Re: Annoying whitenoise sound coming from snd_hda enabled chipset

On Tue, Feb 24, 2009 at 1:31 PM, Alexander Motin <mav_at_freebsd.org> wrote:
> Ben Kaduk wrote:
>>
>> 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:
>
> You have set vol and pcm to 25. They are measured not in percents now, there
> are a logarithmic scales inside codec, so, depending on model, 25 may mean
> something like -30dB, when you will be able to hear codec's native noise
> margin, which can quite high cheap codecs and cheap boards.
>
> Set your mixer to 80-100 and reduce volume on you speakers/amplifier.
>

Sadly, I am using headphones, with no additional amplification.

I think I was using the same or similar mixer settings in the old world order,
with the same loudness at my ear.  I would be surprised if the
change to logarithmic scale is solely responsible for this noise, but it
is plausible ...

-Ben Kaduk