The Revv Generator 120 is a high power modern head with four channels and many features offering lots of different sounds. It goes from a clean tone all the way to a very high gain tone and many tones in between.
This specific amp had a persistent crackling sound that was very annoying.
Turning down the master volume reduced but did not eliminate the crackling.
That was confusing at first as it wasn’t clear whether the noise was
being generated in the preamp section of the amp or the power section.
In the end there was a bad capacitor in the preamp that caused some of the crackling.
In addition, one of the JJ KT-88 output tubes was producing an additional and unrelated crackling sound.
Once both the bad cap and tubes where replaced, the amp was working fine again and sounding great with no issues.