Q is for Quadraphonic (Shallow Thoughts)

Q is for Quadraphonic

... which is what I have now on my Carbon X1 gen 7 laptop.

Early reviews of this particular laptop praised its supposedly excellent speakers (as laptops go), but that has never been apparent on Linux.

It is an improvement over the previous version -- the microphone works now, which it didn't in 19.10 -- though in the meantime I acquired a Samson GoPro based on Embedded.fm's recommendation (it works very well).

But although the internal mic works now, the sound from the built-in speakers is just terrible, even worse than it was before. The laptop has four speakers, but Ubuntu is using only two.

But the long, ongoing thread on the Lenovo forums on X1 Carbon 7th Generation on Ubuntu pointed me to the solution: as root, run:

/usr/bin/hda-verb /dev/snd/hwC0D0 0x17 SET_CONNECT_SEL 1

This has something to do with using the microphone channel to control the rear (bass) speakers; though in practice, what it does is enable the extra speakers and make them available as a "bass speakers" channel in alsamixer. The result is magical. It's especially fun to start playing music with only the front speakers, then run this command while the music is playing. What a difference! It's still not exactly audiophile quality, nowhere near a decent set of external speakers, but for a laptop it's not bad.

I believe this only works on Ubuntu 20.04. CX1 gen 7 users on earlier Ubuntus or other OSes may need to wade through the long Gist discussion: Lenovo Carbon X1 Gen 7 - Audio and microphone fix.