RK effects loop causing LOUD HUM when engaged.....

[RoadKinger483]

Hey guys i was practicing this afternoon with my amp and I decided to engage the effects loop and experiment with some effects jst to see if i could find some cool tones. Anyway, when I engaged the loop the amp MADE A TERRIBLY LOUD HUMMING NOISE. I switched of the loop in the rear of the amp and then engaged it again; and the same thing happened. Could this be a faulty preamp tube?

 

[jbird]

Engage the loop without effects to diagnose where the hum might eminate from! :idea:

 

[NoGlassNoClass]

Ground loop. If your front-end FX and loop FX share the same power supply this is the result. If you're using a DC brick, or a 1-spot or similar to power your FX pedals, you pretty much need two of them...one for the front end and a seperate one for the loop. The Voodoo Labs Pedal Power has isolated outs so it shouldnt be a problem...or you can always use batteries. Ebtech and ART make hum-eliminating devices you can run in-line with your FX to break the ground loop.

 

[RoadKinger483]

Thanks guys for the feedback. Turns out that the preamp tube in V4 was the culprit. Swapped it out and it works fine now. Thanks for the suggestions though, I'll keep aware of those things as I experiment.