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Old 30th September 2012, 02:45 AM   #3211
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Break the rails and insert an R in series ith a D. Then a filter cap, so it's like an RC except an RDC. The varying nonlinear impedance of the diode has an adaptive effect, perhaps.
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Old 30th September 2012, 03:08 AM   #3212
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I always understood that its main goal was sag reduction, when outputs are fed from the same source.
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Old 30th September 2012, 03:27 AM   #3213
Jay is offline Jay  Indonesia
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Originally Posted by smartx21 View Post
I always understood that its main goal was sag reduction, when outputs are fed from the same source.
Yes. In this case, why is front end sag reduction or backward current must be prevented? What is the quantitative goal?
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Old 30th September 2012, 03:43 AM   #3214
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Thank-you, sirs, for the translation. (I have problems with acronyms ;-)
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Old 30th September 2012, 03:45 AM   #3215
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I think it has a mix of dynamic effects, including sag reduction depending on hat the R value and here it is placed.

A silicon diode has effective R of about .033/Id. R decreases ith Id. This is nonlinear, so if you give a diode a sine current, the average resistance ill actually be loer, and the voltage drop of the diode. Thus you have a dynamically changing RC filter. In fault conditions, it prevents frontend rail sag, but not entirely because it pulls some current to turn the diode back off.

I think this behavior must be helpful for the amp, because I've heard from many people that DRC is the ay to go.

Another effect may have to do ith ringing on the rails. If there is ringing through the diode, the sine current ill raise the diode's resistance, and then the resistance ill recover after the ringing is gone. It is like a dynamic auto-damping effect. Furthermore, the nonlinear action orks like an RF mixer to convert the resonance to other frequencies here their energy is lost from the resonance.

Series and parallel resistors have been used to tailor this effect. A small series resistor may be in order to damp any resonances through the diode's parasitic capacitance depending on ho large a diode it is.

So it seems the diode may be having the effect of breaking don rail resonances. This seems useful, but it may also be a sign that the rails are resonating and decoupling needs to be reevaluated. After all the diode can only help resonance after it has started (unless of course Id is chosen beforehand to apply the correct damping resistance).
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Old 30th September 2012, 07:14 AM   #3216
shaan is offline shaan  India
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Today, i connect my SSA to my speaker,
and for the first time i hear a beautiful sound of this Amp. Natural Vocal, nice bass and crisp treble and more important it stable..
You've got it! Well done.

So it looks like the SSA, although a symmetrical CFB amplifier with minimal compensation and LARGE bandwidth, can be built successfully by relatively fresh diy-ers without an explosion and can provide its elegant sound to anyone who wants to build it. IMHO, Naf's experience/experiments with the SSA is a useful and important addition to this thread and will encourage others to throw their prejudices and fears against CFB/symmetrical and embrace an idea that will bring wonders to them.

I am not exaggerating, I and one of my best friends here had an exam yesterday. On the way back I brought him to my house, he has been using AltecLansing's FX5051 5.1 PC speakers for two years now, and is very satisfied with them. I have auditioned those speakers and they indeed are one of the best PC speakers available here, and looks nice with the isobaric subwoofer.

I turned on the SSA and played some random music.

It was funny looking at his expressions.

The comment that came, "it feels like the speaker is way bigger, all over the wall, when I close my ears. And a feeling of life is there, damn I'm having goosebumps".

He spent straight three hours listening to this and that and before leaving his comment was, "This thing is not the average stuff man, it's got a heart. It's only a single small box and is hotter than my monster Altec. What did you put in it?"

Heh, what else could happen. I'll update more experiments with more people. With pictures in future.
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Old 30th September 2012, 07:43 AM   #3217
naf is offline naf  Indonesia
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Quote:
Originally Posted by shaan View Post
...
"it feels like the speaker is way bigger, all over the wall......
you express it very well Shaan ...
so who's next newbie diy'er want to build this SSA... you wouldn't regret!

.. six hour past playing music through this amp

Last edited by naf; 30th September 2012 at 07:47 AM.
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Old 30th September 2012, 09:16 AM   #3218
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Originally Posted by naf View Post
you express it very well Shaan ...
so who's next newbie diy'er want to build this SSA... you wouldn't regret!

.. six hour past playing music through this amp
There should be a text written on SSA sch:

Warning, use carefully, SSA could easily consume a big portion of your precious time.
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Old 30th September 2012, 09:23 AM   #3219
AndrewT is offline AndrewT  Scotland
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I went to post1 hoping, or expecting, to see a list, or index, to all the relevant schematics and important posts.

But, there is nothing to help me navigate around the 320+ pages.
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Old 30th September 2012, 09:58 AM   #3220
shaan is offline shaan  India
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LC, that line is so true.

Hi Andrew, I have a plan for solving the problem you mentioned. I am on it.
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