If i understand you correctly, you're attempting to use the midi out ports to record back into the midi in ports on the same interface?
My feeling is this will not give a satisfactory or accurate result.
Trevor, I'm going to shoot you a PM. See if we can come up with a decent testing method.

John

Quote desmond:

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try repeating the test across ports 1 to 8, but reverse the tracks - ie Track 1 sending to port 8, track 2 sending to port 7, etc...

Any difference? Trying to see whether it's the processing on the AMT that's causing the difference across ports, or the order of track scanning in Logic...

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Ok just tried this. I have midi track one sending to midi port 8 on the Unitor. Midi track 2 sending to midi port 7, etc with midi track 8 sending to midi port 1.

The recorded audio tracks for the midi data showed midi track 8 sending to midi port 1, to be behind the audio recorded from midi track one + midi port 8. (the difference between the two start transients was in the region of 5.6 ms)

So higher placed midi tracks in the arrange page are given higher priority, if using the Unitor 8 mk2...... i think? Confused me a little

Quote Jauqq:

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So higher placed midi tracks in the arrange page are given higher priority, if using the Unitor 8 mk2...... i think? Confused me a little

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That was my hunch, and was certainly common place back in the day - ie when a event has to be output at any given time position, Logic has to scan down the tracks and go "Ok, we've got to send an event from track 1, let's do that, and continue to look - ah yes, there's an event on track 3 we have to send now etc.

In other words, the delay in events across the ports might be happening from Logic's end, rather than the driver itself - the driver might be correctly outputting the events where it can, it's just getting them late. (Still not a good advert for time stamping events though, of course...)

Try taking Logic out of the equation, and trying a few different DAWs sending to the U8, both in and out of port/track order, and seeing if there are any differences between apps. This should give you another set of good data to help understand the behaviour.

Quote desmond:

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That was my hunch, and was certainly common place back in the day - ie when a event has to be output at any given time position, Logic has to scan down the tracks and go "Ok, we've got to send an event from track 1, let's do that, and continue to look - ah yes, there's an event on track 3 we have to send now etc.

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Yet the Moto Express 128 does not suffer this problem, and sends all midi data simultaneously from all of it's midi ports .

The Motu time stamping driver is doing it's job correctly.

Okay... so, John and I have been trading notes offline for the last couple of days. We are both experiencing the exact same behavior with our Emagic and MOTU midi interfaces.

I have put together a video that illustrates how tight Logic can be if latencies are accounted for. Track bug not withstanding, the results are quite good in my opinion. It comes down to understanding how to work with Logic and what is going on with the midi side of things.

I think part of the reason a lot of folks value older systems is because they were not working in tandem with sample accurate virtual instruments and audio tracks. DAWs have tight timing and higher PPQ values taking away some of the inherent quantizing that can occur at low PPQ values.

Midi is never going to be perfect. You can even ague "feel" when comparing an MPC to Logic (even I kind of like the "feel" of Reason's sequencer), but, I have proven to myself that I can tighten things up in Logic to an acceptable degree.

Take a look and let me know what you think:

http://web.me.com/trevorab/Logic_Pro_9/Tight_Midi_in_Logic.html


Oh... and please forgive the crap track. I just threw this together to demonstrate/verify my settings.


Cheers,

Trevor

Here is a link to a slightly better organized page. The text is a bit of a ramble, but, it gets the point across. I will tidy up the info when I have more time.

http://web.me.com/trevorab/Logic_Pro_9/Home.html

For now, I feel we have definitely illustrated you can achieve a tight feel from Logic using the latency compensation tools provided. I am glad we have this sorted. Now, on with making music!

P.S. Thank you John for your help and input. I am glad to have this issue behind me.

excellent thread gentlemen. just wanted to thank you both for getting this research and info out there.

Cheers!