Ground hum

plus321 · Post by **plus321** » Fri Feb 29, 2008 11:10 pm

Hello,
I apologize for posting this here since it is not really a synth related question but it has to do with my patchbays and signal path so I think it is relevant.

I live in an older house and since I have moved here I have had noise problems and I listen to my recordings that I have made here and (in headphones) the noise is definitely noticeable and I don't want it hanging around anymore. The noise that I am referring to is a 60 hz ground noise.

I noticed that when I patch straight from instrument to mixer there is no problem and when I patch from mixer to patchbay to instrument there is when the patchbay is in the rack.

HOWEVER, when I take the patchbay out of its rack and set it on my larger metal rack, then the ground noise goes away until I take it off the rack or touch it. There is an obvious grounding issues somewhere and by putting it on the metal rack it is sort of grounding to that.

I don't know what to do and this is really pissing me off. I just want to write some music and have a tolerable S/N ratio. Does anyone have any advice?

My current thought is to find some way to ground the chassis of each patchbay to the rack since the noise goes away, but surely there is a slicker solution than this.

Thanks.

Post by **Maschinengeist** » Fri Feb 29, 2008 11:46 pm

The best paper I read so far on ground loop and how to get rid of it.

http://www.epanorama.net/documents/grou ... index.html

Hope that helps

plus321 · Post by **plus321** » Sat Mar 01, 2008 12:56 am

On second thought, I don't think it has to do with ground hum. I took one of the modules out of the patchbay and plugged in the cable to the mixer and moved it around the room and the noise differed in depending on where in the room I was holding the module and cable. The noise goes away the closer that I have the module to my big metal rack.

I think there are some stray EMFs in the room that are causing this.

Huppo · Post by **Huppo** » Sat Mar 01, 2008 3:26 am

If you're worried about ground loops there's one real easy way to eliminate that. Plug everything into the same outlet. Get some high quality multiple outlet strips and do them like a 'tree'. Make sure nothing in the signal path is plugged in anywhere else (including the computer). If any of your noise is caused by a ground loop it will disappear.

Of course you might want to add up the AMPs being drawn and make sure the circuit can handle that much load, but you can put a whole bunch of synths on an average home circuit (typically 20A here in the US) without even starting to overload it.