Negative feedback adjustment on a Peavey Classic B

[bclemons]

I have a Peavey Classic 410 (hybrid). I was thinking it would be interesting to see what effect changing the amount of NFB on this amp would have. Can the negative feedback loop be modified for adjustment on this amp? I'm familiar how this works with a tube preamp, but I'm unsure if it can be done with a transistor preamp. I see on the schematic what appears to be the NFB loop with a 68k resistor in line from the OT heading back to the transistor (I assume PI) at the bottom of the schematic.


peavey-classic-b-schematic.pdf

[Enzo]

The NFB is part of the power amp, not preamp, in either type technology.

Yes, that pair of transistors is exactly that, a phase inverter.

NFB is NFB, it works the same with transistor phase inverter. The NFB is a 68k/10k voltage divider. You can play with that ratio if you like, though I'd be surprised if it did a lot.

[bclemons]

Ah, I meant to type PI instead of preamp in that sentence. Yeah, doing some research on this type of power amp, it seems like it is designed not to flavor what's being fed into it, but to be linear and not care too much about tube specs.

[Enzo]

That is exactly it. Peavey made their power amps to be strong and clean, the amp's tone would be generated in the preamp.