The Left Power Amp:
Single-ended triode; type 2A3 output tube, 6SN7 voltage amp/driver tube, & 5AR4 rectifier. Output level indicator is type 1629 'magic eye' tube, driven by a 6SL7. Output transformer is a One Electron type UBT-3. Power transformers and filter choke are Hammond's. The voltmeter shows cathode bias voltage of the 2A3; this 2A3 is a little low on emission, at 42 volts. Since this picture was taken, I've gotten a new matched pair of Electro-Harmonix 2A3's, and they both run right at 45 volts.