Help with unwanted amp noise

M

mettleramiel

New member
Hello all! I have a small but annoying problem I'm hoping someone knows how to fix.

I'm recording live sessions with my band using pre-amp and d.i. outs from our amps so we can still hear live in the room but record directly into the interface as well.

The issue is with the e-drums. As soon as I plug in the d.i. or intrument (the output has a switch to let you choose) in to the mixer or direct to the interface, I get some fairly loud buzzing coming out of the amp. This noise is not present in the recording and is completely gone if the output is unplugged. The output is a balanced xlr.

Does anyone have any ideas as to why this might be happening? Thanks for reading!
 
Ground loop. If you have two spaces, it’s quite possible the ground for the recording gear is at a slightly different potential than the one the amp is plugged into. To prove it, run a mains cable from the power supply of the recording gear to that humming amp and see if it goes away. Some amps are class II products and don’t have a ground and often hum when your DI provide one. Sometimes you can cure this by finding an old XLR - XLR cable and disconnecting pin 1 removing the ground, and using that to go to the DI.
 
rob aylestone said:
Ground loop. If you have two spaces, it’s quite possible the ground for the recording gear is at a slightly different potential than the one the amp is plugged into. To prove it, run a mains cable from the power supply of the recording gear to that humming amp and see if it goes away. Some amps are class II products and don’t have a ground and often hum when your DI provide one. Sometimes you can cure this by finding an old XLR - XLR cable and disconnecting pin 1 removing the ground, and using that to go to the DI.
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Thanks! I'll give this a try in the morning
 
There is indeed a bit of a growing hum problem as more and more gear goes 'earth free' but when a hum comes about when an audio cable is CONNECTED you can bet your wedding tackle it is a ground loop.

Dissing pin one in an XLR is often a solution but once in a Bluey can cause Radio Interference problems, The fix is easy if you can solder. N.B. Some XLRs have a link from pin 1 to the shell, try removing that as well.

It is very useful for the gigging muso to have some 'problem solvers' made up in the gig bag. A pin one isolated 300mm XLR-XLR. One with a phase flip. Same for TRS jacks and, MOST of all, a digital test meter. Soldering kit is no bad thing either plus of course spares of everything like fuses.

Dave.
 
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