Popping noise driving me nuts!

[Dillow4092]

I'm getting this LOUD popping noise when I engage my pedals and it's making my amp basically unusable. Now I've tried two sets of patch cables, both very good quality (George L/Monster).

I'm using Mogami Platinum guitar cables. The head is a 74' JMP 50 that just got back from service (it was doing this before going) When the head is powered on there is a humming noise, louder than my other 50 watt head.

I'm powering the pedals with a Voodoo Labs PP2, but it makes the same noise with batteries. I've tried clicking the pedal on/off to clear any static, so I believe I've tried just about everything.

Is it possible there's a ground issue with the head? Should it be quiet with the volumes down/powered on?

This is really driving me crazy, and I'm out of ideas other than to not use pedals with the amp which is ridiculous.

 

[phsyconoodler]

The head is a 74' JMP 50 that just got back from service

Take it back and get the tech to actually test the amp.I'm betting one or more of your input jack switches are not grounding.

 

[Dillow4092]

Take it back and get the tech to actually test the amp.I'm betting one or more of your input jack switches are not grounding.

I was thinking it must be a ground issue somewhere also. This should be a simple test/fix correct? The noise when the amp is powered on, volumes down is bugging me as well.

 

[Atlas Stands]

sounds to me like a ground issue, I agree

 

[TimmyP]

Possibly some voltage us leaking onto the grid of V1.

If the pedals cause the problem with both amps, I'd suspect some output offset on the pedal.

 

[chervokas]

Possibly some voltage us leaking onto the grid of V1.

If the pedals cause the problem with both amps, I'd suspect some output offset on the pedal.

That's it, there's probably DC somewhere is shouldn't be in the AC signal path -- at the amp input on the output of one of the pedals. That's what causes popping. You can measure for DC offset with a multimeter to try to locate the source -- the amp, or a pedal. Might also try a different tube in V1.