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Coil whine on studio speakers

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Coil whine on studio speakers

Postby bobeo » Tue Nov 19, 2019 1:04 pm

Hello!

I wrote it up in points, to make it easier to see through.

Setup: PC -> Scarlett Solo (USB) -> JBL LSR310S (balanced cables) -> JBL LSR305P (balanced cables)


Issue: the GPU's coil whine can be heard through the speakers, especially at high graphical loads. It's the same sound that can be heard I put my ear near the PC case, only it's amplified by the speakers. It changes pitch when moving the wireless mouse, or looking around in games, etc.


Things I've tried, and noticed:

- Tried connecting the speakers to the motherboard's onboard sound card with 3.5mm jack -> -> TRS cable, issue is the same.
- My Razer Kraken 7.1 USB headset does not produce this issue. Tried plugging in the Scarlett to the same USB port, no luck. I noticed the Kraken headset has a ferrite ring near the USB connector. The Scarlett Solo's USB cable doesn't have this.

- I tried plugging everything into the same strip that's in the wall, no luck. (House is about 2 years old, newly built, with an electrician I trust in)

- Tried masking the ground pins of the JBLs' power cords to see if it's a ground loop (as far as I understand this would rule it out), but I had no luck, issue was the same.

- Tried connecting the USB soundcard in every possible USB port, issue was the same. I even plugged it into my screen's USB port, no luck.

- Disabled every sound device I'm not using, unplugged every USB device, disconnected every device I'm not using from the strip. No luck.

Things I haven't tried yet:

Connecting the Scarlett Solo to a laptop, and running it from the battery.


As I wouldn't want to spend a lot of money in equipment that won't solve the issue, I'd like to hear suggestions please. I'm getting super frustrated with it.
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Re: Coil whine on studio speakers

Postby Hugh Robjohns » Tue Nov 19, 2019 2:41 pm

It sounds like a classic ground loop problem to me, so I'm surprised your mains-plug masking thing didn't solve it... although that's not a safe way to do things, of course!

It's most likely a ground-loop between the computer interface and the sub, rather than between the sub and satellite speakers.

If I were troubleshooting this myself, I would insert an ART DTI line transformer isolator box between the interface outputs and subwoofer input, as that would break the ground connection very quickly and easily and prove instantly whether that is the problem or not.

But an ART DTI -- incredibly useful though it is -- will set you back £50 or thereabouts and you mentioned not wanting to spend any money... so I'd try two simple things instead:

First, if you're using balanced cables with XLR plugs at one or both ends, make sure that pin 1 (screen) is not connected to the XLR shell. (It often is in ready-made cables).

This can sometimes cause ground-loop problems in older equipment. It shouldn't be an issue for the JBLs, but it's an easy thing to check and deal with... and it won't make any difference to anything else.

Secondly, I'd try removing the audio cable screen connections from pin 1 at the subwoofer speaker ends of the cable. This is the safe way to remove ground-loops. So open the plug and snip the cable screen back, and then re-insulate and re-assemble.

Again, it shouldn't make any difference to the audio signals at all, but it will remove any ground-loop paths.

Powering everything -- sub, both satellites, interface and computer -- from the same mains board is a wise move. It sometimes cures the problem right away by making sure everything has a common safety earth reference point and minimising the 'loop size', but again, it does no harm either way.

Also, be aware that ground-loops can exist between other equipment, so disconnect all other audio connections from your interface while trying to resolve your speaker noises.

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Re: Coil whine on studio speakers

Postby James Perrett » Tue Nov 19, 2019 9:25 pm

One more check to try - could you plug a standard pair of headphones into the Focusrite with nothing else connected and see if the whine is still there. Does it appear in the headphones if you reconnect the speakers.

One other thing to check - is it really the speakers making this whine? I only ask because I had a strange little whine that only happened when certain windows were displayed. It turned out to be something in the screen making the noise but, as the screen was next to one of my monitors, I thought it was a problem with the audio.
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Re: Coil whine on studio speakers

Postby bobeo » Tue Nov 19, 2019 9:40 pm

James Perrett wrote:One more check to try - could you plug a standard pair of headphones into the Focusrite with nothing else connected and see if the whine is still there. Does it appear in the headphones if you reconnect the speakers.

One other thing to check - is it really the speakers making this whine? I only ask because I had a strange little whine that only happened when certain windows were displayed. It turned out to be something in the screen making the noise but, as the screen was next to one of my monitors, I thought it was a problem with the audio.

I'll plug in my T-Bone headphones that has a TRS jack, into one of the outputs. Hopefully tomorrow after I get home.

You mean to connect the headphones to the left channel, and one of the cables from the speakers to the right channel, and check if the whine appears in the headphones?


It's definitely the speakers, if I up the volume to the maximum on the JBLs, the whine is much louder, so I dial it back 7 notches on each speaker, so it's better.

I mean the whine doesn't get louder with me upping the volume on the Scarlett Solo (in Windows volume is at 100%). At any given setting on the JBLs, the whine is coming at me at the same loudness even when on the Scarlett I set the knob to the lowest possible level. If I set the JBLs to max, it's very, very distractingly loud, 7 notches back, it's still very much there, but at least when there are other sounds coming out, it gets somewhat masked.
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Re: Coil whine on studio speakers

Postby bobeo » Tue Nov 19, 2019 10:30 pm

I'm not sure my post got through, luckily I copied before posting, so here is it again:

Hugh Robjohns wrote:It sounds like a classic ground loop problem to me, so I'm surprised your mains-plug masking thing didn't solve it... although that's not a safe way to do things, of course!

It's most likely a ground-loop between the computer interface and the sub, rather than between the sub and satellite speakers.

If I were troubleshooting this myself, I would insert an ART DTI line transformer isolator box between the interface outputs and subwoofer input, as that would break the ground connection very quickly and easily and prove instantly whether that is the problem or not.

H

Hey, thanks. Especially for the quick approval, and the quick reply. :thumbup:

I'll buy an ART DTI, and a set of cables, I just wouldn't want to spend too much, but it's within my budget. It seems like a better choice than possibly messing up something with my mediocre knowledge and DIY skills.

But just a few questions, how come the USB headset doesn't have this whine then? Because it doesn't have external power?

How is it possible my ground eliminating method didn't work? Is it possible because I used a cheap thin electrical tape that came with a small home use toolbox?

Do I need to worry about the ART DTI breaking the ground connection? Meaning would it be possible to get electrocuted somehow?
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Re: Coil whine on studio speakers

Postby James Perrett » Tue Nov 19, 2019 10:33 pm

bobeo wrote:I'll plug in my T-Bone headphones that has a TRS jack, into one of the outputs. Hopefully tomorrow after I get home.

You mean to connect the headphones to the left channel, and one of the cables from the speakers to the right channel, and check if the whine appears in the headphones?

No - I meant using the headphones on the normal headphone output on the Focusrite. Of course, if you have high impedance headphones you can try them on the line output but I doubt that the T-Bone headphones are high impedance.

It certainly sounds like it is an issue with the JBL's so my first thought would be to disconnect the screen from the balanced cables feeding the JBL's as Hugh suggests.
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Re: Coil whine on studio speakers

Postby bobeo » Tue Nov 19, 2019 10:41 pm

James Perrett wrote:No - I meant using the headphones on the normal headphone output on the Focusrite. Of course, if you have high impedance headphones you can try them on the line output but I doubt that the T-Bone headphones are high impedance.

It certainly sounds like it is an issue with the JBL's so my first thought would be to disconnect the screen from the balanced cables feeding the JBL's as Hugh suggests.

It's a T-Bone hd990d, that's all I know. Honestly, I just noticed the Focusrite has a headphone connection. I'd try it now, but I lended my headphones to my neighbour and I wouldn't want to wake him now. If I get to it, I'll write another post with my findings.
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Re: Coil whine on studio speakers

Postby Hugh Robjohns » Tue Nov 19, 2019 11:52 pm

bobeo wrote:I'll buy an ART DTI, and a set of cables...

Good plan. I have six now because I'm forever lending them to people! :-)

But just a few questions, how come the USB headset doesn't have this whine then? Because it doesn't have external power?

Yes, probably because it doesn't have a mains safety earth conenction, and thus no ground loops.

How is it possible my ground eliminating method didn't work?

Don't know. It could be because the insulting tape got ripped or otherwise didn't do the job right... Did you insulate the earth pin on both satellites and the subwoofer? If not that would be why.

Do I need to worry about the ART DTI breaking the ground connection? Meaning would it be possible to get electrocuted somehow?

No, there is zero risk of electrocution, which is why I'm suggesting you do it. It is the safest solution because it's only breaking the audio screen connection, not the mains safety earth connection!

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Re: Coil whine on studio speakers

Postby bobeo » Thu Nov 21, 2019 4:34 pm

So finally I was able to test with the headphones.

I connected it, and the noise was still there, but then I disconnected the jacks from the rear line out, and voila, the whine was gone.

Is this a clear indication that the ART DTI is going to solve the issue then?
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Re: Coil whine on studio speakers

Postby Hugh Robjohns » Thu Nov 21, 2019 10:08 pm

Clear indications and ground-loops aren't comfortable bedfellows.... ;-) but I'd be reasonable confident it will cure the problem....
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Re: Coil whine on studio speakers

Postby bobeo » Thu Nov 21, 2019 10:46 pm

Hugh Robjohns wrote:Clear indications and ground-loops aren't comfortable bedfellows.... ;-) but I'd be reasonable confident it will cure the problem....

I'll give it a try, fingers crossed. Waiting for the package to arrive. I'll post my results, but it's going to take a few days until it arrives.
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Re: Coil whine on studio speakers

Postby bobeo » Tue Nov 26, 2019 8:53 pm

So the thing arrived, and while it reduced coil whine a LOT, it is still audible in the left speaker that's closer to the PC.

Also I'm not sure if the cables advertised as balanced are truly balanced, as I have a bit of constant static noise now - again, it's loudness is not related to the volume set on the soundcard nor the PC.

I'll try relocating the speakers on Thursday just to see if distance makes any difference.
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Re: Coil whine on studio speakers

Postby Hugh Robjohns » Tue Nov 26, 2019 10:25 pm

Okay, so that's encouraging.

In your system you have multiple potential loops. There's one between the computer and imterface, one between the interface and sub, and another between the sub and the satellites... Clearly, the interface to sub loop was significant. It would be worth experimenting with the sub/sat audio connections to see if they are the cause of your residual noises.

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