• Registered: 2023-09-08
  • Posts: 1

Topic: USB leaking noise to GND

Hello good people

I am an RME FireFace UCX II user and a few weeks ago I connected an old Roland analog mixer (M24-E) from the master out (+4dBm) with XLR cables to TRS inputs in the UCX II.

After finally getting to recording and monitoring the mix at the mixer and on the UCX II I have a faint high pitch whine that is driving me crazy.

As I understand correct, this must be the computer ground polluting my analog ground over USB, all the way to my mixer. I can hear HDD noises in my mixer. When I plug out the USB cable of the UCX the noise goes away completely.

After a lot of research and before purchasing an expensive Intona USB isolator or a stereo DI box with GND lift. I wanted to ask if there is another solution to the problem I am having or something I can try. It is a hefty purchase for me and wanted to ask what the best model of USB isolator would be best for my needs to not sacrifice in sound/speed.

I am very acquainted with electronics and understand ground loops but wanted to ask here first for other ideas or is it best to give up on this old Roland console.

The Roland mixer has a two prong plug so it is not connected to the earth at the power plug and takes ground from the balanced XLR cables to the RME.

Hope to receive some advice that helps me solve this issue.

2 Reply by sbcrikey (edited by sbcrikey 2023-09-08 22:00:47)

  • Registered: 2021-12-30
  • Posts: 151

Re: USB leaking noise to GND

in the past, when I was tracking down HDD noise and ground loops, I took several feet of speaker wire and attached one end to a case screw (ground) and went around touching the other end to each audio device chassis hooked up to my sound card (tape deck, digital piano, etc.) when the noise got quiet or disappeared, then I got some solid copper wire with terminal spades and made them permanent. this was a long time ago on a very old PC but it helped tremendously.

also, would you be able to try out the UCXII on a laptop running on battery? there are many tests you can try to isolate the problem.

good luck smile

  • Kubrak
  • DAW Mastermind
  • Offline
  • Registered: 2023-08-03
  • Posts: 541

Re: USB leaking noise to GND

Kenny S. even 2 wire plug creates ground loop. One of those two is ground. I do not recomend that, but you may proove it by touching the wires, one makes nothing, the other bites you. ;-)

Do you have all gear plugged to a single wall outlet? If not the grounds from different outlet may be different, they should not be, but I have experienced even more than 100 V difference on grounds of two different outlets in one room. It was older building...