Solving a ground loop

[coptician]

Hey all,

Having recently watched Amir's video on ground loops, I understand that a lot of options to try and get rid of ground loops are illegal (though I am in the Netherlands so laws might vary) and dangerous.

I however have a very severe ground loop. My D50S is connected to my iMac via USB and to my Marantz SR7010 via RCA jacks. When I use my PC, a LOT of noise comes through the D50s into the SR7010, showing up both on the amplified outputs and the pre-outs. It's highly related to usage, as the noise shoots up when I do graphically demanding things. It's not subtle either - it's distractingly loud and probably reduces by SNR to 50 dB or less.

I don't know how to solve this. Apparently ground isolators don't work, plus they appear to all be USB 1.1 only which the D50S doesn't like. The SR7010 obviously doesn't have balanced inputs.

So what can I do to solve this?

 

[Chrise36]

Hey all,

Having recently watched Amir's video on ground loops, I understand that a lot of options to try and get rid of ground loops are illegal (though I am in the Netherlands so laws might vary) and dangerous.

I however have a very severe ground loop. My D50S is connected to my iMac via USB and to my Marantz SR7010 via RCA jacks. When I use my PC, a LOT of noise comes through the D50s into the SR7010, showing up both on the amplified outputs and the pre-outs. It's highly related to usage, as the noise shoots up when I do graphically demanding things. It's not subtle either - it's distractingly loud and probably reduces by SNR to 50 dB or less.

I don't know how to solve this. Apparently ground isolators don't work, plus they appear to all be USB 1.1 only which the D50S doesn't like. The SR7010 obviously doesn't have balanced inputs.

So what can I do to solve this?

You can try an xmos usb to spdif converter like the one from douk audio

 

[Speedskater]

Ground loops are about AC mains generated noise. It would be hum & buzz at 50/60 Hz and its harmonics.
I think that you have computer generated noise.

 

[Racheski]

Use the optical in on the D50s instead of the USB input.

 

[mansr]

Hey all,

Having recently watched Amir's video on ground loops, I understand that a lot of options to try and get rid of ground loops are illegal (though I am in the Netherlands so laws might vary) and dangerous.

I however have a very severe ground loop. My D50S is connected to my iMac via USB and to my Marantz SR7010 via RCA jacks. When I use my PC, a LOT of noise comes through the D50s into the SR7010, showing up both on the amplified outputs and the pre-outs. It's highly related to usage, as the noise shoots up when I do graphically demanding things. It's not subtle either - it's distractingly loud and probably reduces by SNR to 50 dB or less.

I don't know how to solve this. Apparently ground isolators don't work, plus they appear to all be USB 1.1 only which the D50S doesn't like. The SR7010 obviously doesn't have balanced inputs.

So what can I do to solve this?

Since the Marantz anyway digitises the RCA inputs, the D50 isn't doing anything useful in that setup. The obvious fix for ground loops here is thus to use an optical input on the Marantz.

FWIW, the Marantz doesn't have a safety ground connection.

 

[mansr]

Ground loops are about AC mains generated noise. It would be hum & buzz at 50/60 Hz and its harmonics.
I think that you have computer generated noise.

Such noise can be, and usually is, coupled through some ground connection.

 

[sergeauckland]

We're getting into semantics, in that noise coupled through the earth connection isn't actually a ground/earth loop, but might as well be one.
I like transformers. They provide proper galvanic isolation.

S

 

[AdamG]

Hey all,

Having recently watched Amir's video on ground loops, I understand that a lot of options to try and get rid of ground loops are illegal (though I am in the Netherlands so laws might vary) and dangerous.

I however have a very severe ground loop. My D50S is connected to my iMac via USB and to my Marantz SR7010 via RCA jacks. When I use my PC, a LOT of noise comes through the D50s into the SR7010, showing up both on the amplified outputs and the pre-outs. It's highly related to usage, as the noise shoots up when I do graphically demanding things. It's not subtle either - it's distractingly loud and probably reduces by SNR to 50 dB or less.

I don't know how to solve this. Apparently ground isolators don't work, plus they appear to all be USB 1.1 only which the D50S doesn't like. The SR7010 obviously doesn't have balanced inputs.

So what can I do to solve this?

Welcome Aboard @coptician.

 

[LearningToSmile]

I have the same issue! Or rather, had until today.

Same deal, PC generates noise whenever my GPU was utilized at all, and it was pretty bad, plus some elevated noise when idle - but only on the RCA-connected speakers. I looked into galvanic isolators before but I think I run into the stupidly expensive iFi Nano iGalvanic or some other audiophile bullcrap so gave up on that idea. Considered some other options, none of them ideal.

Then I searched again without limiting myself to hifi-specific solutions. Turns out you can buy an ADUM3160-based USB isolator for under $20. Limited to full speed USB, not high speed, but should be enough for audio.

Here's the no-name one I bought:

I'm seeing a bunch of similar ones on amazon at varied price points but mostly pretty cheap. You can also buy the naked board with no case. I bet you could also find it on aliexpress for even less.

And it works perfectly for me, the noise is completely gone.

 

[godmax]

Limited to full speed USB, not high speed, but should be enough for audio.

...if USB Audio Class 1 (= 24bits/96 kHz max.) is enough for your use case, than this device will probably do the job. But for UAC2 you will need a high speed capable isolator and these are not so cheap anymore (even non-audiophile ones)

 

[LearningToSmile]

...if USB Audio Class 1 (= 24bits/96 kHz max.) is enough for your use case, than this device will probably do the job. But for UAC2 you will need a high speed capable isolator and these are not so cheap anymore (even non-audiophile ones)

Yep, 24bits/96 kHz is absolutely more than enough for me. I did experiment with some hi-res audio when I got my DAC, and decided I absolutely can't tell a difference.