100W Ultimate Fidelity Amplifier

Nice work, yes R8 (560R) affect total gain, if you increase value to 1k2 it will reduce gain.
Regards
so which schematic is correct ? value of R2,R8 is reversed
 

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I have question about gain.. Is It R8 value, which affects total gain? When I will Increase value from 560R let's say to 1k2? Can someone explain me, how can I find feedback resistor? :) Next question is about maximum PSU voltages, and bias for all apex amp. Is it possible to make some table, because I think its still repeated question.. Thank you...
Max, that input stage uses positive feedback. It is bootstrapped to increase the AC input impedance.

Be very careful with changing any of the component values around the input stage.

Positive feedback is very sensitive to tiny changes.
 
Max, that input stage uses positive feedback. It is bootstrapped to increase the AC input impedance.

Be very careful with changing any of the component values around the input stage.

Positive feedback is very sensitive to tiny changes.

my problem is, that opened input produce adible hum.. its better, when i connect some input device, but hum is still audible...from my point of view is input too sensitive...any other suggestions?
 
I like the performance of this protect, but it works only in rails supply up to 40VAC.
What are the changes if i want to use separate 18-0-18 up to 24-0-24 VAC in order to use in higher rails power amp?
 

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