Ardour Crashes When Using Motu M2 as Input & Output

I’ve been able to use the MOTU M2 audio interface with Ardour on Linux, but only as an input device. If I try to use it as an output as well, Ardour crashes instantly. The crash happens after I select “M2” as the output device in the Audio/Midi Setup window, and then press “Start”. You can see the settings in the attached screenshot.

Screenshot from 2022-04-10 13-31-19

How can I use the Motu M2 as both input and output device, without crashing Ardour?
I’m fairly new to both Ardour and the Motu M2. I’ve avoided using Jack till now, as Ardour seems to recommend otherwise. My system comprises:

  • OS: Ubuntu 20.04 (linux)
  • Ardour 6.9

It could be your kernel. I came across some info describing duplex audio issues on Motu M2 and M4 devices that were resolved with kernel version 5.11. Ubuntu 20.04 shipped with an older version, so perhaps updating it would resolve your problem.

Buffersize dropdown is unset/empty?

Can you pick some buffersize 512 or 1024?

Which version of Ardour are you using?

Thanks @GuntherT , my current kernel version is: 5.11.0-27-generic. I hope that’s good enough, as updating the kernel is not straightforward on my system. However, if necessary, I can do it.

Robin @x42 , thanks too. I’m unable to select a buffer size once I’ve selected “M2” as the output option. Not sure why. Perhaps this relates to the issue. My Ardour version is:

SOLVED: I have now found a method/workaround for using Ardour 6.9 and the MOTU M2 (as input and output device) with Ubuntu 20.04.
I discovered that once the M2 was connected via USB and turned on, the OS automatically assigned it as the input and output for system audio.

In this mode, Ardour would not start. To get Ardour to start, I had to either:

  • turn on the M2 and then go to Ubuntu’s system sound settings and undo the automatic assignment of system audio input and output to the M2. I assigned them instead to the standard internal devices, i.e. internal mic and internal speakers.

  • OR: Start Ardour before turning on the M2. If I subsequently wanted to use the M2 at all, I had to turn it on, then revisit Ubuntu’s system sound settings and reassign them as above, then go to Ardour and assign the M2 as input/output/both (Ardour > Window Menu > Audio/Midi Setup).
    Screenshot from 2022-05-13 12-42-32

I have found this arrangement is highly functional for using Ardour and the MOTU M2 with Ubuntu. The downside is that all other applications are unable to use the M2 while Ardour is using it. They can use other audio input and output devices, including the standard internal ones. It seems that Ardour monopolises the M2, making it unavailable to the rest of the operating system. Only when Ardour is closed does the M2 become available again to other applications and system audio output.

That is correct, and by design when using the ALSA backend. If you want to share the audio device you need to run an audio server such as jackd or pipewire.

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