Amp problem - need help
 

I have this issue with my Randall RG100G3 100W combo: suddenly, the volume decreases, then comes back, then decreases again etc, on all 3 channels.

It has a 12AX7 preamp tube, replacing it may solve the problem? I have this amp for 3 years, been gigging and touring with it pretty much...

Thanks in advance !

yes. Sounds like the tube. My marshall 6100lm had this problem for a while, and preamp tubes were the issue. :)

I recommend you get a JJ.