ground loop buzz - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 5 Old 05-15-2019, 12:59 AM - Thread Starter
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ground loop buzz

Ok guys, I have what I think is a ground loop issue of some sort. What's happening is that I'm getting a buzz in my speakers (not my subs from what I can tell). This system has 5 SEOS high sensitivity drivers in them so I assumed at first it was just ground floor noise that they were picking up as you couldn't hear the buzz unless you were on top of the speakers. Now the buzz has intensified to where I can hear it at quiet points in a movie (meaning it's gotten louder). it's not a hum, not a crackle, but a distinct "buzz" that rises and lowers it's volume depending on the volume of the receiver

I've been troubleshooting the last 24 hours like a madman and THOUGHT I had it fixed, but now I'm not sure what is the actual cause as several things seem to get rid of it.

First I thought it was my Peavey IPR amp for my passive subs as that can be a typical issue. Well, unplug the sub (or any link from the sub to the receiver, such as disconnecting the mini-dsp in between, pulling the rca cable connecting the minidsp to the amp, or pulling the sup cables from the xlr ports on the back). I found that bypassing the minidsp didn't change anything, as plugging the xlr to rca cables from the amp directly into the receiver introduced the speaker buzz again. I change the plug over to another circuit in the house and it fixes the hum. HOWEVER, that circuit of the house is older and doesn't having a grounding plug, so I'm not wild about there. Plugging the peavey amp into another outlet on the circuit doesn't change it either.

now here's the kicker. I thought I had found it with the amp, but when I turned off my Blu-ray player.... BOOOOM. Instantly the buzz went away. getting puzzled I looked into it. Even with the sub plugged in and going, if I disconnected the Blu-ray player from the receiver (from the HDMI cord, or just powering it down and off) the buzz would go away. At first I thought I just had a crummily shielded HDMI cable or power cable so I swapped out the HDMI cable and plugged the player into another outlet. still the same thing. Then I started playing around. The buzz goes away IF I change the HDMI input on the receiver (say I have the player plugged into HDMI input 2. if I change to HDMI Input 3 on the receiver, and the player and sub are still going, the buzz vanishes. same with 1, 4 and 5, but If I got back to the active HDMI 2 with the Blu-ray player on and the peavey plugged in, then the buzz starts up again. muting knocks the buzz off, as does lowering the volume to zero.

Thinking I had a bad port I started moving the player over to other HDMI inputs (1, 3, 4 and 5) and the buzz follows once you change the receiver over to those inputs. Then I tried something else. I pulled my Redmere HDMI cable from the back of the receiver and BOOM... instantly went away. plugged it into my BR player and of course it had no buzzes (the hdmi from the player to the receiver was unplugged so of course it didn't). my BR player doesn't have dual HDMI outputs otherwise I'd check to plug the projector cable into the player and run a separate out to the receiver for audio to see if that fixes it, but no dice there.

Now I'm scratching my head. if only one thing affected the buzz then it would be easy to nail down. A faulty ground loop with the sub amp and call it a day. But it's the other 3 things affecting the buzz when amp is plugged in that makes me wonder if there's more to it. Unplugging the projector's redmere cable does the trick, unplugging the amp (or it's connection from the amp to the receiver) does the trick, unplugging the Blu-ray player does the trick (the hdmi or powering down, as if it's powered up AND connected with the HDMI cable to the receiver then it insantly starts static) etc. With multiple things affecting it I'm literally at my wits end trying to figure out WHAT is the cause!

1. Is it my amp?
2. Is it the redmere active HDMI cable going bad and causing interference?
3. Multiple players were tested and all exhibit the same thing when turned on and connected to the receiver
4. Is it my receiver going belly up?
5 other options that my crazy mind can't think up.

at this point I could start switching out half the components in my room trying to nail it down so I've gotten more and more confused as troubleshooting only shows MORE options it could be instead of isolating

Last edited by wormraper; 05-16-2019 at 12:44 AM.
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post #2 of 5 Old 05-16-2019, 12:44 AM - Thread Starter
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thought I had fixed it. guess not. updated the post after I've troubleshot the crap out of it. any ideas?
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post #3 of 5 Old 05-16-2019, 04:46 AM
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I had a similar issue only happened when I turned on the inuke amp, I attached a ground wire on a case screw from the amp to the avr and then to the bluray player and that seemed to fix it for me
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post #4 of 5 Old 05-16-2019, 05:25 AM
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We have a wifi printer in another room which causes a slight hum (occasionally...seems when its sleeping) in my amp's transformer.....when doing serious music listening or BD/streaming/TV, I just shut the printer off.....

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post #5 of 5 Old 05-16-2019, 07:42 PM - Thread Starter
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Quote:
Originally Posted by Brian18 View Post
I had a similar issue only happened when I turned on the inuke amp, I attached a ground wire on a case screw from the amp to the avr and then to the bluray player and that seemed to fix it for me
actually, that's not a bad idea. attach a piece of wire from the receiver to the amp or the Br-player's chassis and see if that affects it at all.

I double checked my grounding on the outlets to make sure I wasn't getting a faulty ground in my wiring, but everything came out fine, so I'm guessing it's equipment related. I'm hoping it's not the older Redmere cable, as someone on a different forum said they were notorious for causing isssues (mine is 2014 aged) and active cables were the only way I could get a 50 foot run without spending buku bucks or getting a repeater

another thing. If I have the receiver OFF when I turn on the audio system it's fine also. It's when I have the amp plugged in, the receiver on, the BR-player on, AND the projector on at once that this comes into play. turn off or unplug any one of these (except the peavey amp, if it's just plugged in and the other stuff is on the buzz will come into play)

Last edited by wormraper; 05-16-2019 at 07:45 PM.
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