I've been dealing with an odd noise issue for some time. Happens with my modded Twin or SMS connected to the Mc2100 or connected to the QSCPLX, though not as pronounced with the QSCPLX as the MC2100. Happens if guitar/cord is connected or not.
It's not a hum, but more of a deep hiss. Sounds like a water fall or white noise and increases as the volume is turned up and is gone when either power amps volume is at zero.
Also, both power amps are dead silent with the volumes cranked when no preamp is connected to them. I've tried all possible eliminations (different cords, different venues etc) with no results.
The only other thing I can think of is it's something going on in the preamps.
The odd thing is that when using the Twin as a combo on it's own, there is no power amp noise. Pretty quiet.
Any insight would be helpful. Thanks!
First show: 1973
Last show: 1994