• Registered: 2018-08-29
  • Posts: 3

Topic: fireface UCX internal Noise below 25Hz

Hello,
I had problem with strange noise bellow 25Hz on all analog inputs.
It's definitly "internal" noise or some digital artifact and it's present at all sample rates.
I try it with USB and firewire connection-the same.

Without any external signal-unpluged jack is level of it aprox -110dB witch is absolutely OK.

But when I plugged some outboard analog gear with little bigger noise floor, the peak of it is up to -75dB.

There is no DC coupling between outboard gear and UCX, I use transformers on input and output.

Its only visible when I set digicheck spectral analyzer filters to 30band-BIQ.

So recorded it. Strange noise is on picture  below 25Hz sine wave for better visualisation.
https://flic.kr/p/2au2FSw

It looks like random interference.
Have anyone similar problem?

thanks

Lukas

  • From: Germany
  • Registered: 2007-04-10
  • Posts: 9,705

Re: fireface UCX internal Noise below 25Hz

What kind of analog"outboard analog gear" is this and what else have you tested?



Regards
Daniel Fuchs
RME

Regards
Daniel Fuchs
RME

RME Support's Website

  • Registered: 2018-08-29
  • Posts: 3

Re: fireface UCX internal Noise below 25Hz

tube buffer with input and output transformer -no DC coupling.

But noise below 25Hz is present even when loop connect in and out on FIREFACE with balanced cable .
Just level is bellow -110dB. But it's look the same and peak the same.

With buffer, noise floor grades a little but the peaks bellow 25Hz are up to aprox -75 dB.

In my DAW it looks like 8Hz or below


thanks

Lukas

4 Reply by lukas.krehel (edited by lukas.krehel 2018-08-29 15:49:49)

  • Registered: 2018-08-29
  • Posts: 3

Re: fireface UCX internal Noise below 25Hz

So I try external converter connected to UCX via ADAT.

Analog inputs of converter are unconnected, gain set to min and also PAD to minimalize noise floor.

Same noise energy bellow 25Hz.

I also try use well filtered external power supply from my lab and results are the same.

thanks

Lukas