• Registered: 2023-07-24
  • Posts: 2

Topic: ADI-2 PRO FS R BE: Audible noise from unit on standby

I was plugging in another unit in my audio setup and happened to put my ear close to my ADI-2 PRO FS R and noticed that when on standby, it makes this tiny yet audible noise. The noise is repetitive, like a whirring sound coming from something spinning. I realize there probably isn't anything spinning in the unit, just describing the noise.

And to be clear: I am not talking about noise coming through the analog outputs, but a tiny yet audible noise that you can hear if you're close to the unit. If you turn the unit on, the noise goes away.

This noise is low enough that it is not really bothersome but I wanted to share to learn whether this is normal. Also curious to know what is the source of that noise and why it is only heard on standby.

2 Reply by KaiS (edited by KaiS 2023-09-11 09:21:58)

  • KaiS
  • DAW Mastermind
  • Offline
  • From: Germany
  • Registered: 2020-02-05
  • Posts: 3,126

Re: ADI-2 PRO FS R BE: Audible noise from unit on standby

You can find this kind of sound on most switched mode power supplies.
Press your ear on any of them and likely you will hear it.


It‘s the pulsed charging current, floating through a conductor, creating a pulsing magnetic field.
This field interacts with stuff nearby, “rattling“ it.

There’s one more effect, magnetostriction, (https://en.wikipedia.org/wiki/Magnetostriction) that makes iron change it’s size (very little) in a magnetic field, an effect practically used to build sound transducers.

As switched mode PSU’s usually contain a little transformer and coils with ferrous core, these can act as such.


In standby the PSU pauses some time between bursts of charging, as only few energy is needed.
This creates the mentioned “swirling” sound.

KaiS's Website

  • Registered: 2023-07-24
  • Posts: 2

Re: ADI-2 PRO FS R BE: Audible noise from unit on standby

Thank you very much for the detailed and quick answer. Much appreciated.

Indeed it is the external power supply making this sound and not the unit - I had them side by side and did not realize. I moved the power supply behind the rack and now it is completely inaudible.

Great to understand what the sound is and that it is nothing to worry about.