Ground loop hum...help me further narrow down the fix
I relocated my equipment rack to a better location and multiple circuits to handle multiple amps and future growth. I went from two 15 amp circuits to three 20 amp circuits. Previously I had a ground loop hum that was fixed by grounding all the amps to each other. Now this fix no longer solves the issue.
THE CABLE COAX HAS BEEN RULED OUT. I removed the cable and the box and the hum remained. It is a matter of the amps being on multiple circuits. Amps are an nu3000 & an nu6000 for subs, and a Crown XLI 2500for R/L mains. The noise is in the subs and the fronts.
I have determined that circuit 3 is "noisier" than 1 & 2 by process of elimination by leaving each circuit out of the mix one at a time. Circuit three has many issues as I followed the wiring but I'm not sure which one to go after first. Here are the issues:
1. I can't fix this one, but this circuit snakes from one upstairs outlet to the downstairs washer/dryer, to outside outlets, and goes underground to power an outside barn/shed.
2. All outlets have been checked for polarity. One is reversed but it's not being used and nothing is plugged into it. Can that still cause issues?
3. Two fluorescent lights are part of the circuit, but they are turned off. Can this be the issue even though they are turned off?
4. One of the outside outlets is a GFCI. I don't even know if this is up to code because it's not even covered. Eventually I'll replace it with a normal covered outlet. Can a GFCI outlet just being on the circuit be the issue?
5. All outlets are old (50 years+) but functioning. Ultimately I'll replace all for safety's sake.
So there it is TLDR assume not cable/coax related ground loop...can unused GFCI in circuit, unused florescent lights in circuit, unused reversed polarity outlet in circuit cause the ground loop?
Thanks for reading and those who respond.
Denon AVR-X4200W / Crown XLI 2500
7.4.4 Klipsch Ref. ii & In-Ceiling Atmos / Titan-615LX center
NU3000DSP - 2 SI HT18 D4's / NU6000DSP - 2 Ultimax 18"s
BenQ W1070 / 120" AT screen / Volt-10LX Atmos build
Last edited by DaleNixon; 03-23-2020 at 01:05 PM.