[LAU] Motu M64 Madi interface (not) class compliant?

[Paul Davis]

On Sat, Apr 17, 2021 at 4:22 PM Peter P. <peterparker at fastmail.com> wrote:

> * Peter P. <peterparker at fastmail.com> [2021-03-12 18:43]:
> > Hi list,
> >
> > can report that the Motu M64 Madi interface does work with a limited
> > channel count of 24 for input and another 24 for output (instead of 64
> > each). So if you are coming across a venue or employer that already has
> > one, you are good to go. Sample rate needs to be set on the device
> > before starting jack. Of course, buying the card for oneself for so much
> > money getting only one third of the channels seems useless linux users
> > IMHO.
>
> I can add now that the card does not work reliably in class compliant
> mode with external sync clocks. It will randomly switch back and forth
> output channels in banks of eight, cause clicks and distortion and
> aliasing artifacts.


The bank switching is a known problem with other MOTU USB devices, and has
been "solved" by using specific firmware releases (e.g. for the MOTU
Ultralite AVB) which may not be available anymore or for your specific
device.

I do not believe that the aliasing is caused by bank switching, but by
(possibly) an ALSA driver bug. It generally goes away within a few minutes
or on device restart.
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