F6 Amplifier

The F6CC development continues. I sent a pair of boards to BuzzForb to see what he can do with it.

I am in the tweaking phase, exploring different output FETs, open-loop gains, ... As I said earlier, the PCB design is a "Swiss Army Knife", allowing a variety of options, and lots of tweaking.

I currently am listening at an extreme end with bias=1.3A, gain=3, giving about 26dB feedback, and a damping factor around 20 into 8 ohms. With the pots tweaked to minimize the harmonics, it sounds more like an F5 (neutral) than an F6. But with less feedback or less bias current the harmonics increase, and of course output FET source degeneration can be increased, and push-pull gain factors can be changed to modify H2.
 

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