The output mosfet are biased with very low quiescent current, without feedback the amplifier will produce a lot of high harmonics. adding low value emitter resistors in the input transistors will increase the quiescent current.
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Yes I know that, here is the OPS and ClassA power amp with the same OPS.
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Damir, the Dr. Malcolm Hawksford error correction can also be a good solution for the output stage. One nice example is the output stage of the Jan Didden PAX amplifier.
paX: an error-correction power amp
paX: an error-correction power amp
Main problem is to find one OPS with friendly input impedance, as IPS(current conveyor) is quite sensitive to it.
The ops in isolation has THD20k of 0.007413% and whole power amp at the same level increase THD to 0.020025%.
HI
https://sites.google.com/site/opampbasedamp/BUFFER.png
0.016617% 20K 100W 4ohm
0.003030% 1K 100W 4ohm
0.037185% 20K 1W 8ohm
0.035481% 1K 1W 8ohm
it is not too bad
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I've got higher distortion (a bit) in that way. Could you explain what the stability would be better?
The Sziklai pair at the output is less stable than the darlington and it can easily oscillate, adding a baxandall pair to the mix is asking for troubles.
If you test your amplifier with a square wave, you will see that it will oscillate, then try my recommendation.
You were right.
Without input filter it oscillate, learning all the time something more, I don't have practical experience with Sziklai.Here is updated schematic with diamond and bootstrap. I think this is schematic worth to be build. Maybe someone will be curious enough to build it?
Looking at distortion figures and slew rate it should be very good amp and then with No Global Feedback.
Damir
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