EF86 amp block diagram

[gdgross]

So here is my thought on the the amp to fill the cabinet that's been waiting for three years. (It's a beautiful render-style walnut cabinet made by someone I can't even remember anymore!)



I like the ideas in this amp:

• pentode front end
• switchable gain stages a la dumble
• simple tone controls
• low power output with power scaling MV control
• serial effects loop

Questions I have though:

• Is switching after the EF86 asking for noise in the relays? It is a high impedance signal after all. Should I add a FET buffer before the tonestack perhaps?
• Are two gain stages between the pentode front end and the PI too much? I'm not looking for a metal amp here, but one that has some good crunch and lead sounds. I could parallel the triodes or even use one of them for something else. DC drive a la AX84 perhaps?

I welcome your thoughts and critiques, and apologize for the big picture...