GC SuperSymmetry part IV

Nelson Pass · 22nd June 2004, 10:46 PM

Then there are those who only want Chips in their amp.

www.passlabs.com/np/GC-SS-4a.pdf

In this case the output stage consists of both series and parallel
chip amps. The voltage sources you see introduce differential
DC offset between the two parallel chip amps, which allows
a DC bias current for the amps which can be set arbitrarily.
This DC bias is not seen by the load which sits beween the
output resistors. The damping factor remains high, as it is
enclosed by the GC input pair.

I leave it to you to decide what constitutes an acceptable
bias current for the chip amps.

Like the other versions, note the chip amps each having their
own local (nested if you like) feedback loops. Adjusting these
loops will give a wide range of performance/stability character.

As with version 3, we can easily arrange to invert the input
pin polarities of the chip amps, but that would be a trivial
variation after the first example.

There will be a prize for the first person to find a mistake
in any of the four.

gl · 22nd June 2004, 11:55 PM

Nelson,

In the first version there is a missing value for R3.

Graeme

Nelson Pass · 23rd June 2004, 03:39 AM

This being a symmetric circuit, I invite you to look at the
part on the mirror half.

jh6you · 23rd June 2004, 05:59 AM

Confused:

The input stage chips of 4a should have -/+, not +/-. I'm really confused.
And... and I clearly see the complexity inside Nelson's brain while he speaks out so simple.

jh6you · 23rd June 2004, 10:02 AM

Pepper:

I see that the four output stage chips of 4a are utilized only with their half capacity at maximum. If so, 2a or 3a are more intersting potential projects?

And... and if it is full of emptiness inside his brain, he would speak out very much and long.

moamps · 23rd June 2004, 12:23 PM

Hi,
paralleled chipamps haven't same AC input signal (or always same tracking difference) what means that one is dynamically loaded with very low impedance from another. This design doesn't look good to me, but maybe I'm wrong.
Regards
Milan

Nelson Pass · 23rd June 2004, 05:33 PM

Quote:

Originally posted by jh6you
Confused: The input stage chips of 4a should have -/+, not +/-. I'm really confused. And... and I clearly see the complexity inside Nelson's brain while he speaks out so simple.

No, I believe that's correct. We just keep flipping the polarities
until it comes out.

jh6you · 24th June 2004, 07:09 AM

Red.hot.chilly.pepper:

The 4 inside should have the flipped polarities. Otherwise, I give up this project...??? Because of

.........................

uli · 24th June 2004, 07:46 AM

Quote:

Originally posted by jh6you
Red.hot.chilly.pepper:

The 4 inside should have the flipped polarities. Otherwise, I give up this project...??? Because of .........................

You need not give up.

As the 2nd OPA gets its inputsignal from the supply shunt resistor

of the first one the phase is 180°.

Imagine driving OPA1 with positive signal -> output gets positive

thus drawing current from PSU -> this in turn leads to more

voltage across that shunt -> this again leads to negative voltage

at the capacitor coupled input of the 2nd OPA -> Bingo!

Uli

jh6you · 24th June 2004, 08:42 AM

Mist.on.my.shoulders:

I well arrive to your Bingo position. Thanks.
After all of that, where to where the supply currents of the second OPAs flow? From this point, my face starts to have harmonic distortion.

22nd June 2004, 10:46 PM	#1
Nelson Pass The one and only Join Date: Mar 2001	GC SuperSymmetry part IV Then there are those who only want Chips in their amp. www.passlabs.com/np/GC-SS-4a.pdf In this case the output stage consists of both series and parallel chip amps. The voltage sources you see introduce differential DC offset between the two parallel chip amps, which allows a DC bias current for the amps which can be set arbitrarily. This DC bias is not seen by the load which sits beween the output resistors. The damping factor remains high, as it is enclosed by the GC input pair. I leave it to you to decide what constitutes an acceptable bias current for the chip amps. Like the other versions, note the chip amps each having their own local (nested if you like) feedback loops. Adjusting these loops will give a wide range of performance/stability character. As with version 3, we can easily arrange to invert the input pin polarities of the chip amps, but that would be a trivial variation after the first example. There will be a prize for the first person to find a mistake in any of the four.

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22nd June 2004, 11:55 PM	#2
gl diyAudio Member Join Date: Dec 2003 Location: Sierra Foothills - California	Nelson, In the first version there is a missing value for R3. Graeme

23rd June 2004, 03:39 AM	#3
Nelson Pass The one and only Join Date: Mar 2001	This being a symmetric circuit, I invite you to look at the part on the mirror half.

23rd June 2004, 05:59 AM	#4
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Confused: The input stage chips of 4a should have -/+, not +/-. I'm really confused. And... and I clearly see the complexity inside Nelson's brain while he speaks out so simple.

23rd June 2004, 10:02 AM	#5
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Pepper: I see that the four output stage chips of 4a are utilized only with their half capacity at maximum. If so, 2a or 3a are more intersting potential projects? And... and if it is full of emptiness inside his brain, he would speak out very much and long.

23rd June 2004, 12:23 PM	#6
moamps diyAudio Member Join Date: Oct 2002 Location: Croatia	Hi, paralleled chipamps haven't same AC input signal (or always same tracking difference) what means that one is dynamically loaded with very low impedance from another. This design doesn't look good to me, but maybe I'm wrong. Regards Milan

24th June 2004, 07:09 AM	#8
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Red.hot.chilly.pepper: The 4 inside should have the flipped polarities. Otherwise, I give up this project...??? Because of .........................

24th June 2004, 08:42 AM	#10
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Mist.on.my.shoulders: I well arrive to your Bingo position. Thanks. After all of that, where to where the supply currents of the second OPAs flow? From this point, my face starts to have harmonic distortion.

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