I've given some thought to that -- right now I'm mostly scrambling to get the theory part up while the class is running. I hope to circle back and figure out how to do some audio demos. It will be tricky to figure out how to isolate the individual circuits discussed in particular lectures so they can be listened to critically.
A guy from my hometown has something like 14 Dumble amplifiers. I heard a couple last time I saw him play. His name is Kenny Wayne Shepherd lol. Kenny and Alexander Dumble were very, very close and Dumble has had his hands in most of Kenny's amps. Of they aren't heavily nodded, they've been completely stripped of parts and rebuilt with whatever Dumble wanted to put in them. He has a Fender Bassman that has a Plexi style amp on the 2nd channel. All sorts of stuff. When he was here in his hometown last February, those Dumbles were SINGING! 😍
Nice video! So this bias scheme uses positive feedback back through R_G to set the bias point. Because of the capacitive input coupling, I assume that the positive feedback is only active at low frequencies. Could you just as well have used a constant voltage source at the other end of R_G, if you had one handy, or is the positive feedback scheme more than a neat way to derive the bias voltage that you need (providing more benefits)? Without R_K', the positive feedback would be more or less mu/(mu+1), so I guess that the reason to have R_K' is to control how close to one the positive feedback gets, thus controlling the bias point?
9:00 So the purpose of the treble bleeed capacitors is to let the treble through unattenuated while the volume controls bring down the volume of everything else? (I guess that gives something like a high shelf filter.)
I'd generally recommend against tweaking the amp itself, there's so many factors balanced against each other. I'd recommend trying commercial active attenuators just operating from the speaker connection side.
I'm guessing you play guitar. Someone that doesn't play wouldn't be this interested in guitar amps, etc...being such old technology. You have to WANT to learn about tube amps, which many guitar players do. Nt sure I know of ANY person that's wanted to learn about amps and WASN'T a guitar/bass player or musician of some type that would use one.
