I've been repairing an old tube amp that was abandoned and missing some parts. There were no schematics online and only a few mentions of the amp and brand at all. I ended up drawing my own schematic by drawing everything that was still there and making some educated guesses about what was missing. And adjusting a few values after I got it working. It's an Ampower Tremolo 80 and seems to have been made in Chicago from what I can guess. When I found this amp, it had 6v6 tubes (dead) and 5y3 rectifier (also dead) and the push pull pair was driven by a cathodyne circuit around a 6j5 tube. It took me some time to understand how the push pull was being driven by the single 6j5 tube and it was really tempting to rewire it for something like a 12au7 or even a 6sn7 (two 6j5 in same package) but it does work even though I can't quite get my brain wrapped around how that single tube is able to drive both sides of the push-pull pair ... and it sounds really good so I'm glad I left it stock just to get a feel for what amps were like back then. The preamp is three 6SJ7 tubes with FOUR instrument inputs and TWO microphone inputs. I'm guessing this was the only amp on stage back then and the pedal steel player had it in front of him (there is a lever that pokes out the back where you can change the tonality of the output section - it patches in capacitors between the output tube plates to bleed off the highs) and the singers plugged their mics into the amp too. (just a guess - I wasn't alive in the 40's). Oh, I forgot, it also has tremolo ---- you can only adjust intensity, not the speed, but it sounds good and must be one of the first amps with tremolo. Once I got it running, the voltages are high enough that this would have fried any vintage 6v6 tubes but I was using Ruby 6v6GTA-R and they were right close to the limit (and sounded awesome). With 6L6GC tubes and a 5U4GB rectifier the output tubes are just loafing along dissipating 19 watts each --- and I think that's about exactly what the 6L6 tubes back then were able to handle. The speaker that was in it can't be the original - though it is really old, but it's a HiFi speaker with a whizzer cone. And that brings me to my question. I have three candidates here and curious if you guys have strong opinions on which speaker would be best. I have a vintage '56 Jensen P12Q, a vintage Fender maroon/gold Jensen C12N and an old EVM12L (the EVM just barely fits - but it does fit). The amp is super clean sounding and not enough gain to really overdrive things - I moved the output from the instrument channel to drive the input of the mic channel and you can now overdrive that second stage really well - it still isn't able to drive the power amp as hard as I'd like though. I'll have to think about increasing the gain of the driver but that cathodyne circuit still baffles me. Any thoughts on driving the power section harder?