[alsa-devel] HDA Conexant: is mic boost possible?

Tobin Davis tdavis at dsl-only.net
Wed Sep 5 03:15:05 CEST 2007

I believe mic boost is on by default.  What model are you running this
as?  Laptop or Fujitsu?


On Tue, 2007-09-04 at 11:14 -0300, Pablo N. Hess wrote:

> I have to make the sound chip of a Itautec W7635 (= FIC VA250D) work on 
> a Gentoo(-based) distro (I'm now trying Sabayon).
> It is a HDA-intel (Conexant codec).
> Using my earphones as a stereo mic, recording with 'arecord -f cd' has 
> always worked perfectly fine, from alsa-driver-1.0.14 on.
> However, when using a regular mono mic (like the ones that come in 
> common headsets), recording simply does *not* work.
> Here's the quick info:
> alsa-driver-1.0.14:
>    playback: ok
>    recording:
>      stereo mic: ok
>      mono mic: no input at all (very high volume already tried)
> alsa-driver-1.0.15rc1:
>    playback: ok (even better than with alsa-driver-1.0.14)
>    recording:
>      stereo mic: ok (seems better thatn with alsa-driver-1.0.14)
>      mono mic: *very* very low volume, bad quality, lots of low-volume 
> noise, too.
> Now the paragraphed info:
> Playback is perfectly ok since alsa-driver-1.0.14, just like recording 
> with an earphone as a stereo mic.
> With alsa-driver-1.0.14, definitely no mono-mic input works, no matter 
> the settings at alsamixer.
> With alsa-driver-1.0.15rc1, mono-mic input works very very bad 
> (extremely low volume, terrible quality, lots of clicks and noise).
> I guess that the mono mic needs a mic boost in alsa-driver-1.0.15rc1. 
> However, with a 'grep -i "mic boost" .../pci/hda/*.c' 
> (alsa-driver-1.0.15rc1 source code), it seems that only patch-realtek.c 
> and patch-analog.c support this feature.
> Is it even possible to add a mic boost feature to this codec?
> The output of alsa-info.sh with alsa-driver-1.0.15rc1 is at:
> http://pastebin.ca/681023
> Thanks a lot for any info, and congratulations to all of you for your 
> terrific work with ALSA.
> Pablo Hess
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Tobin Davis  

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		-- Professor Freund, Communication, Ramapo State College

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