Hum when using effects loop

PlayItAll · 10-01-2007, 04:37 PM

I'm getting hum when using the effects loop on a Peavey Classic 30. It can be minimized or increased by physically moving the effects or even the cables around. Is this normal for these amps or might there be a grounding issue?

All the cables are good quality, shielded cables.

THANKS!!
Ed

TD_Madden · 10-01-2007, 06:28 PM

Does it hum if you plug a cable between the out/in jacks? If so, maybe a poorly-shielded cable (try all of them)....might be only one of them.

Do the effects hum if you plug them in between the instrument and the amps input jacks?

BTW, I've never had much of a liking to the way stompboxes sound when used in effects loops...they just seem to sound better when used traditionally.

Of course, there's always another stompbox that might help....Electro Harmonix's Hum Debugger......

Enzo · 10-02-2007, 12:54 AM

I'd say the issue is not in the amp, especially since moving the floor toys changes the symptom.

Don Moose · 10-02-2007, 01:51 AM

Quote:

Originally Posted by Enzo

I'd say the issue is not in the amp, especially since moving the floor toys changes the symptom.

Unless send and/or (especially) return have iffy grounds.

Hope this helps!

drewl · 10-02-2007, 03:25 AM

Most fx loops send a much larger signal out than what comes out of a guitar so they're overdriving the hell out of the effect.
The fx send usually works better with a rack unit of some kind that can switch between the two input levels.

PlayItAll · 10-02-2007, 03:53 AM

Thanks, everyone.

I am actually using a volume box in the loop to act as a sort of master volume for the amp. I'm able to balance the two channels out a little better with it. Normally, I never use effect loops (even my delay is in front of the amp) but the little volume control box quiets the background noise from the amp a ton. It was while using it that I noticed moving it around would change the hum from nothing to noticeable. I started trying out other effects in the loop and moving them around just to see and they all did the same thing which made me question the grounding of the efx send/return jacks. Right now, I'm back to my effects in front of the amp input and the volume box in the loop. As long as the volume box is at a 36.2 degree angle to the output tranny, then the hum is gone! :-) So I'm not worried about it.

Thanks again to all,
Ed

Enzo · 10-02-2007, 04:00 AM

Did you make the box yourself? Or did a friend make it? ANd if so, is it a metal box? And if it is a metal box, are the jacks the plastic type or metal? SOunds to me like your volume box is not shielded. Or if it is, the shielded box is not electrically connected to the jack grounds.

10-01-2007, 04:37 PM	#1
PlayItAll Member Join Date: May 2007 Location: Northeast USA Posts: 48	Hum when using effects loop I'm getting hum when using the effects loop on a Peavey Classic 30. It can be minimized or increased by physically moving the effects or even the cables around. Is this normal for these amps or might there be a grounding issue? All the cables are good quality, shielded cables. THANKS!! Ed

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10-01-2007, 06:28 PM	#2
TD_Madden Senior Member Join Date: May 2006 Location: Manassas, VA Posts: 693	Does it hum if you plug a cable between the out/in jacks? If so, maybe a poorly-shielded cable (try all of them)....might be only one of them. Do the effects hum if you plug them in between the instrument and the amps input jacks? BTW, I've never had much of a liking to the way stompboxes sound when used in effects loops...they just seem to sound better when used traditionally. Of course, there's always another stompbox that might help....Electro Harmonix's Hum Debugger......

10-02-2007, 12:54 AM	#3
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	I'd say the issue is not in the amp, especially since moving the floor toys changes the symptom.

10-02-2007, 03:25 AM	#5
drewl Senior Member Join Date: Jun 2006 Posts: 556	Most fx loops send a much larger signal out than what comes out of a guitar so they're overdriving the hell out of the effect. The fx send usually works better with a rack unit of some kind that can switch between the two input levels.

10-02-2007, 03:53 AM	#6
PlayItAll Member Join Date: May 2007 Location: Northeast USA Posts: 48	Thanks, everyone. I am actually using a volume box in the loop to act as a sort of master volume for the amp. I'm able to balance the two channels out a little better with it. Normally, I never use effect loops (even my delay is in front of the amp) but the little volume control box quiets the background noise from the amp a ton. It was while using it that I noticed moving it around would change the hum from nothing to noticeable. I started trying out other effects in the loop and moving them around just to see and they all did the same thing which made me question the grounding of the efx send/return jacks. Right now, I'm back to my effects in front of the amp input and the volume box in the loop. As long as the volume box is at a 36.2 degree angle to the output tranny, then the hum is gone! :-) So I'm not worried about it. Thanks again to all, Ed

10-02-2007, 04:00 AM	#7
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Did you make the box yourself? Or did a friend make it? ANd if so, is it a metal box? And if it is a metal box, are the jacks the plastic type or metal? SOunds to me like your volume box is not shielded. Or if it is, the shielded box is not electrically connected to the jack grounds.

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