New MOTU Hardware!

[bayswater]

Looking over the material in the manual, I'm wondering if we should expect to see AVB drivers that would allow us to run instances of audio application on multiple computers and have them all linked with low latency via an AVB switch over ethernet, without the need for audio interfaces on every computer? Is that something AVB is meant to do?

[EMRR]

It certainly appears so. I tried to put it through the wringer with my limited test abilities, and I didn't see anything that said 'no'.

[bayswater]

Well that makes AVB a very significant protocol. It would move a Mac Pro or high end PC off my list of future equipment. A network of smaller cheaper computers that sum to the processing requirement is all I'd need.

[EMRR]

I was able to do some comparisons in Spectrafoo Complete, looking at 2408mkIII and 16A, measuring a simple output to input loop against the internal signal generator.

16A loop noise is 10-12 dB lower than 2408mkIII loop noise as far as averages go, and the 16A PSU is close to invisible compared to the 2408mkIII which has easily visible power harmonic spikes at much higher than average level. This seems to confirm what my ears experienced in tracking sessions so far, a deeper bottom with clearer very low level detail.

16A noise profile remains constant across the comparable frequency range for all sampling rates, meaning that the lower rates appear to just chop cleanly along the same line as the higher rates.

2408mkII noise profile shows a noise shaping boost near upper cutoff, so the boost rises earlier at lower rates.

16A has more linear bass, -0.01 dB slightly under 8Hz relative to 1K, 2408mkIII is more like -0.2 down at the same spot.

The upper response is microscopically different between the two units, the pretty pictures look obviously different when the measurement scale is very very tiny. You could call it significant if you were ignoring the scale and frequency.

Phase response is possibly more significant visually, who knows what the ear says about it. The 16A is more linear at the very bottom, as one would assume based on the freq response. The upper phase response deviation is mostly comparable, but opposite in direction. So not comparable? This is really the biggest difference after noise. Deviation from zero is roughly comparable, but the 2408mkIII swings positive while the 16A swings negative. The 2408mkIII has a smooth phase curve, while the 16A has a wavy phase curve, which I would attribute to differences in the low pass filter schemes employed.

If I were picking the best rates based on phase with the 16A, I'd choose 88.2 or 192. 96 and 176.4 aren't as phase linear, but still clearly beat the snot out of 44.1 and 48.

The 2408mkIII appears more phase linear closer to cutoff at 88.2 and 96, but I think noise performance trumps this comparison. 2408mkIII phase looks equally snotty at 44.1 and 48K.



The coolest possibility I saw tech support mention over at GS was investigations into streaming audio to/from the computer over CAT6, maybe freeing up all computer TB and USB ports.

[bayswater]

The coolest possibility I saw tech support mention over at GS was investigations into streaming audio to/from the computer over CAT6, maybe freeing up all computer TB and USB ports.

This is the what I want to look into. I had a look over at GS but couldn't find it. Can you post a link?

[EMRR]

It's in mrrmiller's long posts. I pretty much paraphrased him entirely, no real info or solid promises, just that it's under investigation.

[HCMarkus]

Can you post a link?

http://www.gearslutz.com/board/music-co ... t=motu+avb

[bayswater]

Thanks. I guess a pure ethernet connection is not immanent, at least not from MOTU.

[HCMarkus]

Thanks. I guess a pure ethernet connection is not immanent, at least not from MOTU.

Yes, but since MOTU's future in higher-end pro audio interfaces hinges on the success of this new line, development on the software side will certainly continue for some time. And that will, hopefully, include direct ethernet <> computer connectivity.

[bayswater]

Thanks. I guess a pure ethernet connection is not immanent, at least not from MOTU.

Yes, but since MOTU's future in higher-end pro audio interfaces hinges on the success of this new line, development on the software side will certainly continue for some time. And that will, hopefully, include direct ethernet <> computer connectivity.

I have no doubt they will; it's the timing I'm wondering about. There are also some specifics about using Ethernet to connect an AVB interface to a computer, versus using the general AVB protocol to connect computers to each other without the use of an interface except for a master out D-A for monitoring. I expect MOTU would be more interested in the former.

But it seems many of us use more and more sounds that originate inside a computer, and need CPU horsepower, maybe in the form of several ethernet switched CPUs, and not so many interface I/O channels.

[EMRR]

In DP8, the Input Monitoring Mode option for 'direct hardware playthrough' is not available with the 16A. I'm curious why this can't be implemented, or if it might be coming in an update.

[EMRR]

A graphical follow-up to my measurement description above.


Noise floor comparisons of MOTU 16A and MOTU 2408mkIII, scale is 0dBFS relative.
192K/176K/96K/44K. Lower group is the 16A.

This one more clearly shows the PSU related noise in the 2408mkIII.

Phase comparisons. Upward curves are 2408mkIII, downward are 16A.

16A responses and phase at 192K/176K/96K/44K.

Upper frequency response comparisons of MOTU 16A and MOTU 2408mkIII. 176K isn’t shown.

Lower frequency response comparisons of MOTU 16A and MOTU 2408mkIII. Oranges/Yellow/Red are the 16A, white is the 16A at 192K, Blues/Green/Purple are the 2408mkIII.

Some more numbers:

600 ohm output signal gen sending +24dBu reads 23.7dBm at outputs with multimeter, -0.25 dBFS incoming to 16A set input trim 0.
16A output set 0 (max), output reads +21.7dBm with multimeter.

Impossible to get same analog output level as analog input level without DSP gain. Restated, the input has greater headroom than the output. This agrees somewhat with the manual specs, I'm wondering if there's a typo there since I am seeing higher output levels than the listed max.

16A noise numbers as seen on the plots above:
60Hz (AC line) -147dBFS
125Hz -154dBFS
250Hz -151dBFS
715Hz spike about -140dBFS (certainly looks higher on the plot, but zoom in confirms)
1kHz -147dBFS (note the manual states in or out THD+N of -110 dB, -1dBFS, unweighted, 1kHz)
4kHz -143dBFS
16kHz -137dBFS

Spectrafoo code stream appears to be 24 bit, with Audio/MIDI describing 32bit float and DP8 set for 32bit float recording.

[EMRR]

I got a pop-up in the control app about an update to the 16A, which requested I connect an ethernet cable to receive the update. I was connected with TB at the time, very curious why ethernet would be a requirement here. I don't see that spelled out anywhere in the wording of the support literature.

EDIT----answer:

We designed the firmware update to work over ethernet mostly for convenience. If you're a user with lots of networked boxes, you can upgrade them all from a distance (even over wifi!) without having to plug in directly and without having to download or run an updater application.

We also decided on this approach for engineering reasons. We put a heavy emphasis on reliability. When installing an update, the device reboots into a stripped-down recovery partition to guarantee that you can always finish updating, even if the power goes out mid-update. Since updates can also affect the Thunderbolt or USB chips, we can't use them from the update mode.

[EMRR]

Tonight I tracked a 2 gtr/bass/drums band that I've recorded twice previously, 16 live inputs.

The 16A still continues to sound a large step up from what I've heard coming out of 24i/o's and 2408mkIII's. The additional analog headroom is also really nice.

[EMRR]

....and they just added 24Ai and 24Ao units to the line. I don't see prices anywhere yet.