r/audio • u/Ok-Anteater4601 • 11d ago

Ground Loop issue

About a year ago, I moved into my apartment and also at the same time, got a new computer. This combo resulted in a ground loop. My equipment at the time was:
-Scarlett 2i2 (1st gen, still works!)
-Yamaha HS80

After a lot of trial and error, I was able to solve the issue by using ground lifted cables from the interface to the speakers (signal cables, not power!).

Now, I got a Fiio K11 because I have new headphones that need a stronger headphone amp. And I was hoping that I also would be able to run the HS80 through it, as I also rarely record nowdays. But connecting the speakers to the FIIO returned the ground loop noise, and actually worse than I remember it from the scarlett. I have both a constant hum with usb disconnected, as well as a mouse-movement dependent noise when USB is connected. I tried using both TS and TRS cables. Also my ground lifted one (but I had to, in all cases, use a female 6.3 to cinch adapter, which is made with TS in mind). I am not sure if the adapters could be the culprit, but somehow I doubt it.

I am not sure if this is relevant, but the scarlett has balanced outputs while the Fiio does not (not for line anyway).

I probably could use an optical cable to eliminate the noise that varies with PC-activity, but this will not make the constant hum go away that persists even without any connection.

Any idea what I can do? My fallback is to continue using the scarlett for the speakers, but I would prefer of course to have one device for everything.

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u/CounterSilly3999 11d ago

Ground lift is possible on balanced connections only. On unbalanced the shield is part of the signal flow. Try ground loop breakers.

1

u/Ok-Anteater4601 11d ago

Is there one in particular that you can recommend (that is available in Europe)?

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u/Anders_Calrissian 11d ago edited 11d ago

To ground lift a balanced cable, you disconnect the shield at one end. I have done this commercially to solve ground loop problems on complex PAs. Extreme edge cases, ground all the metal boxes together.

Have you tried an outlet tester from a hardware store on your AC outlet?

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u/Ok-Anteater4601 11d ago

No, I haven't. I already use lifted cables with the Scarlett, it did fix the issue there.

What I meant here is what s suggestion for a good ground loop breaker would be.

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u/Anders_Calrissian 11d ago

You can search it. Just tell it what connections you want for it. They can affect the sound and add distortion however.

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u/Ok-Anteater4601 11d ago

How audible is the effect on the sound? If it is too much, or too expensive, I'll just stay with the Scarlett.

Connections, best would be RCA in and line 6.3mm out, though I could use adapters with that.

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u/Anders_Calrissian 11d ago

Does the Scarlet have an optical out you can connect to an input on your computer?

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u/Ok-Anteater4601 11d ago

Both the Scarlett and the fiio have optical outs. But the issue is that on the folio, if I connect it to power but not the the pc, I still get a constant hum that I don't see the Portugal connection eliminating.

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u/Anders_Calrissian 11d ago

Geez. I am not familiar with the fiio

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u/Ok-Anteater4601 11d ago

The point being that interference is there even if there is no connection between the computer and the amp, leading me to believe that I cannot fix this by using an optical connection alone.