Cca & More Rmaf

7/30/2019 Cca & More Rmaf

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www.tubecad.com/2010/11/blog0194.htm[2013/6/14 10:31:33]

< Back John Broskie's Guide to Tube Circuit Analysis & Design Next >

30 Nov 2010

Cathode-Coupled Amplifier(+ Aikido CF)

Cathode-Coupled Amplifier (CCA)have covered this circuit many, many times before. Background Blogs:

Kit User Guide PDFsClick image to download
http://www.tubecad.com/2010/12/blog0195.htmhttp://www.tubecad.com/index.htmhttp://www.tubecad.com/2010/10/blog0193.htmhttp://tubecad.com/Product_PDFs/Aikido%20LV.pdfhttp://tubecad.com/Product_PDFs/9-Pin_CCA.pdfhttp://www.tubecad.com/2010/10/blog0193.htmhttp://www.tubecad.com/index.htmhttp://www.tubecad.com/2010/12/blog0195.htm


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2005/April/blog 422007/05/blog 1052007/05/blog 1062007/05/blog 1072007/05/blog 1082008/11/blog0152

The last entry is actually a good place to start, as it shows several ways to overcome theroblem of dissimilar cathode-to-plate voltages in a CCA. This problem is the CCA'sne big hassle to overcome. In fact, if the using CCA circuit didn't entail dealing with

dissimilar cathode-to-plate voltages, I am sure that this topology would be much moreopular, as it has much to offer, such as low input capacitance and no phase inversionnd a high-impedance feedback port.

n the schematic above, on the left, we see two triodes that share a common cathodeesistor and separate B+ voltages, but the same DC grid voltage (0V). If we wish to usesingle B+ voltage, then we must alter the cathode-to-grid voltages to compensate for

he dissimilar cathode-to-plate voltages, as shown in the schematic on the right.

Actually, the unspoken assumption here is that the two triodes share the same currentdraw. In fact, this is a precondition worth retaining, as the identical idle current helpsinearize the two tube's gain. If we are, however, willing to run different idle current

draws, then we can use the same grid-bias voltage for both triodes. An inspection of ariode's plate curves shows how this can be done.
http://tubecad.com/2005/April/blog0042.htmhttp://tubecad.com/2007/05/blog0105.htmhttp://tubecad.com/2007/05/blog0106.htmhttp://tubecad.com/2007/05/blog0107.htmhttp://www.tubecad.com/2008/11/blog0152.htmhttp://www.tubecad.com/2008/11/blog0152.htmhttp://tubecad.com/Product_PDFs/CCDA%20Octal.pdfhttp://tubecad.com/Product_PDFs/ACF%209-Pin.pdfhttp://tubecad.com/Product_PDFs/BCF%209-Pin.pdfhttp://www.tubecad.com/2008/11/blog0152.htmhttp://www.tubecad.com/2008/11/blog0152.htmhttp://tubecad.com/2007/05/blog0107.htmhttp://tubecad.com/2007/05/blog0106.htmhttp://tubecad.com/2007/05/blog0105.htmhttp://tubecad.com/2005/April/blog0042.htm


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Note the -2V grid line and where it intercepts the 100V and 150V plate voltages; with00V on the plate of this triode, the conduction equals 3mA; with 150V, 7.6mA. Yet,oth plate voltages rely on the same -2V of grid voltage. Applying these twoperational points in one circuit is straightforward enough: just add the 3mA and.6mA together to find the correct common-cathode resistor value and use just themA idle current amount for determining the plate resistor value.

The downside to this technique is an increased distortion figure. Furthermore, theight triode will be expected to drive the external load resistance and capacitance, butts idle current is less than half the left triode's current conduction, unfortunately. (Onhe other hand, if the right triode is only expected to drive a cathode follower's grid,hen the weaker current is much less of an issue.)

f we wish to keep the equal idle currents and the single B+ voltage, then we will haveo give the triodes differing grid-bias voltages. Once again, an inspection of the plateurves shows how this is done.
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This time we hold the plate current steady (for both triodes), which the single greenhorizontal line indicates. At 5.2mA, the green intersects the two plate voltages used inollowing cathode-coupled amplifier design example; namely, 150V and 300V. The gridoltage intercepts occur at -3V and -9.5V, as marked by the red grid-voltage lines. Inther words, the left triode will see a 300V differential and will need to see a gridoltage of -9.5V to draw an idle current of 5.2mA, while the right triode will experience

nly a 150V differential and will need to see a grid voltage of only -3V to draw an idleurrent of 5.2mA.

Okay, I know many are scratching their heads right now, as the right triode is seeing a+6.5V grid bias voltage, not -3V, as the graph's inspection implied. Remember, theathode-coupled amplifier's triode share a common cathode connection, so theommon cathode voltage becomes our reference. Relative to the +9.5V cathode voltage,
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he left triode's grid is at -9.5V and the right triode's grid is at -3V, as +6.5V minus+9.5V equals -3V. Now that everyone is on the same page, the next question is: Whathappened to the negative power supply rail?

A negative power supply could be used, but many tube fanciers just don't do negative

ower supplies and the relatively high common cathode voltage (+9.5V) means that, inline-stage amplifier, more than enough input voltage headroom exists, as line-levelnput signals seldom exceed 2Vpk. Okay, but where do we get a 10.2mA constant-urrent source? We could build one out of discrete solid-state devices, such as a FETnd a source resistor; or we could use a constant-current source IC, such as the LM334r the new Linear Technology LT3092 constant-current source.

The LT3092 is an extremely interesting constant-current source that only requires twoesistors to set its idle current. Because the two resistors tie together at one end, the

LT3092 is considered a two-terminal constant-current source, which can be floated orround or B+ referenced. It can withstand up 40V and source up to 200mA. I haven'tctually had any hands on experience with the LT3092 yet, but I am eager to try someests on it.

On the other hand, because the common cathode voltage is so high, we can get awaywith using a 913-ohm common cathode resistor, as 9.5V / 10.4mA = 913 ohms, whichwill make the solid-state-fearing types happy. The last unanswered question is: Howdo we establish the +6.5V bias voltage for the right triode's grid? Ah, finally we arrive

t the meaty bits. We could use a two-resistor voltage divider that spans from ground
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o the B+ connection. While this would work well enough, this arrangement is notptimal. A better setup is to terminate the voltage divider's top resistor into the rightriode's plate, rather than the B+ connection.

Why is this arrangement better? If nothing else, we will not have to deal with power-upply noise leaking into the cathode-coupled amplifier's output, as the Aikido cathodeollower's output should be dead quiet. Moreover, in this setup, the voltage-divideresistors constitute a DC feedback mechanism that works to keep the correct biasoltage needed to establish a plate voltage equal to half the B+ voltage on the rightriode's plate. Why is this important?

The cathode-coupled amplifier, however, needs a bit more help to make a first-rateine-stage amplifier, as its output impedance is too high and PSRR is weak (almost

nonexistent). Adding an Aikido cathode follower to the CCA input stage makes aomplete, high-quality line-stage amplifier that offers low distortion, low outputmpedance, wide bandwidth, no phase inversion, and a stellar PSRR figure.

E-mail from GlassWare Custom

Hi J ohn,

I received the Aikido PCB today -

thank you for the first rate shippingspeed.

Wanted to let you know that this

is simply the best PCB I have had

in my hands, bar none. The quality

is fabulous, and your

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you do this because you love

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Looking forward to building the

Aikido, will send some comments

when I'm done!
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The Aikido cathode follower DC couples with the CCA stage, and the two-resistoroltage divider defined by resistors R5 & R6 provides the DC feedback loop to keep the

Aikido cathode follower output centered at half the B+ voltage. The second voltagedivider resistor string, R11 & R22, injects the required sampling of power-supply noisento the Aikido cathode follower's bottom triode's grid to null the power-supply noiset the Aikido cathode follower's output. The diode D11 is a safety device that protectshe Aikido cathode follower top triode at start up, when the tubes are cold and notonducting; once the tubes are hot, the diode falls out of the circuit, as it will no longere forward biased.

The LM334 constant-current source is optional, as resistor R3 can be used by itselfthe LT3092 cannot be used on the CCA PCB). On the other hand, the LM334onstant-current source does reduce the distortion substantially (-20dB improvement),ut it does make the CCA a more sensitive to changes in the B+ voltage and willequire more circuitry tweaking to obtain as low a noise figure as the common-cathodeesistor achieves, such as lowering reisitor R9's value a tad relative to R8, say 270hms to 300 ohms. On the other hand, the current source does produce more voltageain from the CCA, about +3dB more with a 12AU7.

Finding the right values for resistors R5 & R6 is easy enough. As we all know, ariode's amplification factor is simply a measure of the relative effectiveness of the gridver the plate in controlling the current flow through the triode. Thus, a triode with a

mu of 10 holds a grid that is 10 times more efficient than its plate. So an increase inlate voltage of 10 volts can be countered by a decrease of 1V on the grid. In other

words, we can maintain a fixed idle current in spite of a 10V increase in plate voltagey moving the grid 1V more negative.

f we inspect the plate curves from the previous examples, we will find the triode's muqual to about 23.1. If we then divide the 150V difference in plate voltages by 23.1, we

et 6.49V, which is close to the 6.5V difference in grid voltages (9.5V and 3V) that weleaned from plate curves. Thus, we need a voltage that yield a 1/mu voltage division;o R6 should be (mu 1) times bigger than R5. This wonderful trick works because theoltage from ground to the Aikido cathode follower's out is equal to the voltage acrosshe plate resistor, R4, which is also the difference in plate voltages.

Finding R11's value takes a bit more work, as the old Aikido formula does not applyhere. If a constant-current source is used to load the common cathodes, then theathode-coupled amplifier offers almost zero power supply rejection, so all of theower-supply noise must be fed to the Aikido cathode follower's bottom triode's grid.

Thus, if the LM334 CCS is used in place of the simple common-cathode resistor, R3,hen the CCA's plate resistor's value must equal B+/Iccs and R11 must be replaced by aumper wire and R8's value must be slightly greater than R9's value to null the power-

Thank you, regards

Gary

Mr Broskie,

I bought an Aikido stereo linestage

kit from you some days ago, and I

received it just this Monday. I have

a few things to say about it. Firstly,

I'm extremely impressed at the

quality of what I've been sent. In

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lightning-quick. J ust more

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wish everyone did business like

you.

Sean H.

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upply noise from the CCA's output. How much greater? It depends on the triode's mund rp. The following formula establishes the correct ratio between resistors R8 & R9,

when a constant-current source is used.

With a common-cathode resistor and 6CG7s, in contrast, there is a 17% reduction in

ower-supply noise at the cathode-coupled amplifier's output. I used the followingalues in my own CCA setup (all tubes are 6CG7s):

f a 12AU7 is used as the input tube, use a 931-ohm common-cathode resistor and setR11 to 15k and R6 to 175k. Wait a minute! Don't you first need to know what the B+

oltage is? No. That's the amazing thing about this topologythese values workerfectly with a B+ voltage that spans 100V to 400V. On the other hand, if a CCS is

used in place of the common-cathode resistor, then the CCA's plate resistor's valuemust equal B+/Iccs. While testing my CCA prototype, I was thrilled to see the outputtage always center to within 1V of the half-the-B+ target, as spun the variac's ACutput voltage up and down.

The PSRR figure, even without the LM334 CCS, was stellar and distortion quite low,bout 0.1% with 1Vpk at 1kHz into a 47k load. I wondered if the DC feedback loop was

not also contributing AC feedback, so I tried the line-stage amplifier with resistor R5ypassed, so the small AC signal present would be shorted to ground. The results were

nteresting; with the bypass capacitor in place, the distortion almost imperceptiblyudged upwards. in other words, very little negative feedback obtains. This makesense, as the line-stage amplifier's open loop gain would have to be greater than thenput triode's mu for negative feedback to take hold. With the 6CG7s, the AC gain is

nly 5.2 (or +14dB).

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Relatively Low-Voltage CCA Line Amplifier

The input triode in the CCA sees the biggest cathode-to-plate voltage differential, soare should be taken to not to exceed the triode's maximum cathode-to-plate voltage.This brings up the controversial issue of the 6DJ8's actual cathode-to-plate voltageimit. Most tube manuals state that the limit is 130Vdc, an amazingly low voltage for ariode. I believe this voltage only refers to the tube under cascode use, not in arounded-cathode amplifier or cathode follower. For example, the JJ E88CCpecifications sheet states that its maximum plate voltage is 220Vdc:

E88CC R. F. DOUBLE TRIODEBase: NOVAL

Uf = 6,3 V

If = 365 mA

Typical characteristic:Ua = 90 V

Ug = -1,3 V

Ia = 15 mA

S = 12,5 mA/V

Ri = 2,6 kO

= 33

Limiting values:Ua0 = 550 V

Ua(la=0) = 400 V

Ua = 220 V

Ua(War


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ower transformer, which rectified up to about 165Vdc, which was then dropped to50Vdc through resistors R12 and R17.) Nothing exploded or arced. Furthermore, theound was surprisingly fine and the gain was close to +20dB. The lower B+ voltagellowed me to use much larger-valued capacitors in the high-voltage power supply220F/200V rather than 47F/450V for C7 & C8 and 270F/200V rather than50F/400V for C5), which greatly reduced the ripple the Aikido cathode follower hado wisk away. In other words, it was dead quiet. I used the following resistor values:

LM334 constant-current sourceThe National Semiconductor LM334 is a well established device. It can be bought inour different packages, but the CCA PCB is configured for the TO-92, three-leadackage.

Specifications

V+ to V- Forward Voltage

LM134/LM234/LM334 40V

LM234-3/LM234-6 30V

V+ to V- Reverse Voltage 20V

R Pin to V- Voltage 5V

Set Current (max) 10mA

Power Dissipation 400mW

ESD Susceptibility 2000V

Operating Temperature Range
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LM134 -55C to +125C

LM234/LM234-3/LM234-6 -25C to +100C

LM334 0C to +70C

Soldering Information

TO-92 Package (10 sec.) 260C

The LM334 requires only one resistor, Rset, to establish its idle current.

The following graph shows the turn-on voltages and bias currents set by various Rsetesistor values.

Note that 10mA, the optimal value for most CCA setups, does not receive a resistoralue, but we can readily see that 6.8 ohms is the correct value. (The LM334 datasheetoes into much more detail, but for tube work, 6.8 ohms is close enough.) Although0mA is the LM334's maximum current flow, the device sees less than 10V with mostubes, such as the 6CG7 and 12AU7, so the device's dissipation is usually less than00mW, well below its 400mW limit. Nonetheless, it is a good idea to attach a small

heatsink to the IC, as it better ensures an accurate idle current.

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The CCA Power SuppliesThe CCA PCB is an All-in-One affair, wherein the audio and power-supply circuitryeside on the one board. The B+ power supply is a simple design that uses cascading piilters to reduce ripple and rectification nastiness.

THe CCA PCB can accept either a center-tapped or non-center-tapped high-voltageower transformer. (In my own CCA setup, I used a 240Vac non-center-tapped

Hammond power transformer.)

The CCA PCB holds the heater power supply as well and it is regulated.


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As can be seen, the power supply can accept either full-wave bridge rectifier circuit or aull-wave voltage doubler rectifier configuration. When used as a full-wave bridgeectifier circuit, the two power supply filtering capacitors are placed in parallel byrienting their positive leads to where the heatsink sits; and the secondary attaches tohe two encircled AC pads.

Configured as a voltage doubler, these capacitors placed in series by being rotated 90degrees clockwise, so the positive leads point to the center-tap (CT) pad at the bottom

f the PCB; the transformer secondary attaches to both the single AC pad in betweenapacitors C13 and C14 and AC pad that feeds rectifier D10 and D8; and D7, D9, C9,

C11 are left off the PCB. If used as a full-wave center-tap circuit, the two heaterapacitors, C13 & C14, are placed in parallel by orienting their positive leads to where

he heatsink sits; and the secondary attaches to the two encircled AC pads while theecondary center-tap attaches to the CT pad.

used a 12Vac/3A transformer, as I like being able to switch the heater power supplyn independently from the B+ power supply. By the way, the CCA can easily be built

upside down, wherein the tube sockets are soldered to the top of the PCB, butverything else attaches to the PCB's bottom. Why? This allows the tubes to protrudehrough holes in the top of the chassis. The usual roadblock is the heater voltageegulator, but on the CCA PCB, I placed redundant solder pads on the bottom for the

LD1085.

The heater regulator uses the LD1085 low-dropout, adjustable, three-pin, 3A voltageegulator. The regulator can be set to an output voltage between 6V to 25V, but thessumption is that a 12Vdc output voltage will be used for the heaters, so that 6.3V

heater tubes (like the 6FQ7 and 6DJ8) or 12.6V tubes (like the 12AU7 or 12BH7) cane used.

Both voltage types can be used exclusively, or simultaneously; for example a 6GC7 for


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he input tube and an ECC99 for the output tube. Thus, if the input tubes (V1 and V2)re 6CG7s and the output tubes (V3 and V4) are 12BH7s and the heater regulatorutput voltage is 12Vdc, then use jumpers J2, J4, and J6.

More RMAF DetailsLast time, I mentioned several of the loudspeakers that I liked at the Rocky MountainAudio Festival, which prompted a friend to ask why I didn't mention any new tube

ear. Well, I did see and hear some interesting tube amplifiers. But first let me

describe what happened when I first arrived at the show. I walked into a room filledwith $200,000 worth of audio gear and I listened to an excellent solid-state powermp through some excellent speakers that cost twice as much as my minivan. How didt sound? Marvelous. So much so that I began to worry about tubes having a harderime competing with so strong a contender.

magine a wife or a girlfriend being dragged into a car part store by her significantther. Her expectations of having a good time are low, so she is startled see an

mpossibly handsome man standing behind the counter. "Maybe I should shop heremore often," she says to herself. Upon approaching the counter, she is disappointed toee that the gorgeous face was only printed on a life-sized poster cutout of a famousace car driver and that the actual living fellow behind the counter was only okayooking, with a bad haircut and in need of a shave. Well, this is how I felt, for as prettys the picture the solid-state amplifier painted was it never felt real. And even whenhe tube power amplifier rendered a tarnished sonic picture, zits and pockmarksncluded, the sound still maintained a believability about it. In a nutshell, this is whyubes still matter.

With a Name Like Schiit, You have to Sound Goodhad great time talking to Jason and Rina at the Schiit table. Jason Stoddard is a

TCJer and he even used my software in designing his tube headphone amplifier, theValhalla. Check out the specifications on this cool tube-based headphone amplifieractually, it is hot to the touch and draws 40W from the wall socket).

just do not understand how Schiit can make a such an amazing headphone amplifier,

n amplifier that is made in America (not China), that uses such high-quality partsAlps, Nichicon, Wima, Dale, and Neutrik), that uses internal power transformers and

not a switcher wallwart, that comes with a 5-year warranty, that sports four tubes anddoes not use a solid-state output buffer, and that sells for only $349. Amazing stuff.

chiit also makes a solid-state headphone amplifier, the Asgard (with a name likeAsgard...), that sells for only $249. From the Schiit website:

"The Asgard is a fully discrete, Class A, single-ended FET headphone amplifier with no

overall feedback and a noninverting circuit topology. Its high-current design makes it

uniquely suitable for low-impedance headphones."
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f I didn't already own about ten headphone amplifiers, I would certainly buy aValhalla from Schiit. My only wish is that they paint their boxes flat-black enamel

aint. Here's why:

Typical Emissivity o f Various SurfacesMaterial Finish Emissivity

Silver Polished 0.02

Copper - commercial polished 0.03

Aluminum polished 0.04

Tin bright 0.04

Aluminum rough 0.06

Copper machined 0.07

Nickel Plate - dull finish 0.11

Stainless Steel - alloy 316 0.28

Steel - rolled sheet 0.55

Copper - thick oxide coating 0.78

Steel - oxidized 0.78

Aluminum - anodized (any color) 0.80

Paints & Lacquers - gloss finish 0.89

Paints & Lacquers - flat finish 0.94

Taller feet would also prove effective in keeping the little amplifier cooler.

At the Other $$$ Extremesaw a lot of interesting audio products at the RMAF and when I asked the sellingrice, the answer was usually $20k, $30k, $40k, $50K, $60k, $70k... Maybe it was myyebrows doing somersaults that gave away my astonishment, for the the next thing I

heard, over and over, was "Sure it's a lot of money, but don't think that we are makingny money off of it." I never knew that such munificence existed in high-end audio.

When I think about zero-profit enterprises, $10k record clamps and $70k speakers

never come to mind. Or, perhaps, I got it wrong, maybe what I was being told was thathey haven't sold any of $70k speakers and they were still searching for their firstustomer. Nonetheless, it seems to me that if a speaker does not sound better than a

Quad 2805 (less than $10k), it should not cost more than a Quad 2805. Either way,here was a lot of super expensive gear on display, even if no one was making any

money selling it. Strange, very strange.

o, the only thing I can conclude is that the nice people at Schiit must be making akilling. Of course, ours is a bad economy and I heard from many American firms thatf it weren't for the export market, they would be out of business. I also encountered

near universal scorn and derision for high-end cable manufacturers. I can understandhe logic behind such animus, as it must be painful to see $20 worth of wire selling for

more than your power amplifier or loudspeaker or turntable... These cable guys run a


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markup that would make a jewelry store owner blush. Sure, cables can provemportant, but they should never cost more than the rest of your system. Or am Ietting this wrong? Would $20 speakers hooked up with $10,000 cables sound muchetter than $10,000 speakers hooked up with $20 cables?

New BooksThe RMAF was not just about audio gear; other items were on display and for sale,uch as records, CDs, and books. Finding any new audio-related books is amazingnough, but finding two exceptional new audio books a treasure find. The first is by

Robert Cordell and it is titled,Designing Audio Power Amplifiers.

This handsome 600-page book covers aspects of solid-state power amplifier design,rom the basics to the secrets only the masters know. The following table of contentsives you a good idea of much material is held between the covers:

Part 1: Audio Power Amplifier Basics1. Introduction

2. Power Amplifier Basics

3. Power Amplifier Design Evolution

4. Negative Feedback Compensation and Slew Rate

5. Amplifier Classes, Output Stages and Efficiency

6. Summary of Amplifier Design Considerations

Part 2: Advanced Power Amplifier Design
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7. Input and VAS Circuits

8. DC Servos

9. Advanced Forms of Feedback Compensation

10. Output Stage Design and Crossover Distortion

11. MOSFET Power Amplifiers

12. Error Correction

13. Other Sources of Distortion

Part 3: Real World Design Considerations14. Output Stage Thermal Design and Stability

15. Safe Area and Short Circuit Protection

16. Power Supplies and Grounding

17. Clipping Control and Civilized Amplifier Behavior

18. Interfacing the Real WorldPart 4: Simulation and Measurement19. SPICE Simulation

20. SPICE Models and Libraries

21. Audio Instrumentation

22. Distortion and its Measurement

23. Other Amplifier Tests

Part 5: Topics in Amplifier Design24. The Negative Feedback Controversy

25. Amplifiers without Negative Feedback

26. Balanced and Bridged Amplifiers

27. Integrated Circuit Power Amplifiers and Drivers

Part 6: Class D Audio Amplifiers28. Class D Audio Amplifiers

29. Class D Design Issues

30. Alternative Class D Modulators

31. Class D Measurement, Performance and Efficiency

As soon as I have finished reading Bob's book, I will give it a proper review; but if youhave any interest in solid-state or hybrid power designor audio design in general, asmuch of what Mr. Cordell writes about also applies to phono stages and electronicrossoversthen be sure to drop many hints to your loved ones that you would enjoyeceiving this book for Christmas. Well written, thoroughly researched, beautifullyllustrated, highly recommended.

The second book is not a book, at least not in the typical sense, as it a bookzine. Amagazine as thick as a book, but ad freethis is the answer to the question What isLinear Audio? Jan Didden, famous for his many articles in Audio Amateur andaudioXpress, is the editor and publisher. He has brought out Volume 0 (yes, zero) andilled it with a who's who of audio design:

Blhbaum, FrankBryner, Andy
http://linearaudio.net/author_chosen.php?naam=Bl%C3%B6hbaumhttp://linearaudio.net/author_chosen.php?naam=Brynerhttp://linearaudio.net/author_chosen.php?naam=Brynerhttp://linearaudio.net/author_chosen.php?naam=Bl%C3%B6hbaumhttp://www.linearaudio.net/


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Cordell, BobDidden, JanGaertner, Jean-ClaudeGerhard, JoachimLinkwitz, SiegfriedNousaine, TomPass, NelsonPolisois, AriSelf, DouglasSimon, Ed

Touzelet, PierreWouda, RenYaniger, Stuart

From theLinear Audio website:

How -Linear Audio is a printed publication, published in a schedule thatwill be determined by available content of the required quality level. Apublication of minimum two issues per year (April and September) of atleast 120 pages of technical content is anticipated. I call it a 'bookzine'.

Linear Audio will be sold on-line throughwww.linearaudio.net

By whom - Linear Audio will be published by Linear Audio Publishingfrom The Netherlands. Content will be selected from submissions from

professional and serious amateurs and DIY-ers alike, the sole criterionbeing the quality and timeliness of the content.

For whom - Linear Audio is meant for anyone who is interested intechnical audio developments or who wants to contribute to them. Beingemployed in audio engineering is not a requirement at all. Happy reading,happy writing, happy building and happy listening!

Loudspeaker, solid-state, and tube design articles abound in this 169 page bookzine.And those 169 pages are ad free. Another way of looking at it that most magazines run

bout 50% content and 50% ads; thus,Linear Audio would have been 338 pages longhad it been filled with ads. In addition, regular magazines engage in funny math toonvince their advertisers that they are getting their money's worth, such as printing

wice as many magazines as they have subscribers. In other words, the ads pay formagazine's printing. WithLinear Audio, the reader pays for it all. Sure that is all verynice, but can't I just read about audio off the net and pay nothing? Indeed, but high-quality articles like these deserve to be printed, which would certainly cost more in

aper and toner or ink than the cost of this beautifully put together bookzine.

n short, also highly recommended.

Next Timehave to come clean, none of what I just wrote was what I had intended to write. Ilanned on writing about OTL output stages and split-load phase splitters. I will try toatch up soon. In the mean time, be sure to check out the new CCA PCB and kit (only

45 for the PCB and 20-page user guide and only $99 for the PCB and all the partsesistors, capacitors, rectifiers, LDO regulator, LM334 CCS, tube sockets, standoffs and

O-rings, except the tubes and coupling capacitors) at the GlassWare Yahoo store.Thanks.

//JRB

< Back www.tubecad.com Copyright 1999-2010 GlassWare All Rights Reserved Next >
http://linearaudio.net/author_chosen.php?naam=Cordellhttp://linearaudio.net/author_chosen.php?naam=Diddenhttp://linearaudio.net/author_chosen.php?naam=Gaertnerhttp://linearaudio.net/author_chosen.php?naam=Gerhardhttp://linearaudio.net/author_chosen.php?naam=Linkwitzhttp://linearaudio.net/author_chosen.php?naam=Nousainehttp://linearaudio.net/author_chosen.php?naam=Passhttp://linearaudio.net/author_chosen.php?naam=Polisoishttp://linearaudio.net/author_chosen.php?naam=Selfhttp://linearaudio.net/author_chosen.php?naam=Simonhttp://linearaudio.net/author_chosen.php?naam=Touzelethttp://linearaudio.net/author_chosen.php?naam=Woudahttp://linearaudio.net/author_chosen.php?naam=Yanigerhttp://www.linearaudio.net/http://glass-ware.stores.yahoo.net/http://www.tubecad.com/2010/12/blog0195.htmhttp://www.tubecad.com/2010/10/blog0193.htmhttp://www.tubecad.com/2010/10/blog0193.htmhttp://www.tubecad.com/2010/12/blog0195.htmhttp://glass-ware.stores.yahoo.net/http://www.linearaudio.net/http://linearaudio.net/author_chosen.php?naam=Yanigerhttp://linearaudio.net/author_chosen.php?naam=Woudahttp://linearaudio.net/author_chosen.php?naam=Touzelethttp://linearaudio.net/author_chosen.php?naam=Simonhttp://linearaudio.net/author_chosen.php?naam=Selfhttp://linearaudio.net/author_chosen.php?naam=Polisoishttp://linearaudio.net/author_chosen.php?naam=Passhttp://linearaudio.net/author_chosen.php?naam=Nousainehttp://linearaudio.net/author_chosen.php?naam=Linkwitzhttp://linearaudio.net/author_chosen.php?naam=Gerhardhttp://linearaudio.net/author_chosen.php?naam=Gaertnerhttp://linearaudio.net/author_chosen.php?naam=Diddenhttp://linearaudio.net/author_chosen.php?naam=Cordell


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