Eliminating crackling/distorted noise on Intel Mac computers running Ubuntu/Linux
on Saturday 17th May, 2008 Gabe speculated thusly…I have a first generation macbook coreduo.
The latest version of Ubuntu (Hardy Heron 8.04 LTS) works very well on it with minimal configuration. However, several issues remain. One of which is the poor sound quality. Initially, installing linux-backports-modules did the trick, however after several reboots it became clear that it didn’t always work. I came across this post, which I followed and the results were outstanding. I have completely copied it here, only to make sure there is another copy of this important document. Full credit for this one goes to the original author. Anyway, here’s what you need to do:
Edit the file /etc/modprobe.d/options
$ sudo vim /etc/modprobe.d/options
And add the following to the end of the file:
options snd-hda-intel model=[MODEL_BELOW] position_fix=2 probe_mask=1
Run the following command:
$ sudo update-initramfs -u
Then reboot.
You must select the Intel HDA model that corresponds to your computer:
These are the codes you can use in the above instructions:
intel-mac-v1 : Intel Mac Type 1
intel-mac-v2 : Intel Mac Type 2
intel-mac-v3 : Intel Mac Type 3
intel-mac-v4 : Intel Mac Type 4
intel-mac-v5 : Intel Mac Type 5
macmini : Intel Mac Mini (equivalent with type 3)
macbook : Intel Mac Book (eq. type 5)
macbook-pro-v1 : Intel Mac Book Pro 1st generation (eq. type 3)
macbook-pro : Intel Mac Book Pro 2nd generation (eq. type 3)
imac-intel : Intel iMac (eq. type 2)
imac-intel-20 : Intel iMac (newer version) (eq. type 3)
For example, I have a Macbook 1st generation, and the only setting that worked was
model=intel-mac-v1. All others just gave me no sound at all, including the apparently
obvious macbook and the documented-as-equivalent macmini ones.
If nothing works, you can revert this by deleting the line and performing the rest of the steps.
For BEST sound, if the above works, open a terminal and type:
$ alsamixer
And set the front and surround sliders to their maximum.
It might be necessary to unmute them with the ‘M’ key.
Press ESC twice to leave the program.