[LAU] Jack issue

Patrick Shirkey pshirkey at boosthardware.com
Mon Aug 3 20:22:08 EDT 2009

> my config:
> Dell Studio
> Ubuntu 9.04
> rt kernel
> jackd version 0.116.1 tmpdir /dev/shm protocol 24
> Ardour 2.7.1 (built from revision 4296)
> USB iMic audio interface
> KOrg nanoKontrol
> cpufreq-set - both cpu's are set to 2.0GHz and userspace
> I'm trying to get Jack and Ardour set up/optimized for my fall tour
> I'm using the rt kernel as stated above
> my Jack settings are 44.1kHz: frames 512: periods 5
> latency is not a huge issue for me since I'm only playing back audio for
> a live mix situation
> and xruns in Jack seem to be tamed to 0 during playback
> my Ardour session is 30 minutes in length, has 8 tracks of audio, and
> the fader levels are assigned to the nanoKontrol
> everything works fine for the session except at some random point after
> playing for a while I get a single short burst of AM sideband noise,
> like I'm multiplying the audio on the mix buss by another audio signal
> it doesn't happen (so far) more than once per session and it doesn't
> seem to be correlated to anything like mix buss levels or clipping on a
> single channel etc
> is there a setting in Jack that I'm overlooking or has anyone
> experienced a similar intermittent burst of noise in playback with
> similar Jack settings? or if this topic has already been discussed can
> someone point me to a link in the archives? I wasn't able to find
> anything on a cursory search

This could be one of several issues.

1: A driver bug.
2: A bug in the version of Ardour that you are using.
3. It may be related to having a daemon process running that spikes your 

To check for the latter you would need to run a monitoring app like 
gkrellm or top and monitor it while you have the session playing to 
check if any spikes occur. It's probably also possible to print a status 
report to stdout so you can check back.

If it's a driver, jack or Ardour bug I haven't heard of it. IMO if it's 
not an external process causing the spike it's a 50/50 chance it's 
more the driver for the imic than a bug in the version of Ardour.

If you can rule out the spike option that would be helpful.


Patrick Shirkey
Boost Hardware Ltd

> ================
> -- also, I  started Ardour from command line when Jack wasn't running
> and I got three panels in the open dialog box -- one of them being a
> Audio Setup panel
> -- is there a way to see this panel after starting Ardour with Jack
> already running?
> _______________________________________________
> Linux-audio-user mailing list
> Linux-audio-user at lists.linuxaudio.org
> http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user

More information about the Linux-audio-user mailing list