Re: [tlug] No sound with USB device driving me crazy

[Scott Robbins <scottro@example.com>]

On Tue, Apr 17, 2007 at 02:42:36PM +0900, Dave M G wrote:
> Tapio,
> 
> 
> 
> $ alsamixer
> alsamixer: function snd_ctl_open failed for default: No such device

I can only give hints, not running Ubunutu.  In ArchLinux, my sound
module should theoretically be loaded on boot--as the saying goes,
theoretically often means, "Not really."

I sometimes have to reprobe the sound module--that's done with 

modprobe <module_name>.

Usually, if it's loaded successfully, there will be a /dev/dsp, and if
it doesn't get loaded, there won't be.  

Is this a recent problem?  If so, then Ubunutu wa Ubuntu-rashiku, and
once again, blithely threw in an update that broke things for many
people.  If so, check their bugs.ubuntu.com (I think--I'm typing that
from memory) and their forums for your model of sound card.  Hopefully,
if that is the case, it won't take them two releases to fix it, as, once
again hopefully, your card is newer than old Matrox video cards.  

Hope this helps, but it's a stab in the dark, since my sound problems
were on a different distribution, which unlike Ubuntu, isn't necessarily
aimed at the desktop user.  


> 
> Of course I looked this up on Google. A lot of sites say that when this error 
> occurs, it indicates that the card is not yet supported. However, I don't think 
> this is the issue in my case because my card is supported under ALSA's 
> snd_usb_audio drivers.
> 

Yes, but see above.  Perhaps Ubuntu accidentally lost support for this
particular card.  Also--even if a card is supported, it didn't
necessarily get loaded at boot--sometimes, this has to be specified
somewhere.  (Again, Ubuntu would do this differently, it might be in
modprobe conf or it might even be something in /etc/alsa something.)

This isn't that much help, but if the problem is that the module isn't
being loaded, and you can determine that, I'm sure someone can tell you
which files to check and modify on Ubuntu.  Note that doing lsmod and
finding the module is listed doesn't always indicate that it is actually
loaded and working, at least on Arch. 

The test would be (on Arch--again, this might be different for you, I'm
no sound expert, but should work.)

Firstly, check if there is a /dev/dsp and check its permissions. 
They should either be 666 (crw-rw-rw) or at least have your group as
rw, for example something like  crw-rw---   root  dave, or whatever your
group (as opposed to user name, is--this can be checked by simply
typing, while logged in, 

groups

That lists user dave's groups.

If it's not there, or even if it is, then try the modprobe <modulename>
where <modulename> is the module for your card, for example
modprobe snd_ich.

Then, try amixer or alsamixer again.  If you no longer get that
particular error, it means that we've found at least part of the
problem, and you have to figure out how to get the module loaded on
boot.


> I just don't get this. Somehow Ubuntu detects my exact Audio device, but then 
> can't or won't use it. How can that be?
> 
Ubunutu can be whimsical.... (X files music in background)


-- 

Scott Robbins

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