MOTU LP32 USB/AVB to 4 ADAT

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Musicmaker
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MOTU LP32 USB/AVB to 4 ADAT

Post by Musicmaker »

Has anyone tried this if this works under Linux for USB 2.0 ? (and wishful thinking AVB if anyone has a Ethernet card supporting AVB)
The spec states "1 x USB 2.0 audio class compliant " => This gives hope. Really thinking about to get this. (Even if just able to use it under Windows 10)

http://motu.com/products/avb/lp32/specs.html
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Musicmaker
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Re: MOTU LP32 USB/AVB to 4 ADAT

Post by Musicmaker »

Contacted MOTU. According to MOTU the LP32 should be able to be seen in Linux. (via USB)
The LP32 device does not support Linux nor Windows over AVB, only Mac.

It has a web/network interface, so I guess configuration changes can be made via the HTML web interface. Thus no ALSA Mixer needed.
(Not sure why they did not chose to just use MIDI Sysex to get audio and configuration over just one USB cable).

It this is true, that would be fantastic. Hope someone can try to get hold of a LP32 and try this product.
juergenmoeller
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Re: MOTU LP32 USB/AVB to 4 ADAT

Post by juergenmoeller »

I just got one and it's being recognized as a 24-in-24-out audio device in class compliant mode under Ubuntu 20.04. So it's unable to use all channels under Linux.
However, the interface doesn't work reliably. Sometimes, for some minutes, everything is fine. Otherwise, it seems to be shifting the content of the addressed channels, meaning for some minutes, sending audio out on channel 1-2 in your DAW the LP32 will act as if that was sent on channel 3-4, then after some minutes on channel 5-6, then on 7-8 ... it's super weird and I haven't ever seen anything like this. Unusable!
It also doesn't happen on Windows using the same project files (Reaper and Bitwig) and the same device settings.

It seems that MOTU's class compliant mode is kind of broken as I've found other threads describing the same behaviour on MOTU's AVB range.
juergenmoeller
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Re: MOTU LP32 USB/AVB to 4 ADAT

Post by juergenmoeller »

Tried out all available firmware versions and none of them work stable on Linux in class compliant mode. It seems that v1.3.4+169 was the last one supporting all available channels in class compliant mode, but that doesn't help if the audio isn't working at all.
I even tried it on my iPad Pro (from 2021, iOS 14) with Cubasis 3. While I can select all 24 in and outs, playback just doesn't start with the device connected. As soon as the device is gone, playback works. Class compliant mode really doesn't seem to work at all with MOTU. Have much better experience with RME devices (Fireface, Babyface).

Just found this driver. Might be worth giving a shot: https://github.com/Drumfix/motu-avb-usb
obw
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Re: MOTU LP32 USB/AVB to 4 ADAT

Post by obw »

there's a lot of discussion of Motu's AVB interfaces over in this thread.

Drumfix has indeed developed a custom driver and submitted some patches upstream - on modern kernels the custom driver should fix issues such as "channel hopping" and distortion.
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