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JACK audio severe clipping distortion on ubuntu 5.11* with Ubuntu Studio & REALTEK ALC298 Built-in Audio

ar flag
Reu

I recently installed Kubuntu 20.04 on a new Razer Blade 15 (mid-2021) with built-in audio card Realtek ALC298. Everything has been working pretty well audio-wise, with PulseAudio working perfectly fine.

I recently installed SuperCollider and Reaper, two pieces of audio software that require JACK to run. I've installed JACK via the Ubuntu Studio packages. Now, however, whenever I boot the JACK server my audio becomes severely distorted, a bit like clipping distortion.

This seems to be the case with any audio coming from SuperCollider and Reaper. But also other applications, such as various software synthesizers. Even the volume control system sound starts to distort horribly above a certain level.

Does anyone have any idea what might be the issue? I've tried both generic and low-latency kernels.. (5.11.0)

thanks!

EDIT: This issue does not occur when using an external (USB) soundcard, in my case a Behringer UMC204HD. It seems to only be an issue with the ALC298 built-in audio.

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vu flag

for me adding the -S option to my .jackdrc magically resolved the distortion. I did not need to uninstall pulseaudio.

Reu avatar
ar flag
Reu
thanks @yota morimoto! adding the `jackd -S` option resolved the audio problem, although it only works when launching jack directly from the command line. Do you perhaps know if it's possible to configure jackd command line arguments in Ubuntu Studio Control?
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cn flag

I ran into the same issue with Ubuntu 20.04 and the older ALC255. The problem is somewhere between pulseaudio and jack, they don't act well together when they use the same soundcard. But it is possible! I've jack and pulseaudio now working like a charm for 1 1/2 years. You can either kill pulseaudio while your're using jack, which might not be desirable in your setting. Or you can route pulseaudio to jack with pulseaudio-module-jack and pavucontrol + pasystray.

sudo apt install pulseaudio-module-jack pavucontrol pasystray

pasystray is a nice little app for the system tray, that gives you control which soundserver to use as a "standard sink" or individually for seperate programms. It also gives you easy access to pavucontrol which gives you a little more control over pulseaudio.

I also suggest you read these two pages carefully, the second link explains how to setup pulseaudio-module-jack:

PulseAudio and Jack

How to setup pulseaudio-module-jack

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