Popping with snd-usb-audio

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NathanZachary · Post by **NathanZachary** » Wed Oct 15, 2014 9:28 pm

Hello all,

I've been fighting with this problem for quite a while now, and I'm out of ideas. I have a music server running Gentoo with MPD, and it is connected to my preamp/processor via asynchronous USB. I get a lot of pops/clicks when the following things happen:

* The music server is booting up or powering down
* Adjusting the volume of playback on my preamp/processor
* Starting or stopping playback of a song via MPDroid / MPD
* Unplugging or plugging in the USB cable between the music server and preamp/processor

Other than the popping sound during these functions, everything is working smoothly. I thought that it might be related to powersave options, but I don't know that those can be disabled for snd-usb-audio like it can be with other ALSA drivers.

Any suggestions on how to continue troubleshooting?

Thank you preemptively!

Cheers,
Nathan Zachary

NathanZachary · Post by **NathanZachary** » Fri Oct 17, 2014 12:02 am

I'm thinking that it may possibly be that the connection to the sound hardware (via asynchronous USB) is being activated and then put to sleep. When there is music playing, and I adjust the volume of playback on the preamp/processor, I don't get any popping or clicking. I tested this by creating a FLAC file that was essentially silence. It kept the hardware "activated" since it was technically playing back music, and that stopped the popping. Is there a way to instruct MPD or ALSA to essentially not allow the hardware to go to sleep?

My terminology or logic may be inaccurate or flawed (respectively), but it seems to make sense.

Any thoughts?

NathanZachary · Post by **NathanZachary** » Wed Oct 22, 2014 4:09 pm

Any suggestions at all? After playing back the "silent" FLAC and not hearing the popping on volume adjustment, I'm really thinking that the sound hardware is going to sleep in between each action. I think that you can get the hardware to never sleep by using PulseAudio and removing the "module-suspend-on-idle" line from the configuration. I would rather not use PulseAudio unless absolutely necessary, so does anyone have a suggestion for just MPD and/or ALSA?

Thanks.

Cheers,
Nathan Zachary