Shush to the snap, crackle, and pop

Oct 4, 2018, updated Dec 24, 2018 hugo

Update: See foot of page if you’re on Ubuntu 18.04

From time to time I pretend to be a swing DJ of sorts. Mostly this has been for The Balboa Café which I used to run before heading to Sweden, but sometimes also for dance classes or other events.

My Dell XPS 13 (9350 edition) running Ubuntu (currently 16.04.05 LTS) at some point acquired an irritating audio problem:

• When sound is playing it’s fine
• When sound finishes it makes a pop
• As sound starts it makes a pop
• When no sound is playing there is low level hiss/crackle noise
• All of this is only on the headphone jack - built in speakers are fine

That smells like a power management issue to me - a pop when the audio hardware is started or stopped, and noise when the audio hardware isn’t running to hold the signal low from interference. However. I just got around to looking up the appropriate Ubuntu incantation and, yep, looks like it fixes it:

The following command turns off the power management for the intel audio hardware in this XPS:

All of the unwanted noises go away. If you’re not using the headphone jack or are willing to put up with the noise for the battery savings and want to turn power management back on:

Just putting this out there for anyone with the same issue. Enjoy!

Update: Having finally bitten the bullet and upgraded to Ubuntu 18.04 I find that the problem described above is now fixed. However, there’s now a constant hiss audible on headphones which wasn’t there before. Not being a fan of the retro C90 cassette audio texture I had a poke around and found the following bug report with a few suggestions:

https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1654448

For me the following command works nicely to remove the hiss when I’m listening to music (or playing it for others):

I’ll update this post again if I have further issues/solutions, but for now I’m pretty happy again.