Weak OD compared to boost with CB at max - MA50C

[mejgus]

Hi guys!

I´m new to this forum and have been searching for similar issues as mine, but with no luck.

I bought my MA50C in july '10 and have approximately been playing with it 20-30 hours and a couple of gigs.
The problem is that I have to max the crunch balance in order to get a fairly decent sound/gain-level compared with the boost-channel, and this did not occur when it was new. I´m new to valve amplifiers so my first guess was to change the valves (5xTAD) but with no change at all...
Do you know anything about this and what could cause it?

[SteveD]

Welcome to the forum mejgus.

The only difference between the OD channel boosted and unboosted is a negative feedback loop across one section of one of the preamp valves. Unless there is a dry joint or the Crunch Balance pot is dirty there is little else it could be.

Can't you take it back to the store you bought it from as it may still be in its warranty period.

[mejgus]

Thanks for quick response!

Do you know which of the preamp valves that handles the negative feedback loop? Maybe it is some glitch with a valve socket..
I opened the amp and searched for dry joints but everything seems clean and well soldered.. will send it back to the store anyhow!
Good forum, really appreciated.

[SteveD]

Thanks for quick response!

Do you know which of the preamp valves that handles the negative feedback loop?

One half of V1.