Originally Posted by Wally
Also, I consider these to be single channel amps with added gain that is cascaded. I could be wrong.....but when one set of tubes is used for all of the gain stages, it is a single channel amp imho. I see a bunch of solid state devices in those drive circuits....don't know what they do, but they are SS and I don't like the sound of the DRive in these amps????? I can like the straight ...no drive...sonics if things are set up in a certain way. The basis for this circuit harkens back to the 5F6A BAssman, so the basic sounds come from that thought....two tube gain stages before the tone stack, long-tailed PI, and fixed bias output section. The rest of the amp, that is the 'drives' and the solid state reverb circuit, is of little use to me.
You are correct that these amps are essentially one channel, with switchable additional gain stages. The solid-state components in the Drive circuit are JFETs that are used as switches to bring in the cathode-bypass caps when the amp is in the "More Drive" mode. They are not part of the signal path, and they are not the reason the drive on these amps sounds so bad. It sounds bad because it is a stupid design that was attempting to do a bunch of things with a minimum of tubes.