ALSA or JACK ? release 4.2


I have a gnome ubuntu pc and another on ubuntu studio. The two are in release ARDOUR 4.2. JACK runs on 2.
On the GNOME ubuntu, ARDOUR starts with ALSA not with JACK
On STUDIO ubuntu, ARDOUR starts with Jack but not with ALSA

I would like the GNOME Ubuntu starts JACK

And if possible explain the run with ALSA and JACK ?

Best regards

I’m not sure if I have understood completely… have you already installed JACK also on the GNOME system?
If you’ve done it: You might open QJackCtl and start JACK. Afterwards you can start Ardour 4.2 and choose JACK instead of ALSA.

I’m sorry that I could explain the stuff about ALSA and JACK rather in German than in English… but to me JACK seems to be a kind of professional enhancement and supplement of ALSA.

If you understand French - there is a nice site about Linux and Audio including stuff about JACK and ALSA:

Hope this helps at least a bit :-)…

Thank you for your answer

I misspoke. On the computer with Unbuntu gnome: it start well with ALSA audio system setup in the audio / midi. I start jack with QJACKCTL ==> ok. Jack is running.
I change alsa by jack in the setup, he said: The session "/ does not load properly.
Before 4.2, ARDOUR was running with JACK on this computer.

On the computer with ubuntu studio it’s the opposite. It start well with Jack, but can not start with ALSA.

And this problem appear with ARDOUR 4.2. (i think)

Any idea ?


Sorry, I was not in real time (kernel). Now it’s ok.

@audio - rtprio 99
@audio - nice -10
@audio - memlock 250000

Best regards

You do not need an RT kernel to use RT scheduling. The JACK FAQ clarifies this.

@paul, you don’t need it… but i have found for MIDI sync it works better… (especially when there are multiple MIDI interfaces involved, not that I understand why… )