So I know where my ground loop is... What is the best way to resolve it?

[TLS Guy]

Someone was telling me very confidently elsewhere that as long as one of the three end components was grounded, then it doesn't matter if I lift the grounds to the others. As long as they are interconnected via the HDMI and RCA. If this is true, it would rationalize a more elegant solution.

I could ground the receiver manually with heavy gauge wire, and break the ground (only via the power cable) to both the sub and projector with cheater plugs like loveinthehd and TLS Guy told me about. The projector is then grounded only via the HDMI to the AVR, and the sub is then grounded only via the RCA to the AVR. That way there's no spiderweb of grounds of various resistances, no looping.

But I've been told adamantly by others to never lift the direct ground of a device as more than a test. And while, yes, the RCA and HDMI cables clearly carry ground, I imagine they do so with a higher resistance than the direct path to the wall and may not be suitable for safety. This same person egged me on, saying it's safe, that I know the solution, but am scared to do it. It's true. I may know just enough to be dangerous but I've never dealt with ground issues before, which is why I'm looking for some confirmation or denial of my theories.

Thoughts on that as an alternate solution?

That is true, but it is NOT safe, and against code.

Just one other tip, zip tie the grounding wires to the RCA cable to the sub and the HDMI cable to the projector. That will keep it nice and tidy, especially if the grounding wire is close in color to the other cables.

 

[Titus]

Oh no problem there, my cable management is solid. Thank you for all your help! I ordered a couple things to get the final solution put together. Will be a week before I get everything though.

 

[highfigh]

I don't understand how in one comment you can say it's uncommon for cable providers to not properly ground their feed, and in the next say that it is likely that disconnecting it will make the hum go away. To humor the presumption that this issue is cable related one last time, I have fully disconnected the power and coax from our wifi router which is the only cable provided device in the unit. No surprise to me, it did not resolve the problem.

My photo is 2k pixels wide, you can click on it to blow it up.

I don't know who installed the electrical, I didn't build the place. It is also an apartment.

I don't have a circuit tester but I have a Tripp Lite power conditioner in another room that I checked all outlets with before moving in. It has a light that turns red if it picks up a line fault, and detects a handful of kinds but doesn't specify which has triggered. On one circuit it did detect a fault which was resolved by maintenance changing the breaker. That was resolved weeks ago.

Now I'd really like to focus on the most likely and simplest solution, which is simply that the three components pictured need a mutual grounding point, and how best to achieve that.

WRT "I don't understand how in one comment you can say it's uncommon for cable providers to not properly ground their feed, and in the next say that it is likely that disconnecting it will make the hum go away." - copy & past my comment and the post number- I would never intentionally write that it's uncommon for cable installers to omit the ground connection after all of the installations I have worked on that required improving the ground. If I made that error, I'll edit my post.

The item in the photo is the type of tester I was referring to- they can be found for less than ten bucks. Doesn't need to be that brand, just that type. It's a good thing to have if you have equipment in various locations in the building and it all needs to have common connections, like a router.

 

[highfigh]

There is a metal backplate to the sub, but it appears to be nonconductive because if I touch a couple leads of a multimeter to it to check resistance, I can't get any continuity. Given that the PJ and Sub are already grounded via three prong plugs, couldn't I just run a wire from the receiver chassis to a ground hole on one of the outlets of the power conditioner and then everything would be grounded to the same point? If so, I just wonder if there are any special plugs that allow me to secure the wire to the ground of that outlet.

OK, you have a multi-meter- do you have a test light (the kind with an incandescent bulb, not an LED)? You can use that to find ground loops- disconnect AV cables, attach the clip onto one piece of equipment and touch the tip to another- if the bulb illuminates, you have a ground loop- if it's bright, you have a bad ground loop. To test between the AVR and PJ, you would leave the HDMI cable connected to the PJ and touch the tip or clip to the HDMI cable's shield. This is just for verification, but it's effective.

I had a bad cable TV feed and when I used one hand to disconnect the coax from the cable box with my arm touching the top, I got a pretty strong tingle in my arm. I have seen that many times and it can also cause noise bars to climb up the TV screen.

Your Furman has a grounding post, right? You should be able to use that to ground the other components since it also has a grounded power cord.

 

[Titus]

Final update on everything. All is resolved doing what TLS Guy said, with a slight change. Then I added in a turntable setup on the other side of the room. Here's a new diagram of everything.

The one difference is rather than running the 12 gauge ground wire from the AVR all the way back to the wall outlet and screwing it to the screw on the wall plate, I used this product...

https://www.amazon.com/dp/B07Q1DJVNT

...and a banana plug and grounded it to the Furman. I had more trust in a good connection using this than just trying to get it on that screw, and this way I could keep the wiring hidden because that outlet is out in the open and we want this to be attractive, not just functional. I trust the ground wire in the Furman cable to handle the load in a fault scenario, seems thick and it's designed for up to a 15A supply.

On the right I added in the turntable setup with a long run so it needed to be preamplified first rather than using the AVR's preamp. I did not test it without grounding but I wanted to be sure it had the same ground potential as the AVR setup on the left. The shielding on the RCA alone might have done this, but I just wanted to be absolutely sure there was a low resistance path to the same ground on the turntable so I used another one of the above outlet ground adapters to ground it to the power strip. I suppose technically there could be a loop situation here over that long RCA run, but if electricity only wants to take the lowest resistance option it should not be an issue and everything is dead silent.

 

[TLS Guy]

Final update on everything. All is resolved doing what TLS Guy said, with a slight change. Then I added in a turntable setup on the other side of the room. Here's a new diagram of everything.View attachment 59588
The one difference is rather than running the 12 gauge ground wire from the AVR all the way back to the wall outlet and screwing it to the screw on the wall plate, I used this product...

https://www.amazon.com/dp/B07Q1DJVNT

...and a banana plug and grounded it to the Furman. I had more trust in a good connection using this than just trying to get it on that screw, and this way I could keep the wiring hidden because that outlet is out in the open and we want this to be attractive, not just functional. I trust the ground wire in the Furman cable to handle the load in a fault scenario, seems thick and it's designed for up to a 15A supply.

On the right I added in the turntable setup with a long run so it needed to be preamplified first rather than using the AVR's preamp. I did not test it without grounding but I wanted to be sure it had the same ground potential as the AVR setup on the left. The shielding on the RCA alone might have done this, but I just wanted to be absolutely sure there was a low resistance path to the same ground on the turntable so I used another one of the above outlet ground adapters to ground it to the power strip. I suppose technically there could be a loop situation here over that long RCA run, but if electricity only wants to take the lowest resistance option it should not be an issue and everything is dead silent.

Well done! The point is that you understood the physics of ground loops. So you followed the physics and were successful. It is my hope you stay on this form and become a problem solver. You were correct to amplify the turntable with that long run.

 

[Kleinst]

The Internet cable may still be the problem. Often installers do not install your entry to the home to code. So see if the hum stops after removing all those Ethernet cables. This also applies to any TV cable systems, so disconnect those also.

Just for a test, take out the Furman, and use a power strip. It is just possible it is not a ground loop, but the Furman not able to support the power of the projector, without sending rough power. I personally have a loathing of units like that. There are unnecessary anyway, as the power from the wall does NOT need conditioning. That is absolute bunk. If the hum goes away get rid of it.

If the hum stays then the grounding plan needs changing. The most reliable grounding plan is the "starburst" layout. This is where there is one ground and the other units are grounded back to a central point with stout wire. Remember a ground loop is a resistance between grounds and wires also have resistance.

So, if removing the Furman does not solve the problem, then ground the receiver from the chassis with stout wire via a terminal block at the receiver, and run low resistance grounding wires back to all units to that block.

I have to ground my theater AVP to the metal rack. That is a two prong AC plug. In more complex systems racks are a big advantage and everything bonds to a rack. and then the rack system can be grounded back to the panel. Obviously in most systems that is not possible, but you get the idea.

I'm ignorant on running grounding wires. Is there any risk at all of running a speaker wire as a grounding wire between my receiver grounding post and a screw on my outlaw amplifier? Probably a dumb question but I want to ask before I try. I don't have a significant hum anymore but would enjoy having none. Since it's non audible form where I sit it might be a matter "of don't mess with it"

 

[TLS Guy]

I'm ignorant on running grounding wires. Is there any risk at all of running a speaker wire as a grounding wire between my receiver grounding post and a screw on my outlaw amplifier? Probably a dumb question but I want to ask before I try. I don't have a significant hum anymore but would enjoy having none. Since it's non audible form where I sit it might be a matter "of don't mess with it"

That will not harm anything, but it might make the hum either worse or better. No harm in trying.

 

[Kleinst]

That will not harm anything, but it might make the hum either worse or better. No harm in trying.

Thanks for your reply. I think it might be worth trying just for the heck of it to see if I elminate the hum all together.

 

[Titus]

I'm ignorant on running grounding wires. Is there any risk at all of running a speaker wire as a grounding wire between my receiver grounding post and a screw on my outlaw amplifier? Probably a dumb question but I want to ask before I try. I don't have a significant hum anymore but would enjoy having none. Since it's non audible form where I sit it might be a matter "of don't mess with it"

Looks like the illustrious TLS Guy already got to you but I would add that I don’t think it really matters what the wire is for (speakers, housing circuits, etc) as long as it can be attached and has the resistance necessary. So it could be important to make sure you’re getting OFC speaker wire as opposed to CCA.

 

[Kleinst]

Thanks guys, this is an interesting one. This is in my bedroom setup and I've had a ground loop adventure there. Most all of it was neutered with an isolator I put on my directtv box.

But still a little remained. Somehow it would always go up or down by the center speaker RCA to my AMP. I had a blue jean cable that produced more buzz than I could stand. I put another cable I had gotten free with a purchase and the buzz went down to a very acceptable level. I bought some Monolith RCA's this week because I got some on sale cheap figuring those would be better. Put the monolith on and the buzz went back up to the level of the blue jeans RCA

Damn, what a waste of time. I read about someone grounding their pre pro to their Outlaw 7000x and it worked perfectly and posted here and figured lets try to see if that helps. (My amp is a 7500 not a 7000, different MFG ATI vs. China)

Well, no improvement there but I looked closer at what the "spare" cable I was using was.... Said Black Lab so I looked it up. Seems I have my first Audioquest cable. I instantly recall that this is the company that is for Audiophools. Well, I got to tell you it is the RCA that delivers the quietest signal in a troublesome setup. I had something more valuable than what I was trying to use to replace it. I can't explain how it can be very quiet with the buzz while the others can't but it is.

So I guess I just leave it where it's at and move on.

 

[renardanderson]

I just set up a new home theater and ran into what I believe is a ground loop which I can hear in my subwoofer. The loop is between an ultra short throw projector (grounded), a Denon AV receiver (UNgrounded, connected via hdmi), and a Subwoofer (grounded, connected via shielded RCA cable). All components are plugged into the same Furman power conditioner. When the projector is turned on, the hum starts in the subwoofer. If the HDMI or RCA are unplugged, the hum in the subwoofer goes away. I have tried 3 HDMI cables and 2 RCA cables, all of which have carried the hum but interestingly one longer thinner hdmi cable seemed to attenuate it a bit. When the projector is turned off, the hum stops. If I plug the subwoofer into a different outlet, there is no change. If I plug the subwoofer into an outlet on another circuit, the hum is reduced moderately, but still there.
Showbox jiofi.local.html tplinklogin
Now, what would be the best way to resolve this? I have heard of ground loop isolators I could put inline between the sub and receiver, but I've heard they reduce quality. I also feel that isn't a true solution to the problem, but a bandaid to treat the symptom.

I have also heard of people "lifting" the ground on the subwoofer, which has been firmly discouraged for safety issues. Though to play devils advocate a bit, I have a Klipsch subwoofer in another room that doesn't have a ground prong. If Klipsch doesn't think they have to ground their subs, why should it be so critical that I don't lift the ground on my other one? Especially if it is already connected to a power conditioner.

But I'd assume the best solution would be to ground the receiver. And why don't the Denon receivers I've owned have ground prongs anyway? How would I ground the receiver? The phono input has a ground post, though I am not sure if that can be used to ground the whole system, or just the phono preamp. I also can't find anything conductive on the outside of my subwoofer, other than the outer ring of the RCA interconnects. If I touch some speaker wire, connected on one end to the phono grounding post on the receiver, to any of those additional interconnects while the LFE is connected, I hear an ever so slight reduction of hum but it is clearly not doing anything useful to resolve the ground loop.

Of these solutions, which would you suggest, and why? Include some details on the "how" if applicable. Thank you!

Note: I know this is not an issue with just my receiver unit. I have tested with two of the same model from the same brand, both brand new. The first did have some unrelated issues that justified a free replacement, which is why I was able to try with two.

if you have cable or satellite those can be the cause when not properly grounded.

 

[highfigh]

Someone was telling me very confidently elsewhere that as long as one of the three end components was grounded, then it doesn't matter if I lift the grounds to the others. As long as they are interconnected via the HDMI and RCA. If this is true, it would rationalize a more elegant solution.

I could ground the receiver manually with heavy gauge wire, and break the ground (only via the power cable) to both the sub and projector with cheater plugs like loveinthehd and TLS Guy told me about. The projector is then grounded only via the HDMI to the AVR, and the sub is then grounded only via the RCA to the AVR. That way there's no spiderweb of grounds of various resistances, no looping.

But I've been told adamantly by others to never lift the direct ground of a device as more than a test. And while, yes, the RCA and HDMI cables clearly carry ground, I imagine they do so with a higher resistance than the direct path to the wall and may not be suitable for safety. This same person egged me on, saying it's safe, that I know the solution, but am scared to do it. It's true. I may know just enough to be dangerous but I've never dealt with ground issues before, which is why I'm looking for some confirmation or denial of my theories.

Thoughts on that as an alternate solution?

You can lift a ground, but not if it's a safety ground, as in, the power supply needs it to prevent some part of the device becoming electrically 'hot'. A turntable or most source devices are in that group but amplifiers aren't. AVRs and most receivers don't use a grounded power cord but it the cord that was supplied with the device has a ground pin, it's supposed to be grounded.

 

[Astec]

I’ve been looking at ground loops recently and came across this thread. I would suggest that the culprit here is the “ground” connection between the JVC projector HDMI and receiver HDMI. We all assume the HDMI cable’s shielding will be at the same ground as the earth of both pieces of equipment - but it may not be. I found this in my setup, but with a TV instead of a PJ.
I fixed it by re-purposing an old HDMI cable that had a DVI connector on the other end, which I cut off, stripped back to expose enough of the shielding in order to twist it and then wrap it around the fixing screw of the earth of a power plug. When I connect this HDMI cable into an unused port on the TV (in your case the PJ) and the power plug into the common powerboard, the hum/noise completely disappeared.

 

[DJWPAR3]

Not certain where to post tis, but on a similar issue....1 time a session(tv,movies, youtubetv etc) there will at sometime be a loud pop!...Loud enough to make anyone in the room recoil....than it wont happen again.
YAMAHA 2080, SVS towers, center, yamaha ceiling(6), svs 3000 sub.
USUALLY happens during broadcast TV....any ideas? similar experience.

THANK YOU

 

[everettT]

Not certain where to post tis, but on a similar issue....1 time a session(tv,movies, youtubetv etc) there will at sometime be a loud pop!...Loud enough to make anyone in the room recoil....than it wont happen again.
YAMAHA 2080, SVS towers, center, yamaha ceiling(6), svs 3000 sub.
USUALLY happens during broadcast TV....any ideas? similar experience.

THANK YOU

If it happens while watching CBS, ive had issues with loud artifacts, like crackling and popping, it's happened across 4 different different providers, so it's their mixing.

In sounds different in your case so you would need to isolate whether it's from the speakers or the subwoofer to figure out which amplifier is causing it, the Yamaha or SVS.

 

[DJWPAR3]

I had assumed it was the broadcaster, but will look into sub as the "artifact" IS low frequency.
Frustrating....and try explaining it to the WIFE!

 

[everettT]

I had assumed it was the broadcaster, but will look into sub as the "artifact" IS low frequency.
Frustrating....and try explaining it to the WIFE!

It has been annoying. Watch any of the FBI CBS shows after the opening scene when they flash "FBI" it happens and anytime where there is explosion. I've tried everything.

 

[highfigh]

Thanks for your reply. I mentioned in my reply to everettT just now that I do have an ungrounded wifi router in the entertainment center, but why I don't believe it would be related to this issue. I would prefer not to resort to lifting ground, but am still curious as to why one of my subwoofers is apparently safe to not ground by design, but another isn't.

What is an "ungrounded WiFi router"? Is it a repeater, is it hard wired to a modem? If it's connected to anything by using an ethernet cable, it's grounded.

If that piece was the cause of the ground loop, it wouldn't require the projector to turn on- you would hear it anyway.

DO NOT lift grounds, separate equipment. You could try using a wireless transmitter & receiver for the sub- if that connection causes hum, the wireless setup can cure it.

Why are you mixing & matching subwoofers?

 

[highfigh]

Not certain where to post tis, but on a similar issue....1 time a session(tv,movies, youtubetv etc) there will at sometime be a loud pop!...Loud enough to make anyone in the room recoil....than it wont happen again.
YAMAHA 2080, SVS towers, center, yamaha ceiling(6), svs 3000 sub.
USUALLY happens during broadcast TV....any ideas? similar experience.

THANK YOU

Your system may be on two circuits with one having the Hot & Neutral reversed. I have heard that kind of sound with a guitar amp and delay effect that had a grounded power cord.

Use a tester like I posted on pg 1 to test all of the outlets used by the system.