Re: Annoying whitenoise sound coming from snd_hda enabled chipset

Finally at my work desktop ...

On Sat, Feb 21, 2009 at 12:49 PM, Ben Kaduk <minimarmot_at_gmail.com> wrote:
> On Sat, Feb 21, 2009 at 8:06 AM, Alexander Motin <mav_at_freebsd.org> wrote:
>> Garrett Cooper wrote:
>>>
>>>    I don't know how else to describe it, but when I turn up my
>>> speakers enough (50%+) and don't have any sound playing, I hear a
>>> whitenoise hiss coming out of them. When I change webpages (nvidia
>>> driver is GIANT locked) or do something else kernel intensive it stops
>>> for a brief second, but apart from that it's an annoying trill sound
>>> almost like a mosquito humming around me waiting to be swatted.
>>
>> I think it may be radio interference with disconnected microphone inputs.
>> Try to set all unneeded mixer volumes to 0, especially mic, monitor, speaker
>> and mix. Inputs often have too sensitive 20-30dB pre-amplifiers. Some codecs
>> have them on all inputs.
>
> It's hard to be sure, since I'm not sure that I could describe what I
> hear any better than Garret did, but I think I'm seeing the same sort
> of thing on my work desktop.  I'll try setting unneeded volumes to
> zero the next time I'm in, and see if that helps.
>
> dmesg and pciconf are available here:
> http://stuff.mit.edu/afs/sipb.mit.edu/user/kaduk/freebsd/periphrasis/

I'm still getting the noise, even with these mixer settings:
periphrasis# mixer
Mixer vol      is currently set to  25:25
Mixer pcm      is currently set to  25:25
Mixer speaker  is currently set to   0:0
Mixer mix      is currently set to   0:0
Mixer rec      is currently set to   0:0
Mixer monitor  is currently set to   0:0
Recording source:

(One of the upgrades neede me to set hw.snd.default_unit=1, but that's
unrelated.)

Now that I'm actually listening to the noise, I'm not sure that it's
really something
I would describe as white noise --- the frequency distribution is only
on a fairly narrow
band of relatively high frequency.
Setting the mixer entirely to zero does not eliminate the noise.
Things like switching between workspaces in KDE or scrolling up and
down in firefox
using the scroll wheel cause the noise to disappear during those actions.

I just now tested switching back to hw.snd.default_unit=0 and using
the headphone
jack on the back of the machine (soldered directly to the motherboard), and the
noise is still present, though slightly quieter than using the front
panel headphones
jack.

Any thoughts are greatly appreciated.

-Ben Kaduk