[LAU] Motu 1248 - Full success

Fernando Lopez-Lezcano nando at ccrma.Stanford.EDU
Fri May 12 20:03:34 UTC 2017

On 05/11/2017 12:17 PM, Moshe Werner wrote:
> Hi Folks,
> So I got a pretty good deal on a Motu 1248 and went for it.
> Here are my first impressions from half a day of testing.
>  First and foremost, the interface just works! Out of the box. I plugged
> it in configured Jack and got sound. Great... and non trivial for Linux.
> After a bit of fiddling around with my Network settings I got the
> control software to work, and I must say it's just amazing to have a
> piece of equipment that I can fully use under Linux.
> There is a full featured mixer in the DSP that's also a nice addition,
> but the main thing for me was the routing matrix, which is pretty cool
> to have.

Yes, this is very nice and gives access to all the configuration switches.

> Latency - The latency in CC mode is better than my Firewire interface,
> but still a bit worse than the rme. For now I succeded to run a medium
> session (25 Channels with processing and fx) at 64 frames buffer size
> with 3 buffers.
> Certainly not bad. While playing guitar and singing I didn't feel any of
> this annoying delay that you sometimes get when the latency is bad.

Make sure you are running threaded irq's and that the irq that handles 
the usb connection is running with "soundcard priority". That helps a 
lot (maybe you are already using rtirq and is doing that for you). And, 
if you can, make that the only device that is attached to that 
particular usb hub.

> Sound quality - Pretty good. I have nothing to complain about... Though
> I can't really hear the supposedly amazing ESS converters stand out from
> the other professional DAC crowd...
> To be honest in the Studio I'm working happily with the old Alesis
> HD24xr AD/DC to make 1/0 out of my precious electrons...
> The Preamps are pretty clean sounding from my firswt impression, but I
> really didn't have enough time to toy with them.
> The channel count is huge for my terms. 64 in and out... That should be
> enough for me. Though I didn't get around to check if the AVB connection
> does really work on Linux.

I have never had the time to try to make the whole AVB thing work. 
Trying OpenAVB a while back I managed to get the Motu to sync with the 
Linux box through AVB, but never went as far as getting discovery and 
streaming working (no time). You do need an ethernet interface that has 
AVB support (Intel i210, for example).

On the other hand I'm working on a big system that uses (for now) USB at 
44.1/48 with a 64 channel count to interface with computers, and then 
the rest of the I/O going through AVB streams to and from additional 
boxes (I use either an A16 or 24ai as entry points because they support 
8 i/o AVB streams). Pretty neat with all the routing matrices shuttling 
samples back and forth. You have to pay attention to how many AVB 
streams each card can handle (they are not necessarily symmetric).

> To summarize I'm feeling that we are moving in the right direction here...
> I hope other manufacturers will follow and make Interfaces and software
> that work with Linux...

I found one issue when using Jack. When you use the interface for the 
first time, or when changing sampling rates, the interface takes up to 7 
seconds to actually change sampling rate and get in sync with others or 
itself. During that time Jack will not start successfully ("cannot set 
hardware params"). The trick so far is to be patient, wait the required 
time, try again and things just work.

The A16 works, as well as the 24ai and 24ao.

I had problems with the newer generation of Motu cards that have a USB3 
interface, so beware. Those work fine with USB2 connections but then the 
I/O is restricted to 24 channels input and output (in the older 
generation and with the latest firmware you can select whether you have 
more channels and less sampling rate options or visceversa - that is not 
available in these new cards). If you connect to an USB3 port the USB 
subsystem in the kernel hangs or gets really confused. Reboot time :-(

-- Fernando

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