Help needed with (probably) ground loop issue.

RonnieNine

Honorable
Mar 17, 2013
6
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10,510
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Hello all,

I get a high-pitched whining noise whenever I pair my PC with other audio equipment having a separate (built-in) power supply.

The noise is significantly louder when scrolling, switching pages, clicking, opening programs.

Using line-in to link PC soundcard with HIFI Amp: noise
Using USB to connect PC to External soundcard and THEN linking the external soundcard with studio monitors: noise
Linking the internal soundcard with a 12Channel Mixer: noise
Linking the USB External soundcard with the mixer: noise.

Whenever using headphones (so they are not powered by any external power supplies) with any of the soundcards, there is no noise unless I link the PC with any of the equipment mentioned above. That being said, I don't even need to use nor power on the equipment and can still hear the noise in ALL of the channels.

I tried the following:
- plugged them all into separate and same outlet/power strip.
- unplugged everything, unless its something to do with the PC, there is no noise.

- used a jack cable and touched PC case: noise everywhere except when touching the power supply with the jack.

If I knew that a power conditioner will fix my problem, I would get one.

 

jasonkaler

Distinguished
Nov 22, 2011
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18,610
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unfortunately this problem stems from different power supplies working differently and there being a voltage difference between their two ground levels.

It's quite common for an amplifier to have a power rail that is below 0v, and that difference to the pc's 0v is where the buzz comes from. Even a power conditioner or power strip with isolators may not help in that case.

One potential solution is to run a wire from the one power supplie's ground to the other i.e. a common ground, but I would not recommend this to the average person who's not qualified to work on electrical equipment as it could cause a fire, death etc.

Another possible solution is to convert the signal to digital as the problem is routed in the signal being analog.
Or possibly try something like this:
https://www.amazon.com/Mpow-Ground-Isolator-Stereo-System/dp/B019393MV2

What exactly is the noise you're hearing? Is it like tv static, a buzz, a hum?
Sometimes a ferrite bead on the cable helps (Those round things you often see near the ends of keyboard or monitor cables). They're there to reduce interference, is that's what the noise is.
 

RonnieNine

Honorable
Mar 17, 2013
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10,510
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Thank you for your answer.

Somehow merging the two grounding cables sounds like a good idea to me. I am not used to work with high voltage or anything similar, so I'll ask a friend, who's an electrician.

I can't convert it to Digital though, best I could do is use balanced in/outputs (XLR), but that would (MAYBE) only fix the monitors.

The noise has two layers:
1. A static hum (like the 60Hz hum, or how a big transformator sounds at a power plant) and this is being quiet.
2. A medium high pitched whine, like 2000Hz or so.
 

sirius360

Prominent
Nov 2, 2017
1
0
510
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Hey RonnieNine

I have the exact same problem. My groundloop sound is exactly 2000hz. I can even hear it when i get very close to my computer, i think it comes from the cpu or mainboard, ram.. (no hard disc or cd reader)

Do you have any solutions? I hope you can help me out!

Greetings
 
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