Dear Shaan,
Since "we" have a nice PCB now, could you point us to your variation of the SSA.
Now I can't find it.
Many thanks,
M.
Here you go.
LINK -> http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-272.html#post3123429
whooa... thank you very much sir!..... PCB for Shaan's schematic was done this weekend
Regards Alex.
...Sir, would you upload bottom pattern and top component layout for toner transfer.. please.
regards,
naf
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wow! you're very fast sir... thank you.... thanks all for kidnes and suggestion
Regards Alex.
Probably not, not only am I a investor and part owner of a couple of companies in the commercial sector in audio business but I also have access to design principles through association. Just look at past 12 years of Nad, 98 % have been CFB, a prominent german PA company practically only use CFB ( the design is 99 % like this presented by lazycat except it is from 1994 and thermal issues revolved), all Cyrus amps since III are CFB, Pioneer, Accuphase, so many german and swiss High end amps, 90 % marantz models since 2004, the list just goes on and on.
You dont have the info to make the statement you did on the % of CFB amps Im afraid. Maybe you could ask member Jacco here at DIYaudio, hell have a much better idea than yourself as he follows the audio world pretty closely.
I would guess nearly all are non inverting
1st stage will be inverting as usual - out of phase
2nd stage non inverting as usual - back in phase again
an inverting design would have a very low i/p impedance typically 50 - 100R
Andrew, Mike is right. There are three CFB amps I can recall now that used inverting second stage and so the feedback is taken back to input node and not the emitters of input pair which is probably what you meant with your question. Two were designed by Stan Curtiss and the other is german by Audiolabor.
Because CFB is a bad definition (is poorly named), i think not all of us ;-) accord themselves on it.
There is no question of Voltage or Current in the matter, or, to be more accurate, and according to Mr Ohm, we always use both of them together.
All the matter is to avoid any additional pole in the feedback path.
I propose this definition:
"Current feedback (So called) is a global negative feedback where output signal is mixed to the input signal without active parts in the feedback path."
This means the amp itself is inverting and exclude differential input stage where signal is applied to the non inverting input and CR to the inverting one.
Just to demonstrate and fun, we discussed early in this thread a CF SSA with a differential stage for symetrical input.
I do not want to argue with homemodder and i'm certainly less hype than him on the market knowledge.
The only thing i know is how it was difficult to me to find a TRUE Solid state commercial or DIY CFB amps since (between 1970 and 2000), each time i was looking for one.
As it is difficult to find a more talented and nice printed circuit designer than sir Alex, or audio designer equal to L.C. ;-)
Esperado, tell you what Ill post the schematic of a commercially available design that led to the design of dartzeel just for fun. The designer of dartzeel claims it took him 16 (something like that) years to come up with it but he was or so he claims friends with the designer of this said commercial design. The commercial design is at least 30 years older than the dartzeel. 
I can post Sony CFB from the 90s or perhaps a Pioneer or two from late 80s or early 90s.
I can post Sony CFB from the 90s or perhaps a Pioneer or two from late 80s or early 90s.
No thats what he claimed during an interview of the dartzeel amps. I think he is in his late 50s now. Just a marketing ploy to get very foolish
people to pay 150 000 euros for stereo amp.
Absolutely! Don't he realize he deserve-himself, looking as the worse engineer ever: i wonder which manager can afford an engineer witch take 16 years (or even 1) to design an amp.No thats what he claimed during an interview of the dartzeel amps. I think he is in his late 50s now. Just a marketing ploy to get very foolish
I imagine.. when the amp is finished, parts are obsolete and no more available, back to the starting point. Loop...
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Thank you dear Shaan, but the link bites its tail and returns the same page
M.
Here it is!
Attachments
Ah! Thank you, Shaan!
I would like to, if my first attempt is a success, make a modular amp and try different output sections...for example, I wonder how a Sziclai pair would work here, or if it would ruin the performance or if it is just impossible to use it...for that, I will have to study first what the *** is a Sziclai pair, to begin with
I would like to, if my first attempt is a success, make a modular amp and try different output sections...for example, I wonder how a Sziclai pair would work here, or if it would ruin the performance or if it is just impossible to use it...for that, I will have to study first what the *** is a Sziclai pair, to begin with
When I first built it I had oscilation around 10 or so MHz and had samll caps <33p across NFB resistors. Others that built it did not have the oscillation (I think). Later found the reason for oscilation was due to stray capacitance between gate/source and heat sink.
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