2:90 sudden rise in level/volume

[Armando]

Hello,

I'd like to know if there are any 2:90 owners who have experienced a sudden "rise" in volume/level after the amp has warmed up a bit. Nothing extreme, just a sudden boost. If I put the amp in stand by for a minute or so, and turn it back on, it's back to normal for another minute or so then the sudden boost happens again.

Anyone know the cause??

Thanks!!

 

[kdorsey]

Swap your power tubes and see if it persists. That can also be a wonky tube.

 

[BlackBart]

I read in another post somewhere that someone with same problem - volume pot.

I have similar issue with my 2:90, haven't pursued any fixes yet.

If the pot isn't sealed, I going to try contact cleaner first.

It took a little troubleshooting to figure out. It only happens on one side. I started with swapping A/B cables from the preamp and always stayed with the same side.

 

[crane]

If it happens only on one channel : +1 volume pot. Cheap fix, and if it doesn't fix it is not bad thing.
Both chanels : related to V1 preamp tube/component (or bad power trany with voltage variations, hope not)

 

[Pshooter]

The volume pots can be sensitive. Especially with a powerful preamp. PETE