Hum problem with a Fender Pro Tube Twin Amp

[mouton]

Hi,

I need your advice.

I have a Pro Tube Fender Twin Amp (100W, 2 channels clean/dirty) and everytime I switch the reverb on it hums (low pitched). Do you think this is due to the specific design of this amp and there is nothing to do about it or is it something that could be repaired?

The amp is recent, has new JJ tubes and is correctly biased.

Thank you very much for your help.

Cheers

[Buddha's Guitar Tech]

i worked on a vox with a similar sounding problem and if i recall, it was a grounding issue. The audio ground of the reverb return was miles away from the other audio ground.

Reverb pans are kinda like a single coil pickup - sensitive to RF etc.

[MBD115]

Have you checked all the caps to make sure they are not leaking DC? A bad cap can make noise. Check for DC voltage after the caps and also check the caps value with a meter (mine does that). Any cap that may seem suspect can be switch out to see if that helps. Sometimes a cap can go bad and leak DC through it, especially ones on high voltage.

Just a thought.
Good luck