volume fluctuating

[scole]

the amps volume seems to be going up and down by itself. could this be a bad rectifier? how do i diagnose this problem?

[Intergalactic Tourister]

Shot in the dark... it may be oscillation caused by a bad coupling capacitor... or perhaps too high a value replacement.

[g1]

What kind of amp is it? If it has an effects loop then the loop jacks are the most likely suspect.

[scole]

ita a tweed super clone.

[Intergalactic Tourister]

To diagnose the problem:

I can't guarantee you have oscillation- But if it is then check the coupling capacitors. Good place to start. In the preamp stage if I go above 0.22uf output I get oscillation. You may have unintentionally installed a 0.22uf rather than a 0.022uf if you know what I mean.

Also, check the grid stop resistors. Does your amp have them? If so, maybe they are the wrong value. If not, try something like 15k to 68k. But first check your coupling caps.

[scole]

its not a new build. the amp is 8 years old. this problem just started.

[Intergalactic Tourister]

Any luck?

If you switched out a tube(s) recently... go ahead and put a newer or older one in. I've personally had experience with a Groove Tube that caused oscillation. I simply switched out the tube and it stopped. However, the Groove Tube doesn't cause it in my other amps.

Still, not a lot of info to go by.