Strange Ground Loop Problem... I Guess?

Mitsakes

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Apr 6, 2017
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I hope this is the right place to ask, and I am not quite sure where to start in describing this problem. I have had it for several years now, and tried unsuccessfully to solve it. I am experiencing some really infuriating digital interference noise from the headphone jack on my audio interface that changes pitch and intensity based on what kind of load my computer has. More specifically, I feel like the pitch of the noise is directly related to how bright or dark the screen is. Its really only noticeable in games, and even then it isn't always there (which makes it especially difficult to troubleshoot). This noise has been here through multiple graphics cards, multiple USB audio interfaces, regardless of whatever additional USB devices are plugged in, and no fewer than 3 homes. First off, some specs:

Windows 7 64bit
XFX PRO850W XXX
AMD FX-4300
Gigabyte GA-990FXA-UD3 Rev 4
Nvidia GTX 950 FTW
Mackie BlackJack Onyx USB

All of the research I have done has been pointing to the idea that this is a ground loop issue. Apparently, that can be caused by some shoddy electrical work but seeing as I have now lived in 3 different places and the problem exists in all of them, I don't find it likely that bad electricity is the cause.

A big question I have is whether or not my PSU or motherboard (The two components that haven't been replaced) could be behind this issue. Based on the fact that it appears only in games and changes based on what is being displayed on my screen, one might think its a GPU problem too. Again, I've switched from AMD to NVIDIA and this problem still persists. I have been thinking about switching to Intel because I had a similar problem with my Zoom H4N sounding crazily distorted when going through USB. I found out that AMD has issues with that device and I bought a PCIE USB card to solve the problem. It worked, so I got my hopes up that it might help this ground loop problem too, but it didn't. However I am afraid that if I switch to Intel, the problem my persist because the PSU is causing it. Similarly, dishing out for a new PSU would be a shame if it is an AMD problem. Whatever the problem, it definitely manifests itself through USB. My internal sound is fine.

Something else to note is that it only affects the headphone jack on USB audio interfaces (unfortunately can't test firewire with my current setup). Turning up the headphone gain doesn't make it any louder either. My monitor outputs are not affected whatsoever. Maybe thats something to do with the TRS cables, no clue.

Anyways, sorry for the wall-o-text, but I figured I better throw brevity out the window with a problem like this. Lately I have been updating all my drivers/bios and I haven't hear the problem yet. But again, it only crops up occasionally so I thought I would post this in the meantime. If anyone's willing to offer some advice, thank you!
 

the nerd 389

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Nov 20, 2012
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Can you post a recording of it? You can probably record it using the stereo mix recording device.

Also, it's probably not a ground loop. Those are really rare in practice, and lots of people incorrectly attribute many unidentified issues to 'ground loops'. As a rule of thumb, you may run into ground loops if you're powering your audio system from two separate buildings or a single, very large building with power connections at the far ends.
 

Mitsakes

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Well thats the thing, its not present on any of my meters. All of my software outputs are clean as a whistle but it comes through on the headphone jack on USB audio interfaces. Really I think it must be coming from some USB problem, because the sound gets interrupted or distorted even more when I move my mouse. Again, i've already tried unplugging all the USB devices I use and yet it somehow still keeps whining away. The best I can describe is it being a high pitched whine that changes pitch slightly after certain actions or under certain conditions. The tone also gets broken up into a much quieter noise when I move my mouse or hold down a key on my keyboard. It also just cuts out intermittently for seemingly no reason... hmm maybe related to hard drives spinning up? Ill test that theory out tomorrow, and maybe see if I can mic up my headphones so you can hear what I mean.
 

the nerd 389

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My first guess is that there's a power quality problem. USB audio devices tend to let power supply noise through to the outputs. The problem usually comes from the PSU, and if the USB device doesn't take steps to protect against this kind of noise, you will be able to hear it.

Whether or not it shows up in the software output depends where in the circuit the noise enters from.

Try a USB hub with it's own power connector (wall wart), and only connect the audio device through it. That can fix the issue in many cases.
 

the nerd 389

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Use this approach at your own risk. Some USB DACs will power the digital side with USB power, and the analog side with external power when it is available. This approach is actually the most resilient to USB power quality issues when properly implemented, and is usually used in well-thought-out designs.

That said, he is correct in that if you have the option of using an external power supply, you should.
 

Mitsakes

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I remember thinking about looking for a hub that wasn't powered through USB awhile back, but I got discouraged when my PCIE USB 3.0 expansion card didn't do anything to the problem. However, it makes sense that if it really is a PSU power issue, then anything connected to the PSU (be it through USB or PCIE) will be getting some dirt. I'll see if I can get ahold of a cheap hub with power adapter to test your theory, it sounds promising. Thanks for the help!
 

Mitsakes

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Unfortunately the Onyx Blackjack doesn't have a separate power supply, but thanks for the info regardless!
 

Mitsakes

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Alright, so I got an outlet-powered USB hub but the problem still remains. Ive tried plugging it into different outlets and they all act the same. Maybe the hub is still pulling power through USB even though it is plugged into the wall? Not really sure what to think at this point, but these findings might suggest it isn't a power issue.
Here is the device I bought: https://goo.gl/JoozIx
 

Mitsakes

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Oddly enough the noise seems to go away completely when I run the GPU stress test in FurMark! Once again, not sure what to think of that. I have went through two video cards with the problem persisting, both AMD and Nvidia. Wow this is crazy, and I'm just realizing it now, but when I have a text box active and the text bar is flashing, I can hear the sound pulse with the rhythm of the bar. Basically when the black insertion bar appears, I hear a short noise, followed by another when it disappears, and the cycle repeats. Again, typing also seems to interrupt the noise. What in the world is going on here...
 
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