Alsa: Only right-side sound

girzel · 2012-07-18 03:07:22

I've got a fairly ancient desktop serving as a headless MPD-powered music server. I'm using straight alsa rather than pulse, since pulse doesn't seem suited to managing system-level sound. Speakers are plugged into the headphone jack in front. All was working well until a few days ago, when sound went out on the left. I'm sure it's not a speaker/jack issue: the jack in front is left/right combined, but there are split left/right jacks in back, and no matter how I plug things in, I only get the right channel. Running "speakertest -c 2" confirms that: only fuzz on the right.

I'm fairly certain I haven't changed anything, but I wanted to run through potential software problems before I start looking at the sound card. I have:

1. No ~/.asoundrc or /etc/asound.conf

2. This card

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: I82801DBICH4 [Intel 82801DB-ICH4], device 0: Intel ICH [Intel 82801DB-ICH4]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: I82801DBICH4 [Intel 82801DB-ICH4], device 4: Intel ICH - IEC958 [Intel 82801DB-ICH4 - IEC958]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

3. Drivers (nothing relevant is blacklisted):

$ lsmod | grep '^snd'
snd_cs4236             22144  0 
snd_mpu401              3568  0 
snd_wavefront          27954  0 
snd_intel8x0           22768  1 
snd_ac97_codec         89900  1 snd_intel8x0
snd_wss_lib            18147  2 snd_wavefront,snd_cs4236
snd_mpu401_uart         4943  3 snd_wavefront,snd_cs4236,snd_mpu401
snd_rawmidi            14630  2 snd_wavefront,snd_mpu401_uart
snd_pcm                61237  4 snd_ac97_codec,snd_intel8x0,snd_wss_lib,snd_cs4236
snd_opl3_lib            7218  2 snd_wavefront,snd_cs4236
snd_page_alloc          5837  3 snd_intel8x0,snd_wss_lib,snd_pcm
snd_hwdep               4746  2 snd_wavefront,snd_opl3_lib
snd_timer              14902  3 snd_wss_lib,snd_pcm,snd_opl3_lib
snd_seq_device          4316  2 snd_rawmidi,snd_opl3_lib
snd                    44426  15 snd_ac97_codec,snd_intel8x0,snd_hwdep,snd_timer,snd_wss_lib,snd_pcm,snd_rawmidi,snd_wavefront,snd_mpu401_uart,snd_seq_device,snd_cs4236,snd_opl3_lib,snd_mpu401

4. devices:

$ ls -l /dev/snd
total 0
drwxr-xr-x 2 root root       60 Jul 18 10:40 by-path
crw-rw---- 1 root audio 116, 10 Jul 18 10:40 controlC0
crw-rw---- 1 root audio 116,  3 Jul 18 10:40 controlC1
crw-rw---- 1 root audio 116,  2 Jul 18 10:40 midiC1D0
crw-rw---- 1 root audio 116,  9 Jul 18 10:40 pcmC0D0c
crw-rw---- 1 root audio 116,  8 Jul 18 11:03 pcmC0D0p
crw-rw---- 1 root audio 116,  7 Jul 18 10:40 pcmC0D1c
crw-rw---- 1 root audio 116,  6 Jul 18 10:40 pcmC0D2c
crw-rw---- 1 root audio 116,  5 Jul 18 10:40 pcmC0D3c
crw-rw---- 1 root audio 116,  4 Jul 18 10:40 pcmC0D4p
crw-rw---- 1 root audio 116,  1 Jul 18 10:40 seq
crw-rw---- 1 root audio 116, 33 Jul 18 10:40 timer

5. amixer reports that everything that has "Playback channels: Front Left - Front Right" also has both those channels set equally: both on, and volume the same. I'm assuming Master, Headphone and PCM are the relevant channels.

6. alsamixer is using the "default" soundcard, and everything that ought to be unmuted seems unmuted. I don't see any left/right specific controls, but if I go to either Master or PCM and use the QZ/EC keys to change left and right specifically, it confirms that only the right side is producing sound.

Is there anything else I can look at? Is it even possible that the sound card itself has gone wrong in such a way that only one channel plays?

Thanks!

Eric

DSpider · 2012-07-18 07:43:15

You mean:

$ speaker-test -c 2

Maybe the front panel has issues. Does the same thing happen if you plug the speakers in the back of the PC?

Do you have any other speakers to test it with? Maybe a friend's or a neighbour's. Also test the speakers on a different computer, to make sure that they're fully functional. Oh, and run "amixer" and see if you get something like:

$ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 65536
  Mono:
  Front Left: Playback 25520 [39%] [on]
  Front Right: Playback 25520 [39%] [on]
Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch cswitch-joined penum
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 65536
  Front Left: Capture 65536 [100%] [on]
  Front Right: Capture 65536 [100%] [on]

girzel · 2012-07-18 09:07:58

DSpider wrote:

Maybe the front panel has issues. Does the same thing happen if you plug the speakers in the back of the PC?
Do you have any other speakers to test it with? Maybe a friend's or a neighbour's. Also test the speakers on a different computer, to make sure that they're fully functional.

Yes, as I mentioned:

I'm sure it's not a speaker/jack issue: the jack in front is left/right combined, but there are split left/right jacks in back, and no matter how I plug things in, I only get the right channel.

I also used the same speakers on a different computer -- no problem.

DSpider wrote:

Oh, and run "amixer" and see if you get something like:

$ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 65536
  Mono:
  Front Left: Playback 25520 [39%] [on]
  Front Right: Playback 25520 [39%] [on]
Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch cswitch-joined penum
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 65536
  Front Left: Capture 65536 [100%] [on]
  Front Right: Capture 65536 [100%] [on]

Yup, again see my original post.

Thanks
Eric

DSpider · 2012-07-18 10:21:19

Do you dual boot with something? A LiveCD would also work (but not the Arch LiveCD; it's too minimal). See if you get sound there.

girzel · 2012-07-18 14:36:37

Nope, don't dual boot. I've got an Xubuntu install disc around here somewhere, I guess I could try with that.

girzel · 2012-07-20 09:56:06

Same problem on the install disc -- guess it's a hardware issue! Sorry for the noise.

Arch Linux

#1 2012-07-18 03:07:22

Alsa: Only right-side sound

#2 2012-07-18 07:43:15

Re: Alsa: Only right-side sound

#3 2012-07-18 09:07:58

Re: Alsa: Only right-side sound

#4 2012-07-18 10:21:19

Re: Alsa: Only right-side sound

#5 2012-07-18 14:36:37

Re: Alsa: Only right-side sound

#6 2012-07-20 09:56:06

Re: Alsa: Only right-side sound

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