In an earlier post we discussed a '56 bassman 5e6-a amp I received. " '56 Bassman speaker load question " And I enjoyed a lot of helpful info from the TBer's that responded. This is regarding the same orphaned amp.
After re-capping the amp I discovered what appears to be a "mod", the purpose of which I don't understand.
The "normal" input jack is wired to both sides of the first pre-amp tube, in parallel. And from both coupling caps a wire returns to the "volume 1" pot.
The "bright" jack is wired directly to the "volume 2" pot, bypassing the first pre-amp tube. The bypass wire doesn't match the color of the rest of the wiring, yet it is
an old cloth insulated wire, (yellow/brown stripe).
From my schematic
it looks like the two inputs share
the 1st pre tube, one going to each side, and then back through the caps to the vol pots.
The end result is that Input 1 is very loud and distorts at a level of about 1/4 turn, while input 2 (the bright channel) can be maxed and still be at "practice level".
I am interested in why this was done, and what use it would serve, before I attempt to change it back. I am doing this as a hobby interest, not a tech, and while I have made successful repairs to a handful of amps, this is the first "tweed" I have serviced.
Any thoughts appreciated, thanks.