I don't actually need more gain, but with this change, I could have the same gain, without ever seeing the OD1 LED clip, even a little bit.

Curious what the tone would be like.

Quote from: rnolan on November 05, 2024, 10:50:42 PMHey Kaz, maybe you should get a 3TM, gain city LoL.

  .and THEN some!

Hey Dante,

    If it were me, I would take a look at any resistors for discoloration, especially near the filter caps. I would also use a plastic rod, or some other non-conductive tool to move any wires or ribbon cables gently to see if that low side changes volume levels. Tapping with that tool in various places around the PC board might also reveal an area where the problem could be, (I would be doing this with a signal going through it, so be very careful where you touch).

   I think Richard's suggestion of freshening up the solder joints is a good one, after all they are pretty old, but also look for loose solder connections too. Solder joints can crack, and components can move, even slightly.

It worked through practice without any issue, so yay.

I didn't swap the cables to be sure it wasn't my MP-2 with the volume diff....I should have done that. I will take a look at it when I get back to the practice space. I was just going with it uneven to try it out...didn't troubleshoot at all.

The whole concept of the B200s being so simple is why I'm not intimidated by opening it up and fixing what needs fixing. It didn't look like that case had ever been opened, inside is pristine.

I will bring my Deoxit and clean out that pot again, then swap the cables and troubleshoot.

BTW: That amp gets LOUD

Hey Kaz, maybe you should get a 3TM, gain city LoL.

Hey Dante, well good news (ish).

So I'll start with the obvious, I assume you tried swapping the inputs and outputs so as to rule out difference in input signal level/lead and output to speakers lead/speaker.

Maybe clean the B pot again (can't hurt) and all the jack sockets, particularly the output sockets which take the most ware over time (unless you leave them plugged in and roll you speaker cables into the rack).

If that doesn't fix it, then re-flow all the joins regardless of how they look.

If all that doesn't fix it, then obviously something else is not quite right.  It may be the pot (or jack(s)) needs replacing   or something else in the B channel.  Hopefully it's not an output transistor IIRC they are hard to find.  But my understanding is they either work or don't so it would more likely be in the circuit that feeds them, maybe where the phase is split (similar to a phase splitter tube in a tube amp but done with transistors).  The B200s is not a particularly complicated amp.

I'll be watching this thread Dante,

  ...just in case I encounter something like that when I get around to my B200S.

BTW the D16/U9 circuit although it looks like a log amplifier is here used to protect the vactrol from recieving negative voltages.

Did you check the voltages comming out of U14, I think I send you list of voltages that are normal. BTW did you also check pin 3 of U9 is grounded?

I mailed it to him.