[LAU] UA25 noise problem w. nVidia chipset

[david]

Giso Grimm wrote:
> 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.

Also depends on the presence or absence of an externally-powered 
external USB hub. I have an external USB2 hub (having three USB ports on 
laptop and 8 devices to plug into them). Running my USB soundcard 
through the external hub provided large bundles of noise. Hooking it 
directly to a USB port on the laptop abolished the noise. Probably bad 
grounding in the external hub or its power supply.

-- 
David
gnome at hawaii.rr.com
authenticity, honesty, community