Been a member here for over year and this is my first post. I have built many amps over the years, mainly 3-4 stage high gainers. Last year I built my first PP cathode biased amp and got a lot of go information from this site.
I recently purchased a 70's Fender Bassman 50 that has a MV. Currently working on replacing power filtering caps and doing some power section mods. I plan on leaving the normal channel as a 3 stage AB165 circuit and changing the bass channel to a Trainwreck Express type circuit or maybe a Komet 60 preamp. Since the bass channel used 2 triodes and the amp has a spare triode I should be all set.
What to get some input from you all and get some opinions, I'm attaching a quick drawing I did with a starting point. Let me know what you think
Since you have high gainers already in your arsenal then why don't you make that Bass channel into a Tweed channel with just a tone control and then some roll off switches to tame the bottom end at high volume levels.
You can put one switch on the tone pot and then a multi position rotating selector switch in the hole that had the Bass pot.
Also maybe even first off, if you will play the amp loud enough to clip the output stage then I would play around with lowering the value of the 2 220K inverse feedback resistors off of the plate of each output tube back to the PI section, as this has a very big effect on the overdriven harmonic content you hear!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
I did this mod to a Bassman. I'm primarily a clean player, so the cold clipper did nothing for me and I put the third stage back to stock. I did, however leave the tonestack alone, it is a nice contrast to the Normal channel, giving more variations, and, really gives some nice tone when the channels are jumped.
