Is This A Ground Loop?

[sketterman]

Hello All,

First and foremost - please forgive me. I did do a search...and it netted over 70 pages of results, but I wasn't able to find my issue.

Basically, I'm trying to determine if I'm dealing with a ground loop or not.

Situation: I recently moved my PC to the master bedroom, as it had previously been in our guest room. When I booted up my PC after getting everything connected, I watched a few Youtube videos, and my audio was just fine. Played a mix I created recently, sounded great.

Then I decided to boot up Steam and play some Battlefield. As the game was loading, my monitors both started emitting a really harsh static. Very high-pitched, and it literally drowned out the in-game music and sound effects. So I closed the game, and the static mostly went away. Tried loading another game, and it did the same thing. Loud static from both monitors.

I did a reboot and tried again. Same deal. So it appears to be only with video games. Anything else that has audio seems to be just fine.

Now here is why I *think* it's a ground loop - my sound card is a Scarlett 18i20, connected to the PC via USB. Even with it OFF the speakers do the exact same thing when I open up a game. I even disabled my audio driver in the BIOS. Same thing.

Also...pretty much any time the speakers are on there is a very low static noise. And it changes in pitch when I move my mouse around. This has pretty much always been there. It is noticeably louder now than it has been in the past. Here is the interesting thing: If I unplug the XLR from my left monitor, the static disappears from the right monitor. It still works and will play audio, but it is silent when not playing audio. As soon as I plug the XLR back in, both speakers are static-y. Conversely, if I unplug the XLR from my right monitor, the left monitor continues to be full of static, and it changes pitch when I move the mouse and whatnot.

Everything I use is connected to a single surge protector, and obviously a single outlet. My cables are from Monoprice...I was thinking they might be the issue, but this didn't happen in the other bedroom. They are balanced and shielded.

Anyways, hoping those here with more knowledge and experience than me could offer some suggestions. Thanks for reading,

Shaun

[ef37a]

Hello Shaun and welcome to SoS forum. What you describe sounds very much like the 'classic' ground loop problem (aka hum or earth loop) with earthed computer and earthed active monitors. First thing to say is...

DO NOT REMOVE ANY MAINS SAFETY EARTHS! No matter what you might have read or been told.

I am very certain that a transformer isolator in the XLR feeds to the monitors will fix this issue but there are downsides.
An isolator box such as the Art Cleanbox ll has a good rep but is a bit of money. Transformers also have some impact on sound quality although I doubt you would hear any.

Another approach is to use XLR cables which have had the screen to pin 1 disconnected. Rather than butcher the existing cables I prefer to make up 300mm 'slugs'. XLR to XLR with screen disse'd one end. If you are not up to soldering, buy a pair of the shortest cables you can find and 'mod' those.

e.g. https://www.amazon.co.uk/Premium-XLR-Ma ... 00B28V666/

DOH! Actually you might as well get the cables first anyway Shaun as you will need a second set if you need to get the iso-box. The possible problem with cutting the pin 1 connection is RF interference although this is very rare.

Dave.

[Wonks]

Hi and welcome.

It could be a ground loop, and the video card activity for games is making things much worse.

Or given that you have exactly the same setup as before, and have just moved to a different room, to me it's more likely to be a lack of a ground or a bad mains socket.

Have you got one of those plug-in socket testers? If not I'd get one, and check that the wall socket is wired correctly and not missing a ground or has live and neutral swapped over etc.

And if you are plugging into a different multi-way power distribution block than before, try using the original one, or if the block has a rewireable plug, check that all the wires are connected correctly.

I'd also check any mains leads you are using for a good earth connection if you have a multimeter.

[ef37a]

Hi Wonks, all good stuff of course but I was minded to dive straight into ground loop solutions because Shaun said the 'zipper noise' had always been there.

Dave.

[Wonks]

I read it the background noise is always there after the move.

The devil is in the detail and we always normally work here without full knowledge of the situation.

[sketterman]

Hey guys, thank you for the above replies and feedback. Very much appreciated!

So...I have to admit up front that I'm not terribly versed in wiring. I've also got a relatively modest setup...I don't even know what a 'safety earth' or 'power distribution block' is

For some of the items you guys mentioned that I can speak to:

- Everything I'm currently using is plugged into a surge protector (not sure if we are in different parts of the world where 'surge protector' and 'power distribution block' are interchangeable?). Part of my troubleshooting effort yesterday was to take the two that I was originally using and replace them with a single surge protector. Unfortunately this did not change anything.

- The hiss/hum has *always* been there, regardless of room, or even which home I'm living in. It was preset at all times prior to living in my current home. Now that I'm in this room it is noticeably louder, but still low enough that I don't hear it under most circumstances.

- I do have a plug-in outlet tester...will need to locate it...but I believe it tests that there is current at the outlet...I don't think it tests for a proper ground. I will find it and give it a go though.

Would you guys say it's safe to rule out anything related to the computer and Scarlett? In terms of software, drivers, etc? Since the low hiss and loud video game screeching are present even when the Scarlett is powered off?

Currently, my signal path for the speakers is:

1. PC to Scarlett is the USB cable that came with the Scarlett
2. Scarlett output to Yamaha HS10w subwoofer input is 1/4" to 1/4"
3. HS10w output to Yamaha HS7 monitors is XLR to XLR.

The XLR cables in #3 above have replacements arriving today. The ones I'm using now came from Monoprice and weren't terribly pricy. I'm hoping a nicer set will at least help with the noise. If that doesnt work, I'm going to play around with the cables. Each monitor and the sub can do both 1/4" and XLR for both input and output, so I could swap them around and see if anything nets a better result.

I also routed the surge protector to another wall outlet in the room and the hiss did not change. So two outlets in the same room produce a lot of noise when opening up a game.

I'm going to take the cover off of the outlet here and take a look at the wiring. I'm familiar enough to know what it should look like, maybe something will look out of place. I'll also find my outlet tester and see what happens with that.

Thank you again for the assistance!

*** EDIT to add that I located the outlet tester and it shows all the outlets are wired correctly ***

Shaun

[ef37a]

https://www.amazon.co.uk/Extension-Cabl ... r=8-3&th=1

That ^ is what we mean by a mains power strip, often called "diss boards or diss strips". BTW there is a remote possibility that 'surge protected' strips are causing the ground noise.
When you get your new XLR cables Shaun you can try the pin 1 removal trick*. You say your old cables are of low quality? Won't matter diddley. At line levels and especially with balanced systems cables would almost not to have a screen to give problems and even then maybe not if far from Radio sources. Quality cables are nice to have and will last much longer but no one has ever demonstrated any sonic benefit for cables costing 100 times the ones you have ordered.

Wonks, "Never get the full SP in forums" You can say that again! I have long been of the opinion that posters should at least give their country of residence. In the very rare event that this could compromise their safety (from an ex say!) I am sure our mods would look kindly on an exception.

*Maybe someone can find an illustration? I shall try.

Dave.

Dave.

[sketterman]

Dave,

Gotcha. Pretty sure they are the same thing. I've got one very similar to the 8-outlet version of this one:

https://www.amazon.com/Belkin-8-Outlet- ... 000JE9LCK/

So...if you can believe it, I've actually solved the problem. I was reading up on ground loops, and one option mentioned to fix one to to simply remove the ground from the equation. Then I remembered from time spent in Japan...when I first bought my monitors...and the home I had there didn't have the same plug style...or they didn't have the ground at the outlet...something was different, and in order to use my monitors I needed these:

Link to what is, quite frankly, an extremely dangerous device removed - JP

Luckily I still had a handful. Put one on each monitor and viola, no more hum. Speakers are dead silent when idle. I guess the risk is losing them if we have a huge power surge.

In any case, I'm grateful for the replies. Many thanks!

Shaun

[merlyn]

Here is the interesting thing: If I unplug the XLR from my left monitor, the static disappears from the right monitor. It still works and will play audio, but it is silent when not playing audio. As soon as I plug the XLR back in, both speakers are static-y. Conversely, if I unplug the XLR from my right monitor, the left monitor continues to be full of static, and it changes pitch when I move the mouse and whatnot.

You're saying that the left and right speakers behave differently?

2. Scarlett output to Yamaha HS10w subwoofer input is 1/4" to 1/4"

Is that balanced (TRS) or unbalanced (TS)? A neat explanation would be that the left connection to the sub is unbalanced.

[ef37a]

Dave,

Gotcha. Pretty sure they are the same thing. I've got one very similar to the 8-outlet version of this one:

https://www.amazon.com/Belkin-8-Outlet- ... 000JE9LCK/

So...if you can believe it, I've actually solved the problem. I was reading up on ground loops, and one option mentioned to fix one to to simply remove the ground from the equation. Then I remembered from time spent in Japan...when I first bought my monitors...and the home I had there didn't have the same plug style...or they didn't have the ground at the outlet...something was different, and in order to use my monitors I needed these:

Link to extremely dangerous device removed - JP

Luckily I still had a handful. Put one on each monitor and viola, no more hum. Speakers are dead silent when idle. I guess the risk is losing them if we have a huge power surge.

In any case, I'm grateful for the replies. Many thanks!

Shaun

I am pretty sure what you have done there matey is remove the mains safety ground from the monitors, something I warned against in my first reply!

Now, you are extremely unlikely to get a shock problem with an active monitor but you should NOT do this. However, you have definitely proved you have a ground loop problem so I urge you to try the pin one trick and restore your earths!

Dave.

[sketterman]

You're saying that the left and right speakers behave differently?

Hi Merlyn, you are correct that they behaved differently, which I find bizarre. Also, my 1/4" cables are all TRS.

[sketterman]

I am pretty sure what you have done there matey is remove the mains safety ground from the monitors, something I warned against in my first reply!

Now, you are extremely unlikely to get a shock problem with an active monitor but you should NOT do this. However, you have definitely proved you have a ground loop problem so I urge you to try the pin one trick and restore your earths!

Dave.

Ah, I see now. I guess I'm somewhat familiar with the gear, but not really with the terminology. Looks like I learned something today!

To your point, though, I don't want to leave it as-is. I might pick up an isolator and be done with it.

Thanks again for the support!

Shaun

[Wonks]

Gave you got TRS to TRS cables, or XLR to TRS?

If XLR-TRS, disconnect the ground wire from pin 1 of both XLRs. Snip the wire so that it can’t touch the pin. The cable is still screened because the screen will still be grounded at the other end. I’d mark up the cables to show that the ground’s been lifted

If TRS-TRS, I assume they are moulded plugs. It will be easiest to buy replacement cables with rewireable jacks, and again, cut the braided ground wire connection at one end of each cable, and nark up the cables to say the ground’s been lifted.

Then definitely replace the ground connections on the mains power plugs for the monitors.

[sketterman]

Hi Wonks. I have both, actually. I sort of described them already, but from interface to sub I have TRS to TRS, then from sub to monitors it’s TRS to XLR. And yes, the cable ends are molded.

So I’m understanding:

With the ground part - you cut INTO the cable sleeve to locate the internal wire for the ground, and just snip it? And in doing that, I would no longer need those plug adaptors? Thanks!

Shaun

[ef37a]

Hi Wonks. I have both, actually. I sort of described them already, but from interface to sub I have TRS to TRS, then from sub to monitors it’s TRS to XLR. And yes, the cable ends are molded.

So I’m understanding:

With the ground part - you cut INTO the cable sleeve to locate the internal wire for the ground, and just snip it? And in doing that, I would no longer need those plug adaptors? Thanks!

Shaun

....MOULDED XLRs!?? I suppose there are such horrors but I have never seen any. Even the cheapest ones I have found come apart and allow access to the pins. Pin 1 might also be tied to the shell, if so snip that as well.

N.B. You do this at ONE end of both cables.

Dave.

[Martin Walker]

N.B. You do this at ONE end of both cables.

And when you plug them in, for best results place the clipped end at the far end of the cables (i.e. at the end going into an input socket).

[sketterman]

This is all great info, thank you!

Yeah, molded XLRs. I do have a couple laying around that are removable (and also not long enough for this application), but these particular ones came from monoprice. They were honestly probably 5 bucks for a 10-footer, maybe even less.

FWIW…I’ve been a part of…man…a lot of different forums over the years for many topics…guitars, drums, music production, motorcycles, lots of stuff. I don’t think I can say that I’ve ever gotten this amount and quality of help. Ever. On any topic. Makes me wish I was still into recording and production as I was once upon a time. I honestly came here because I figured this crowd would be best equipped to give me advice. Very glad I did! So again, many thanks. You guys are awesome

Shaun

[Martin Walker]

Thanks for your kind comment Shaun!

We do tend to be a largely happy and helpful community here

[Philbo King]

Perhaps someone mentioned this already...
The first thing to check whether the sample rates or your interface/sound card and Steam match.