Help with some nasty USB computer noise

MikeSattler · 1320

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Offline MikeSattler

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on: March 10, 2020, 11:57:23 AM
Hi everyone! So I've had this issue with my Crack after using it with a new PC build and any help would be greatly appreciated.

I have my PC connected via USB to a Chord Mojo, which is connected via RCA to the Crack. The issue is that every time the computer ramps up, whether its running a 3D game or some other intensive task, I get a blast of digital noise in my headphones. The sound changes as the computer does various tasks (opening software, going from a game loading screen into an online match, etc...). Disconnecting the USB cable completely eliminates the noise.

Now here's the weird thing, one would expect that this noise would be present in the Chord Mojo as well since it's feeding signal to the Crack. However, when I plug my headphones directly into the Mojo, it's dead silent. So the issue is isolated to the RCA interconnect and the Crack.

I've tried 3 different RCA cables and none have made a difference, so I don''t think thats the issue. The next thing I tried was moving the Crack as far away from the PC as possible (about 8 feet) which made no difference either. I also tried using a different solid state amp instead of the Crack and it's dead silent. So it looks like it's solely the Crack picking up the USB noise somehow.

I don't think it's a grounding issue either because the PC, Crack, monitors, everything is plugged into the same power strip. At this point I'm at a loss for what to do. I know an optical output from the PC would be ideal but unfortunately this motherboard doesn't have one. Any thoughts on a fix?



Offline Thermioniclife

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Reply #1 on: March 10, 2020, 12:24:53 PM

Lee R.


Offline kgoss

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Reply #2 on: March 10, 2020, 12:35:12 PM
Also try plugging the Moho and Crack into another outlet. Or at least another power strip not powered by the same one powering the computer.

Ken Goss


Offline Deluk

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Reply #3 on: March 12, 2020, 01:47:54 AM
What result do you get if you run the cable direct from your PC to the Crack? i.e. omit the Mojo.



Deke609

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Reply #4 on: March 12, 2020, 06:46:32 AM
I have my PC connected via USB to a Chord Mojo,

Just a shot in the dark here. IIRC, the Mojo has two possible USB-PC connections - one for power, and one for signal. Have you tried running the Mojo on its battery power and only connecting it to your PC for signal? I wonder whether the PC is polluting the USB DC power-out with noise and that noise is getting added to the signal-out of the Mojo.

cheers, Derek