Fast Track Pro sample rate problem

Brian David beejunk at
Mon Jun 21 14:31:36 BST 2010

On Sun, Jun 20, 2010 at 7:05 PM, Rick Bragg <lists at> wrote:

> Hi,
> I am looking at the documentation for my M-Audio Fasttrack Pro and it
> can do up to 96k 24bit recording, however, I am trying to fire it up
> with qjackctl and it I can't get it to do anything other than 16 bit
> little endian 44100 sample rate.  I get an error in the messages that
> says the playback and capture sample rates do not match.
> I am using the latest Ubuntu 10.04LTS with
> Following are my "messages"
> Does anybody know how I can get the most out of this device?
> Thanks
> Rick
Not sure why your playback rates and capture rates are different, and I'm
also not sure why it settles at 16bit.  I've never used a USB interface with
JACK before.  However,  I can maybe give you some info on other issues that
might help.

First, even though your interface (and many others) can do 96khz, you
probably should not use that high a rate.  The theoretical improvements in
quality do not outweigh the negatives.  It's a long topic, so I won't get
into it here, except to say that there's plenty of material to read on the
Internet about it (such as this informative thread at the Ardour forums:  This is probably one of the reasons  you are
getting so many X-runs.  I would suggest just using 44.1 khz.

Other than that, it would be nice to know more details about your set-up.
In particular:

-What kernel are you using?  If you're using an RT kernel, make sure that a)
you have JACK set to use realtime, and b) you have some sort of script
installed that sets realtime thread priorities (such as the rtirq-init
script in the repositories).  If you're using Ubuntu Studio, you should
already have this script installed.

-If you've got Network Manager installed (which you probably do), make sure
to disable networking prior to starting JACK.  You can do this via the
context menu by right-clicking on the notification applet.  Network Manager
has been known to cause issues with the sound server.

Those are the easy things to try out.  Hopefully they improve your

-Brian David
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