MPP

O.k. here it is :) one 'Transresistance CFB BIGBT Amp, By FdW'

Yesterday it reached a new milestone, the 4AmpT net fuses where blown (several times). Extensive measuring and testing found nothing wrong, the amp was consuming 900Watt per channel and delivering (about) 600Watts per channel to the 'Carver Amazing, Platinum Edition's (loudspeaker panels), it was party time :)
 
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Yesterday it reached a new milestone, the 4AmpT net fuses where blown (several times). Extensive measuring and testing found nothing wrong, the amp was consuming 900Watt per channel and delivering (about) 600Watts per channel to the 'Carver Amazing, Platinum Edition's (loudspeaker panels), it was party time :)

Impressive... congratulations... wish I was there.
 
Due to a unfortunate event some days ago involving my bicycle and a dog I'm more or less immobilized and have bitten my way through this whole thread from where I once left it.
Wow!

The SE-Fet/folded-cascode input has been discussed ten years ago around here.

The second stage was with opamps, though. I build a few versions, it sounds promising, albeit I did not manage to get stable DC-conditions (this with a 9V-Block and a psu for the opamp-part). If I would do it again, I'd feed a CCS for the cascode-Q with a separate negative supply.
Or, if I'd been into tubes, build it with a p-fet input and fold-cascode it with a tube. This would give me some voltage swing to burn in a shunt riaa network.

Maybe, if my immobilization persists during next week my bench finds me sitting at it since a long time... (I can sit well, but not stand up (ough) or walk around (ooough)) :yinyang:

Rüdiger
 
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Joined 2002
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If I would do it again, I'd feed a CCS for the cascode-Q with a separate negative supply.
Or, if I'd been into tubes, build it with a p-fet input and fold-cascode it with a tube. This would give me some voltage swing to burn in a shunt riaa network.
Have you seen the circuit that the always interesting JC Morrison published on his blog a few years ago hybrid folded cascode Gm amp | lab jc.
It sounds almost exactly like what you're describing. I attached a copy of the circuit to make viewing it a bit simpler. I haven't built it but it looks very interesting.
---Gary
 

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