I was originally going to post a couple questions but I think I have worked out all the kinks in my first from scratch design and build of a guitar amp. Most everything was salvaged from a 1946 radio/record player, gutted, and redesigned into a class A guitar amp. It was originally push pull with two 6V6 tubes over 8k of impedance but is currently a single 6L6GC over the same 8k. It took a lot of math and tinkering but sounds fantastic. I don't think I need to change a thing in regard to sound but perhapse anyone can offer insight as to any undesirable operating conditions. It is currently only biased at 70%. I hear i can take that to 90% with class A but I don't want to over work the transformer.
This is why I don't comment on guitar amp stuff. lol
Bobby. Fair enough. We all have our desire in amps. Just don't be dismissive of distortion. Everyone was after clean until the 40s or 50s or some shit. I forget the timeline. But then some people discovered distortion through broken speakers and overdriven preamps and some of the most amazing music came from it in the 50s and 60s. It just proves no one amp can do everything.
Why a tube amp then? Try a LM1875 on a board smaller then a saltine cracker. In any case. This amp is designed to be extremely clean compared to most guitar amps. Lots of headroom. But only just enough to where if you stick a pedal in front it starts to grind. Allows the pedal circuitry to shine a little.
I want super clean, I hate overdrive and distortion.
Guitar amps are a strange lot, things that would be horrible for HiFi seem to work fine for them, especially when you plan to overdrive them into distortion. Looks like you are having fun :)
Not sure if anyone is interested or not. An updated schematic. I'm still fiddling with the negative feedback.
I decided to unplug the dummy load a try a speaker after soldering more down. Some things I read online about guitar amp clipping suggeste. The clipping I have at full volume might be pleasant. It does sound great. I might leave it as is.
I tried adjusting the 22k and 2.7k resistor on V4 to try and center the clipping better but their was far less of an effect then I expected. I figured a work around, to lower the 100k resistor going into the 6L6 which would increase the amplitude on the output allowing me to lower the preamp gain giving more headroom, but I would prefer to learn how to correct the uneven clipping
I removed 20 feet of jumpers today soldering everything down. It seems to be hard clipping on only half of the wave when I push it to the limit of the output transformer. Does anyone know what might be causing that? It's happening in the last preamp stage. V4. Sounding fantastic though