1 Topic by marcd (edited by marcd 2023-03-03 01:44:38)

  • marcd
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Topic: Audio out to UCX II sometimes drops during Mac Time Machine backup

Wondering if this is a driver issue or more of a fundamental Mac problem with my particular setup. Here is what I have:

Mac M1 Max, Ventura 13.2 --- TB4 cable ---> OWC Thunderbolt Dock
OWC Doc:
--- USB port ---> Samsung T5 ext HDD 1 (Time Machine backup)
--- USB port ---> Samsung T5 ext HDD 2 (just a normal extra storage)
--- TB3 port ---> LG 5k Display
--- TB3 port (USB C cable) ---> RME Fireface UCX II ---> Monitors

When I send Mac audio to the UCX and out to monitors, and a Time Machine backup starts, then sometimes the audio gets real choppy for a few minutes until the backup is complete. It doesn't happen all the time. If I'm at my desk all day, with automatic backups every 1hr, then it might happen 1 or 2 times per day. I.e. out of maybe 8 - 10 backups, only 1 or 2 get this corruption.

I know all this data is going through the OWC dock, but it should have plenty of bandwidth. For example, I'm sending 5k video out to the external display which is much higher bandwidth than stereo audio data, and there's no video lag or corruption during the Time Machine backup. So it seems somehow that either Mac or driver is down-prioritizing the audio feed versus the backup data, but that's just my impression I can't prove anything since I cannot reliably reproduce the issue.

I can live with it, but curious if anyone at RME has any ideas.

Thanks!

2 Reply by MC

  • MC
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Re: Audio out to UCX II sometimes drops during Mac Time Machine backup

You can't connect the  UCX II directly to the M1 Max?

Regards
Matthias Carstens
RME

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  • mkok
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Re: Audio out to UCX II sometimes drops during Mac Time Machine backup

I used to work on Cisco routers and switches and many times there were complaints that transferring large files caused problems with voice over ip. If there is no mechanism to reserve bandwidth for audio then even though you have the bandwidth it can be taken up and stop real-time audio.

If you have no way of prioritising real time applications then I would disable the backups while you are playing audio. Best bet is to be connected directly on a port that has its own controller. If you can’t do this then manage as above.

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Re: Audio out to UCX II sometimes drops during Mac Time Machine backup

If I had to guess (and I am), the TB Video is likely using a different sub-protocol inside Thunderbolt (DP over TB?) than the USB traffic you are sharing across drives and the RME.  As stated - use a direct port on your machine, and don't make the RME compete with drives and such on a common USB bus...

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