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Sound with VIA on-board

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Well, the MDK 9.2 offers 2 modules for my VIA 8253 onboard soundcard. With one I get duplex, but awful sound, with the other no duplex but perfect sound. What can it be? Could it be necessary to recompile the kernel?

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you mean 8235? I have it and use alsa's snd-via82xx w/ duplex and it's great. A kernel compile will just get you the same drivers.

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As root type alsamixer in a shell (with the snd-module) and see if it changes by chabnging the volume:


there is a better way: your snd-module has options for this purpose here is a siet with some explanation(the file is /etc/modules.conf):




the text what matters:


the chip with the revision 0x40, which is called VIA8233A, has no DXS

mode. other revisions, VIA8233, 8233C and 8235, do support it.

each DXS channel (from 0 to 3) has an indepedent stereo volume.

please make sure that these volumes, "VIA DXS Playback Volume", are

set to full (although they are initialized to full as default).


unfortuantely, some motherboards have the problems of DXS channels.

on some, DXS mode doesn't work at all, and on some, only 48kHz is

available (otherwise you'll hear click noises).

according to the people of VIA tech, this is because of the BIOS

(typically AWARD BIOS). so, one solution is to update the BIOS.

but it's not always a preferred solution.


in the recent driver version, a workaround is provided instead.

there is a module option "dxs_support", which defines how to handle

the DXS channels. if you have a problem with the first pcm device,

try dxs_support=2 or dxs_support=3.


when dxs_support=2 is given, the DXS mode is disabled and you'll have

only the multi-channel playback mode. this means, the chip is handled

as VIA8233A. of course, you can play only on stream. in this case,

dmix plugin would be a workaround.


when dxs_support=3 is given, only 48kHz is allowed for the DXS

channels. that means, the sample-rate conversion will be done in

alsa-lib or OSS-emulation for playing MP3. but it's cheaper than dmix

plugin. so, try this once, and if still doesn't work, try the

previous one.


how to add such an option? if you already have module options for

via82xx driver, you should see the line like following in



options snd-via82xx index=0


and just add dxs_support=2 (or 3) there.


options snd-via82xx index=0 dxs_support=2


then restart the driver(remove the drive with rmmod and put it back in with modprobe..after a modprobe it can be that all your soundlevels are 0, so raise them some befor eyou try it.)

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Michel, thanks for the info/links! I've been meaning to go to via arena but been lazy. Have you tried the viaudiocombo? Better than alsa? From the reading at via arena, it appears it may be a little better.

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I have a problem with my onboard VIA sound too, it can only use 1 channel at a time, so it can not play music and sounds toghther and that's pretty sucky when you play games with WineX from whom you know they have good background music :(


I have checked the ALSA Mixer and my manual, according to those I have version VT82C686A/B,VIA's site learns that this card is only supported with Mandrake 8.2. Does that mean there is no solution to my problem ? I hope not ...

Edited by iNFERiON

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