gain drop

[goneloco]

Hello
I have a problem that started recently with my mark v head(stock tubes).
While I'm playing, the gain will drop dramatically,but when I cycle back through the channels the gain will come back.
please help with your thoughts?? minor tube problem?? which one should I switch out?? or a bigger problem??

thanks for anyone's time

 

[goneloco]

bump??

 

[Nermel]

Tubes, tubes and more tubes

 

[JOEY B.]

Sounds like one of those quality MESA branded JJ 12AX7's is starting to flake out. Try a known good preamp tube in each slot, swapping one at a time, to see if the problem persists.

 

[eudaimonia02912]

Very highly probable that it's a tube. Is this only happening on a particular channel? (E.g., if this only happens on channel 2, then it's the tube in V2.) When this happens, are you also having problems with the effects loop or reverb? If so, you might be able to narrow down which tube it is without having to switch them one by one until the problem goes away.