Guitar Gear Forum

my Randall RD50 combo started making a soft "whump" noise a few minutes after startup, then consistently every minute or so while playing. i was thinking probably caps, but i only paid $250 for this thing and didn't want to shell out more money than i spent on it taking it to a repair shop.

started simple ... swapped cables, exercised all jacks ... no dice.

for the hell of it i swapped in some extra 12AX7 preamp tubes i had ... noise gone! i rarely get lucky like that i guess it might have been the phase inverter tube?

lucky you. i fear every time i turn a tube amp on im gonna get the inevitable volume swell, a loud POP followed by a long and strenuous descent into no sound at all leading to a trip to either of the sketchy techs around me.

The same sort of luck happened with me, when I bought my THD Bivalve 30. It was simply a matter of reseating the tubes, and it worked flawlessly for the remainder of my ownership of that amp. Good on you.

I have a Orange Valve Tester... I'll be happy to test any GGF Member's tubes for return postage.
The Orange Valve Tester can also match tubes so, if you have a bunch of EL34s or 6L6s lying around, you could have a match set and not know it.