizer basics | donsolaris.com

http://www.donsolaris.com/?p=493 18/18

GO

Allrightsreserved.

AllcontentcopyrightbyDonSolarisunlessotherwisenoted.