1 (edited by cjunekim 2021-09-12 19:56:53)

Topic: Why crosstalk from playback to analog mic input?

Hello.

I am using UCX(along with several more rme products). I recently noticed there was a strange crosstalk.

I use phantom power to trs plug-in power(5v bias) adaptors, for example, VXLR+ and D-XLR.

https://www.rode.com/accessories/vxlrplus
https://deitymic.com/d-xlr/

Both work fine but there is some crosstalk. If I connect the adaptors to the analog xlr input 1 and connect nothing to their trs jack(hence no input), and play any sound from computer through playback 1/2 and to a headphone output, the playback sound bleeds into the analogue mic input. The analogue mic input gain is at 33db and noise floor is at around -85dbfs(peak) but when music is playing the noise floor suddenly jumps into -50dbfs. It's 35db's difference and it's huge, I think. This doesn't seem to happen when an xlr cable is connected to the same input without connecting it into anything.

Why would this happen and what can I do to lower the noise floor when using such an adaptor?

2

Re: Why crosstalk from playback to analog mic input?

Does that also happen when the mic is connected to the adapters?

Regards
Matthias Carstens
RME

Re: Why crosstalk from playback to analog mic input?

MC wrote:

Does that also happen when the mic is connected to the adapters?

Yes, it does, whether or not the mic is connected.

4

Re: Why crosstalk from playback to analog mic input?

I can't explain it, sorry. What you hear is RMS (change the level meter to see those numbers), so it might not be as bad as it looks like.

Regards
Matthias Carstens
RME

5 (edited by cjunekim 2021-09-13 06:48:50)

Re: Why crosstalk from playback to analog mic input?

This is truly interesting.

Today I found that this crosstalk happens only when the headphone is connected to the headphone jack on the front panel. If there is nothing connected to the headphone jack(or the headphone output fader from totalmixfx is at minimum), this crosstalk doesn't happen at all. I am still talking about the setting when microphone is not connected to the analogue 1 input, but just the xlr to trs adaptor only. Moreover, what's stranger is, if I put a load on the headphone jack via something like ifi IEMatch https://ifi-audio.com/products/iematch/ (I use this to level match) without any headphone, the noise level goes up as well. I believe something has to do with the load on the headphone output.

I recorded the bleed from the analogue input 1 with gain at maximum. I am playing MJ's "Remember the Time" from the UCX playback 1/2. You can clearly hear the song from this recording among background hiss.

https://drive.google.com/file/d/1tOPHZ2 … sp=sharing

Here is my screen recording:

https://i.imgur.com/98kX24o.gif

6

Re: Why crosstalk from playback to analog mic input?

Well, all you can do then is use other mics that don't require such adapters, or an external headphone amp that removes the load on the output.

Regards
Matthias Carstens
RME