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Old 17th April 2012, 02:23 PM   #2421
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Quote:
Originally Posted by keantoken View Post
At 10KHz, which I think is a frequency representing compensation quality, distortion increases from .031% to .064%. I don't know whether output drivers will bring these figures closer. Distortion at 1KHz changes only barely from .0305 to .31. This is at 12V into 6R.

That sounds good to me, but right now I am invested in my own design.

I found 100R resistors in series with each Miller cap damped a resonance around 50MHz; could be much worse in real life.
OK, many thanks for the info keantoken.

Wish you the best outcome from your design, regards.

Last edited by Lazy Cat; 17th April 2012 at 02:26 PM.
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Old 17th April 2012, 02:30 PM   #2422
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Originally Posted by keantoken View Post

I found 100R resistors in series with each Miller cap damped a resonance around 50MHz; could be much worse in real life.
Or non existant, sims are far from perfect. Another case, it shows any triple EF outputstage as being unstable, but in real life a couple of million amps have been sold using it and perfectly stable.
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Old 17th April 2012, 03:36 PM   #2423
mikelm is online now mikelm  England
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I didn't like the sound of 100R in series with miller cap in my fetzilla but one cap with 100R and another in parallel without sounded fine.

I don't think KT is suggesting a tendency for oscillation rather just a tendency for low level ringing that spoils the sound.
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Old 17th April 2012, 03:55 PM   #2424
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I didn't like the sound of 100R in series with miller cap in my fetzilla but one cap with 100R and another in parallel without sounded fine.

I don't think KT is suggesting a tendency for oscillation rather just a tendency for low level ringing that spoils the sound.
This tendency once again being in sims, the question is if they are really there in real life.
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Old 17th April 2012, 04:59 PM   #2425
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This must be built and tested for, no point in speculating, it is not worth the time scrutinizing simulation when it is faster to solve the problem in a real prototype.

Ringing and oscillation can be virtually equivalent, if it's a resonance constantly perturbed, or if the oscillation is only sustained on negative half-waves or 5A excursions. It is best not to have any of either when it can be helped.

Last edited by keantoken; 17th April 2012 at 05:05 PM.
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Old 17th April 2012, 05:41 PM   #2426
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Originally Posted by homemodder View Post
This tendency once again being in sims, the question is if they are really there in real life.
No, you misunderstand me I was talking about what I heard when I tried it.

In simulation the 100R is excellent - in real life it makes the amp sound lifeless.
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Old 17th April 2012, 09:15 PM   #2427
hahfran is offline hahfran  Germany
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Inverting SSA
There is no way out for the purpose mentioned earlier the amp must be inverting.
Anyway with the feedback system shown earlier it has now a current input and a current output . But does this schematic make sense ? Of course it can be simulated.
Attached Images
File Type: jpg SSA inv.jpg (60.1 KB, 374 views)
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Old 18th April 2012, 06:57 AM   #2428
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Distortion of the shunt compensation can be brought down considerably by applying the entire Symasym compensation scheme, after you have added drivers.
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Old 18th April 2012, 08:29 AM   #2429
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Distortion of the shunt compensation can be brought down considerably by applying the entire Symasym compensation scheme, after you have added drivers.
This Symasym compensation scheme interests me. Keantoken, it would be very nice if you can elaborate it in a short form. Many thanks.
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Old 18th April 2012, 08:39 AM   #2430
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Hi igor0203

Well the amp is fully functional, playing music nicely, but it is still in R&D phase, so some more improvements will be tested before to go to conclusion of the project and say, this is the final SSA version.

What's happening now is an upgrade for CCS current injectors to SSA feedback bridge, since it was realized that the distortion spectrum is much more clearer with the use of high performance CCSs. And these are ready to build and installed into the amps. Both positive and negative CCSs are located on PCB size 30 x 45 mm (attached) and will be soldered to main PCB as add-on module. Will look quite professionally I tell you.
Any chance of listening this beast?

Last edited by igor0203; 18th April 2012 at 08:44 AM.
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