7 Apr
2011
7 Apr
'11
9:45 a.m.
Hi,
On 04/07/2011 12:34 AM, Dave Phillips wrote:
I've been working with Ardour3 on my laptop, a
machine with an AMD
Turion X2 CPU and an nVidia 8200M integrated video chipset. Recently I
started monitoring my test recordings through the headphone output of my
UA25 and I notice that when I move the mouse it creates scratchy sounds,
though QJackCtl reports no xruns and my recordings are unaffected. I
verified the problem with Ardour2 and Mixbus. It doesn't occur when I
use the integrate audio chipset (snd-hda-intel, wahoo).
we observed exactly the same problem (only on the output of a custom
made USB sound card). The noise was spikes of varying amplitude at a
fixed rate (125ms if I remember well). Replacing the USB cable by a
shorter one significantly reduced the problem, and it also depended on
the USB ports used for mouse and sound card. On some mainboards/laptops
the noise was less then on others.
See
http://vegri.net/output_zero.png and
http://vegri.net/output_inactive.png
for output spectrum of the sound card (custom made, not UA25) when
playing zeros and when not in use.
- Giso
Running 'cat /proc/interrupts' reports that usb1/usb3 share interrupt 17
and usb2/usb4 share interrupt 16. I've tried switching ports around but
that didn't get rid of the noise. Any further suggestions ?
Best,
dp
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