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Best way to eliminate ground loop noise?

#41
When I used to run FOH at certain clubs with bad power, we used to run our own ground wire to a stake out the door of the venue and into the ground, single coil guitar noise went away.

Another option to consider is a proper power supply that provides EMI/RFI protection.

@Frank Tuesday, that's fair but if someone has tied the neutral to the ground, you have much more pressing problems to deal with.
You really only know what's behind the walls if you put them there.

Best of luck chasing the noise though, it's no fun.
 
#42
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#48
Neutral and Ground are tied together in the breaker panel. That's how it's wired in the US.

For a three wire pieces of gear, the ground from the wall is also tied to the chassis. If you have two pieces of gear then the grounds between them are tied together at the outlet. When you run a audio cable between the two pieces of gear that share the same plug ground, then you have a loop between the two chassis and the plug ground. A triangle. This may cause hum, but not always. If it does then This is what ground lifts are for, you lift a ground at the audio connector and it breaks the loop.
 
#51
One thing that generally helps reduce the chances of noise is to ensure that any gear that is connected to your PA or monitor speakers is all on the same circuit.

With you having so much gear inter-connected it is possible that you have gear on different circuits but interconnected by mic cables or usb cables. Do you have all of your equipment powered by the same circuit? If not that is one of the first things I would try.

I've had noise problems when using a powered sub. PA plugged into power on one side of the stage and powered sub plugged into power on the other side of the stage and I've got a ground loop hum. Ran a power lead from the sub across the stage to the same power board the PA is using and all noise gone. The same thing happens if my bass amp is on a different circuit to the PA. As soon as it is connected to the PA with an XLR out of the amps DI to the PA and the noise appears. Power the amp off the same power board as the PA and all is good.
 
#52
I told my son, who is a journeyman Construction-A union electrician, about this thread. He said that what the OP is describing is often a precursor to an electrical fire and something that needs tracked down and fixed correctly quickly.

Most rooms are on one circuit. If the problem is on everything on the circuit it is probably either a loose neutral or a loose ground, or both, in the load box. It can also be a bad switch in the circuit. Regardless, it is something trying to leak to ground and ground is a high resistance path, so it's leaking where it can.

Bottom line, call a professional and get it fixed.
 
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#53
5andFretless said:
I told my son, who is a journeyman Construction-A union electrician, about this thread. He said that what the OP is describing is often a precursor to an electrical fire and something that needs tracked down and fixed correctly quickly.

Most rooms are on one circuit. If the problem is on everything on the circuit it is probably either a loose neutral or a loose ground, or both, in the load box. It can also be a bad switch in the circuit. Regardless, it is something trying to leak to ground and ground is a high resistance path, so it's leaking where it can.

Bottom line, call a professional and get it fixed.
Click to expand...

I had a master electrician check my panel a couple of years ago. He found some incorrectly wired multi-wire circuits, where neutral had too much current, and could have melted. Also installed some new breakers that trip with arcing.

Unfortunately, he reversed wires on one of the circuits. Didn't notice until 18 months later, when I noticed a red led lit on my computer UPS. My plug-in circuit tester confirmed the issue. Had another electrician fix it.

Seems like having a circuit tester is a handy thing...
 
#54
OldSchoolFlats said:
Seems like having a circuit tester is a handy thing...
Click to expand...

Better yet "an inspection". yeah, there's time and money in pulling permits but qualified inspection can find many problems. Good electricians are fine with having an inspector check their work. Insurance companies and realtors love them.

Arc Fault breakers are required in many places in homes these days. They can blow with a loose wire cause by the DIY push in wire outlets.
 
#55
My house was previously own by a guy that thought he could do everything himself. Everytime we went to fix or upgrade something the contractor was cussing. We didn't really go to deep into the electrical system until my son got into the trade and I started to put "smart home" things in place of the old electrical stuff. We thought the mechanical stuff was FUBAR until we started adding outlets and pulling new wires. My son declared my entire house an electrical hazzard and we pretty much rewired it over 6 months.

You would be amazed at the things you can find that are either out of code or flat out dangerous in a house like that.
 
#56
Bugliens said:
I was experiencing a nasty ground loop with my synth to iMac setup. I have the moog going audio out to my interface, which goes to the iMac via usb. The I have another usb going from the iMac back into the moog’s usb input. It was creating the worst hum/whine. Looking around online, I found someone suggesting one of these bad boys:

https://www.amazon.com/Compact-Mini...ocphy=9030967&hvtargid=pla-406164115633&psc=1

I hate that I sent 15 bucks to Amazon, but it solved the problem!
Click to expand...
Just curious, and I realize that after a while, hum can become "part of your tone" such that once it is gone, the perception is that your tone changed, but.... did you notice a change in tone, dropped frequencies, signal loss... once you started using this?
 
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#59
gstaats said:
What I would do is turn your amp on and leave it on - with no load. Plug the PC into the outlet. Does it buzz? If not, turn it on... Does it buzz? Only make one change, even if small, and listen 'till you get buzzed. When you find the buzzing, see if it is a single component, or, a combination of things.
Click to expand...
Scientific method baby
 

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