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Post by xgatex on Oct 15, 2005 11:22:57 GMT -5
Hello everyone!
I just bought another Peavey Ultra 60 combo(killer amps might I add).
It hums very slightly, which of course is more audible when the master is cranked. With the master half way, it is the volume of a wisper. With it on 10 it is the volume of a light conversation.
The only thing that makes it change in volume is the master volume. Nothing else effects it. I use humbuckers so thats not the problem.
Things Ive tried:
Unplugging the guitar and turning all of the knobs-Still, only the master changed the hum in volume.
Switched different wall outlets-no change, I had a Randall running on the same outlets without hum.
Switched the ground switch on back of the amp.-no cigar.
Switch the resonance switch-Actually, this did change the hum volume very slightly. It got louder going from tight to medium to loose.
Update: I tried something today that may help in trouble shooting. No matter what I do with the input of the amp I get a hum. Today I plugged a chord into the Poweramp In. I had total silence with the other end of the chord not touching anything. But I got the hum back by touching the end to either a piece of metal on the guitar or the amp chassis. Does this help?
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Post by Jerry P on Oct 18, 2005 9:45:15 GMT -5
Hum is commonly caused by a few things. Bad cables
Bad tube can cause hum - preamp or power - I'd look at this first in your situation - try a few new preamp tubes
Mismatched power tubes can cause hum A failed screen grid resistor in the power amp section can cause an imbalance which will cause a hum
Power supply filter caps - older amps
Ground loop with effects
There are other things, but these are the most common. Jerry
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