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-   -   iMac G3 350 MHz - distorted sound input/output with Xubuntu! (https://www.linuxquestions.org/questions/linux-hardware-18/imac-g3-350-mhz-distorted-sound-input-output-with-xubuntu-725353/)

Cyanaether22 05-12-2009 01:37 AM
iMac G3 350 MHz - distorted sound input/output with Xubuntu!
 
Hey, I installed Xubuntu on my old iMac G3 350 MHz Power PC slot-loading bondi blue model. The main purpose of this being to set this computer as a recording device.

But.. the sound input AND output are both distorted - not terribly, but not clean at all. this won't do for recording ;) and listening to music isn't as enjoyable.

Since it's both input and output - and in the headphone jack output too, I'm thinking it's a sound card issue, lack of config perhaps. I don't think this issue was occuring while running Mac OS 9 (but i intend to test this theory by booting into mac os 9 and trying out some sound) so maybe i can configure alsa to work better?

Any ideas? There is no indication as to what sound card lives inside the imac, apparently it's built-in to the motherboard and not coming out.

Cyanaether22 05-12-2009 07:17 PM
I checked out a few things and have more information:

Code:
teagankelk@kelkimac:~$ lspci
0000:00:0b.0 Host bridge: Apple Computer Inc. UniNorth AGP
0000:00:10.0 Display controller: ATI Technologies Inc Rage 128 RL/VR AGP
0001:10:0b.0 Host bridge: Apple Computer Inc. UniNorth PCI
0001:10:17.0 Class ff00: Apple Computer Inc. KeyLargo Mac I/O (rev 02)
0001:10:18.0 USB Controller: Apple Computer Inc. KeyLargo USB
0001:10:19.0 USB Controller: Apple Computer Inc. KeyLargo USB
0002:20:0b.0 Host bridge: Apple Computer Inc. UniNorth Internal PCI
0002:20:0f.0 Ethernet controller: Apple Computer Inc. UniNorth GMAC (Sun GEM)
Code:
teagankelk@kelkimac:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Screamer [PowerMac Screamer], device 0: PMac Screamer [PowerMac Screamer]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
Code:
teagankelk@kelkimac:~$ cat /proc/asound/cards
 0 [Screamer      ]: PMac Screamer - PowerMac Screamer
                      PowerMac Screamer Rev 0
The distortion seems to minimize when i turn everything's volume down and use an external source to amplify it... so that's why everything's turned down in the following config to 0. NOTE THAT FOR SOME REASON, 0 is not mute. this applies to the capture and playback channels. both of them are still getting fair volumes at 0, both distorted slightly.

possibly related to this bug report - https://bugs.launchpad.net/alsa-utils/+bug/16454

Code:
teagankelk@kelkimac:~$ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined cswitch cswitch-joined
  Playback channels: Front Left - Front Right
  Capture channels: Mono
  Limits: Playback 0 - 15
  Mono: Capture [off]
  Front Left: Playback 0 [0%] [on]
  Front Right: Playback 0 [0%] [on]
Simple mixer control 'Headphone Detection',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Line',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [on]
Simple mixer control 'CD',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [off]
Simple mixer control 'Mic',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [off]
Simple mixer control 'Mic Boost',0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 2
  Mono: 0 [0%]
Simple mixer control 'PC Speaker',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 15
  Mono:
  Front Left: Playback 0 [0%] [off]
  Front Right: Playback 0 [0%] [off]
Simple mixer control 'Capture',0
  Capabilities: cvolume
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 15
  Front Left: Capture 0 [0%]
  Front Right: Capture 0 [0%]
Simple mixer control 'Auto Mute',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Beep',0
  Capabilities: pvolume pvolume-joined
  Playback channels: Mono
  Limits: Playback 0 - 100
  Mono: Playback 20 [20%]
Code:
teagankelk@kelkimac:/proc/asound$ cat modules
 0 snd_powermac

teagankelk@kelkimac:/proc/asound$ cat modules
 0 snd_powermac

teagankelk@kelkimac:/proc/asound$ cat modules
 0 snd_powermac
I wonder if it's also reltaed to this bug topic - https://lists.ubuntu.com/archives/ub...er/049161.html .

PLEASE HELP. I'm considering switching back to mac os. the sound is the most important thing about this computer, it's meant for recording.

bucovaina78 09-18-2011 12:34 PM
I'm experiencing the same problem with Debian 6.0. Distorted sound as well.


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