On Fri, May 12, 2017 at 10:03 PM, Fernando Lopez-Lezcano <nando@ccrma.stanford.edu> wrote:
On 05/11/2017 12:17 PM, Moshe Werner wrote:


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.

Thanks for the tips. I just got the interface last week and am still learning it and how it works with my laptop. 

 
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).

That's great news that AVB is working on linux too! 
Could you elaborate on the connection scheme of your setup? Are the different Motu boxes connected via the AVB switches? 


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.

Had the same issue! Thanks for pointing that out. 
Basically I couldn't explain why at first Jack doesn't launch and then suddenly everything is ok:)

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

That's also great news!
 

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 :-(

That's not so great news:( 
Why get it right just to do it all wrong again...?