sound issue on iMac 5,1 - headphone jack works, speakers dont

[jamesey]

I got a new iMac this weekend. I have no intention of running MacOS (for reasons that belong in a whole other thread.) I got it, booted up to Mac OS, installed rEFIt, and burned a copy of Ubuntu 8.10.

The install went smooth. Everything works, except this nagging but vital sound issue.

I get sound out of my headphone jack. I don't get sound out of my speakers. I'm not too familiar with PulseAudio/ALSA, so any help to fix this would be greatly appreciated. I'll write a guide for installing Ubuntu on a MacTel to publish across a few forums and wiki's once I figure out this last issue.

[D-cat]

Certain chipsets are known to cause this for a few reasons (misread softswitch, bad pinout specs, etc).

If in a terminal you type alsamixer -c0 , in the upper left corner could you please tell us what it lists for card and chipset?

Also the output of lspci | grep -i audio

Thank you.

[jamesey]

lspci | grep -i audio
00:08.0 Audio device: nVidia Corporation MCP79 High Definition Audio (rev b1)

[D-cat]

Believe it or not, there is an open bug report on this issue (found it using the alsamixer chip output). It's not solved yet, but it is confirmed that the headphone switch setting is backwards. There is a less than ideal workaround, which exploits the reversed switch (plug in headphones, make mixer adjustment, get sound out your speakers):

Snowball2050 wrote on 2008-06-01: (permalink)

I've come up with a non-ideal fix for my problem. I found out that what is really going on is that ubuntu is mixing up my headphone jack and speaker outputs.

With "options snd-hda-intel model=auto" set in /etc/modprobe.d/alsa-base:
When I plug my headphones into the headphone jack, it believes it to be the speakers and is already outputting sound. Laptop speakers do not function even when switches in the volume control are toggled. <-----Thus headphone only sound

With "options snd-hda-intel model=arima" set in /etc/modprobe.d/alsa-base:
When I plug headphones into the headphone jack nothing happens. When I toggle Headphone switch to 'checked' in volume control, playback can be heard from laptop speakers! If I uncheck it, I can still get headphone sound from the "Front" output jack as this would always be on anyhow.
When I toggle the headphone switch, I can see in alsamixergui the mute toggles going on and off for the headphone channel. It is not possible to toggle the mute for the PCM channel. Volume is controlled by using the PCM, Front, or Master sliders; Headphone sliders are nonexistant.

[jamesey]

This is my alsa-base file. I'm not sure what to add or change.

# autoloader aliases
install sound-slot-0 /sbin/modprobe snd-card-0
install sound-slot-1 /sbin/modprobe snd-card-1
install sound-slot-2 /sbin/modprobe snd-card-2
install sound-slot-3 /sbin/modprobe snd-card-3
install sound-slot-4 /sbin/modprobe snd-card-4
install sound-slot-5 /sbin/modprobe snd-card-5
install sound-slot-6 /sbin/modprobe snd-card-6
install sound-slot-7 /sbin/modprobe snd-card-7

# Cause optional modules to be loaded above generic modules
install snd /sbin/modprobe --ignore-install snd && { /sbin/modprobe --quiet snd-ioctl32 ; : ; }
install snd /sbin/modprobe --ignore-install snd && { /sbin/modprobe -Qb snd-seq ; }
install snd-pcm /sbin/modprobe --ignore-install snd-pcm && { /sbin/modprobe --quiet snd-pcm-oss ; : ; }
install snd-mixer /sbin/modprobe --ignore-install snd-mixer && { /sbin/modprobe --quiet snd-mixer-oss ; : ; }
install snd-seq /sbin/modprobe --ignore-install snd-seq && { /sbin/modprobe --quiet snd-seq-midi ; /sbin/modprobe --quiet snd-seq-oss ; : ; }
install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi && { /sbin/modprobe --quiet snd-seq-midi ; : ; }
# Cause optional modules to be loaded above sound card driver modules
install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe -Qb snd-emu10k1-synth ; }
install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe -Qb snd-seq ; }

# Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway)
install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe -Qb saa7134-alsa ; : ; }

# Load snd-seq for devices that don't have hardware midi;
#   Ubuntu #26283, #43682, #56005; works around Ubuntu #34831 for
#   non-Creative Labs PCI hardware
install snd /sbin/modprobe --ignore-install snd && { /sbin/modprobe -Qb snd-seq ; }
# Prevent abnormal drivers from grabbing index 0
options bt87x index=-2
options cx88_alsa index=-2
options saa7134-alsa index=-2
options snd-atiixp-modem index=-2
options snd-intel8x0m index=-2
options snd-via82xx-modem index=-2
options snd-usb-audio index=-2
options snd-usb-usx2y index=-2
options snd-usb-caiaq index=-2
# Ubuntu #62691, enable MPU for snd-cmipci
options snd-cmipci mpu_port=0x330 fm_port=0x388
# Keep snd-pcsp from beeing loaded as first soundcard
options snd-pcsp index=-2
model=mbp3
options model=mbp3

[D-cat]

Add a new line to the bottom of the file, containing the content:

options snd-hda-intel model=arima

Make sure it ends with a new line. Save and restart.

[jamesey]

Add a new line to the bottom of the file, containing the content:

options snd-hda-intel model=arima

Make sure it ends with a new line. Save and restart.

if I try that option, I get no sound from headphones or speakers

if I change it to
options snd-hda-intel model=arima
I get headphone noise

I guess that is something

[D-cat]

When I toggle Headphone switch to 'checked' in volume control

Did you check the headphone option in the mixer?