I have a HP-DV6165tx.
In 11.10 to enable the sub woofers I had added this line to the
/etc/modprobe.d/alsa-base.conf file
options snd-hda-intel model=ref
After upgrading to 12.04 I had no sound.
So I changed it to
options snd-hda-intel model=hp
I ended with hp after a lot of trial and errors looking at the
/usr/share/doc/alsa-base/driver/HD-Audio-Models.txt.gz file
Now my speakers work but the 2 sub woofers are still not working. Any workaround to this?