Help me get rid of the groundloop in my config. (pic rel)

[JackTylerDurden]

After connecting the headphone amplifier, the groundloop appeared. It's for sure groundloop casue after connecting amp to power strip without ground bolt nosies disappeared. I would like to advise you how to get rid of the ground loop in the configuration I attach (pic rel.).

My ideas are:

add a filter on the usb cable (I would not like to do it)
connect the interface to the amplifier with balanced TRS -> XLR cables

Please help.

 

[antcollinet]

Best would be optical from pc to motu if available or can be added. If not then usb to optical devece, or usb isolator device. Failing that, route all the wires (mains, rca, usb, pc mains) close together inline. (Not looped or coiled) back to the mains strip! And as far away from interference sources as possible, especially pc, monitor and monitor cables.

 

[MCH]

Unfortunately the Motu does not have any optical I/o
But his headphone amp does have balanced inputs, and the Motu has balanced outputs, so why not trying connecting motu and headphone amp through balanced instead of RCA?
Additional benefit a couple more volts to blow your ears if wanted.

 

[JackTylerDurden]

@tonycollinet Thanks for the tips I'll try all your hints.

@MarcosCh You r right and that is one of my ideas I listed above. I bought such cables and I will try such connection in couple of days (hope it helps).

 

[ppataki]

I bought such cables and I will try such connection in couple of days (hope it helps).

That must help - if not you can try this: http://archimago.blogspot.com/2022/03/measurements-topping-hs01-usb-20.html

 

[JackTylerDurden]

Wow, I just checked the review of SP200 to find out if it is really balanced, and look what I found:

My favorite, XLR inputs are included which can be of a great help in avoiding ground loops with your PC and DAC.

so, now I have even more confidence that adding balanced cables will work.

 

[Dunring]

I have that amplifier and with RCA on a song at high volume there's a hiss if the DAC doesn't have a power supply of its own for ground, on XLR it's always silent.
If you have an extension cord to test it on a different outlet it might be a quick way to test. Going to XLR is a really good idea with the SP200 though.

 

[JackTylerDurden]

I have that amplifier and with RCA on a song at high volume there's a hiss if the DAC doesn't have a power supply of its own for ground, on XLR it's always silent.
If you have an extension cord to test it on a different outlet it might be a quick way to test. Going to XLR is a really good idea with the SP200 though.

I've already tested it removing ground for both power ends (connecting smsl without ground bolt and connecting motu interface to not pluged laptop) in both cases noises dissapeared. That's why I'm pretty much sure that this is groundloop.

Your case proves that balanced interconects will help.

 

[antcollinet]

If you have the choice of balanced connections that should fix it.

 

[jasonhanjk]

Get an amp that uses secondary AC input, example NwAvGuy's O2 amp.

 

[Recluse-Animator]

Try some 75 Ohm coaxial RCA cables.

 

[JackTylerDurden]

Confirmed. Noise, buzzing completely disappeared after adding balanced cables connecting amplifier and interface. Thanks for your help and guidance.