[LAU] Behringer UCA202

[Ralf Mardorf]

arOn Wed, 23 Jan 2013 01:56:51 +0100, Len Ovens <len at ovenwerks.net> wrote:

>
> On Tue, January 22, 2013 1:26 pm, Bob van der Poel wrote:
>> Anyone with experience using the UCA202? I tried it the other day
>> using audacity and found that it played and recorded just fine if it
>> was only doing one or the other. But, if I had existing tracks in
>> audacity and played those (only 1 stereo) and recorded a 2nd track ...
>> the recorded track sounded like it was filtered though a motorboat
>> engine (sputter, sputter ...).
>>
>> I did the recording again directing the output to an existing device
>> and all worked fine. So the setup seems to be useable. I am thinking
>> that audacity (alsa?) can't read+write to the device?
>>
>> I'm running Ubuntu 12.04. Didn't have jack running.
>
> I have found with USB audio, I have to find a USB plug that has it's own
> IRQ. For example I have:
>
>  16:   12488044          0   IO-APIC-fasteoi   ehci_hcd:usb1,
> uhci_hcd:usb2, i915, ath9k
>  17:          0          0   IO-APIC-fasteoi   uhci_hcd:usb3
>
> That USB2 is the left side plug on my machine, the usb3 is the right... I
> only use the one on the right. I also have found I have to unload the
> wireless kernel module as it's once a minute scan gives xruns... once
> every five seconds if wireless is disabled.

As already mentioned in my first reply, it's possible to unbind devices  
that share the IRQ.
Another thing to do, that might help a little bit, is to make the USB port  
used by the sound device head of the USB devices by rtirq. Take care that  
the kernel and the rtirq script fit together. I'm using Ubuntu since  
years, most of the times the rtirq script from the repositories doesn't  
fit to the kernels of the repositories.

Instead of using an Ubuntu kernel, building a kernel-rt also might help a  
little bit.

Some people stop all unneeded services. This never improved anything on my  
machine, but it doesn't harm to stop unneeded services.

You could test jackd and set periodes/buffer (n) to 3.