We could also do a KT88 monoblock. Full U-L or get more complex with a seperate g2 supply and higher plate voltage, CFB winding v. E-Linear with a faux pentode diff amp to tame its output z issues. More power does have its attraction. Also, it does not matter to me that there are a few designs going on at the same time.

Everybody does not have to build the same amp. I can make adaptations/alowances for almost anything within reason. There is a limited amount of designs I have acutually built. If you( colectively ) are willing to step out *WITH* me to tackle a variant/improvement I'd be quite happy to do that.

Alright to hell with simple. We're building 813's. Filament requirements are 10V/5A per valve. We'll run ~400V for g2 and 900-1kV on the plates.

Just as soon as I can get a proper OPTx designed for 20-20 @ 100W or so, and we'll be in business. I know where I want to start, but time is creeping quickly. Cathode feedback like a Quad II, with plate taps for E-Linear drivers. I am most of the way done. I don't see anything jumping out of the Long Grass at this point. It is debatalbe wether or not further design work is warranted, or if I should just make one and see if it works as intended, and modify as required.

I think I need to plot some g2 curves for that valve and see what g2 voltage I want to run pentodes at for a 1kV plate supply. If only Maggies were more efficient, this mess would not be required....
regards,
Douglas