1 (edited by Axel Himself 2013-08-26 13:49:59)

Topic: [UCX via Firewire] Sometimes crackles no matter which buffer size

Hi there,

since my Fireface 400 got stolen some weeks ago (yes, people like it), I bought myself the UCX. I am using it on a Macbook Pro Retina 15" (Mid 2012) with Ableton Live 9.0.5 running with a buffer size of 93 samples. The UCX is connected through Firewire via Apple's Thunderbolt to FireWire Adapter, in the same way I was using the Fireface 400 before. So the only thing that has changed on my system is the interface (and the driver which I updated to the latest version).

Now here comes my problem. On starting up Live and loading my session everything is working fine. However, after some time or certain actions (e.g. audio recording, re-opening the session, closing and re-opening Live) I can hear a quite constant crackling sound when beeing in play, just as if the buffer size is too low.
In that case it does NOT help to increase the buffer size. The workaround is to switch Live's audio driver from the UCX to "Built-In" and then back to the UCX.

So far I've found two reports here on the forum that sound at least similar:

http://www.rme-audio.de/forum/viewtopic.php?id=15109
http://www.rme-audio.de/forum/viewtopic.php?id=18161

I did not check if I get this problem when running the UCX via USB since all my USB ports are taken, but in case that information would be helpful to the QA, I'm willing to give it a try.

I've never seen this problem with my older Fireface 400 on that very same system.

BTW: The problem occurs no matter if I'm running the UCX bus-powered or with the power adapter.

If you have any hints or news regarding this issue, I'd be very happy.
Thank you very much in advance!

Axel

--
Macbook Pro Retina 15", Mid 2012
OS X 10.8.4
Ableton Live 9.0.5
Mac OS X Intel driver for Fireface 400, 800, UCX, UFX, version 3.16 (plus latest firmware)
Apple Thunderbolt to FireWire Adapter

2

Re: [UCX via Firewire] Sometimes crackles no matter which buffer size

The UCX can not work with FW buspower via Thunderbolt. Have you made sure that when using the power supply that the switch on the back is in the correct position, so that power indeed comes from the ps, not FW?

Regards
Matthias Carstens
RME

Re: [UCX via Firewire] Sometimes crackles no matter which buffer size

Now, that is very interesting. I also assumed the UCX does not work bus-powered but for the first two weeks I was using it without the power adapter. No USB connection either. Only connected to the Thunderbolt port via Apple's Thunderbolt to FireWire Adapter. Except for the mentioned crackling issue, this was actually working just fine. Do you by "The UCX can not work with FW buspower via Thunderbolt" mean that it does not work at all or that it does work in general, but a stable connection cannot be guaranteed? I am asking because it's definitely working in my setup (I can send a video if you like)...

Every now and then this crackling problem appeared, so I thought it might help to switch from bus-powered to the power adapter, but this did not change anything in the behavior.

I'm pretty sure the power switch is now set to ON (not bus-powered) because to power on the fireface I have to switch on my socket board first. However, since I am not a 100% sure, I will explicitly check the next time the crackles appear. Thanks so far!

4

Re: [UCX via Firewire] Sometimes crackles no matter which buffer size

The UCX needs 12 Watts. TB delivers 7. It does not work, or not stable.

Regards
Matthias Carstens
RME

Re: [UCX via Firewire] Sometimes crackles no matter which buffer size

Three days of intensive use later, I can say that the problem has disapeared (when using the power adapter). So I might indeed have switched to bus-power unintentionally that very day.
Thanks for your help!
Regards, Axel