• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

OP tube convertible PP amps?

not me but ....

... what are you going to do with the power supply? 845/211 need an offensively high B+ while 45 are run at lower plate voltage

... and what about the heaters? ... hugely different voltages and currents

... and the bias? again, so different

... OPT? you can squeeze a very high power out of the 845 while the 45 give just a few watt and the loads are very different for each of these tubes. I don't believe a single OPT can offer all these options

Probably a selectable 45/2A3, just to stay with DHT's, can be a simpler/achievable project. And if you have separate 2.5V heater supplies you can switch to 300B. You could also add a DC (current) heater to have more flexibility and simpler wiring (You will just have to adjust the sensing resistor of the current regulator).

:confused: :confused: