Hi - WARNING - LOTS OF RAW TIMING MEASUREMENTS MEASURED IN SAMPLES AHEAD!

There is a lot of posting on the Cubase forum about MIDI timing (most lately in the "early MIDI in VSTi's" thread), and so I wanted to test my own system. I have a pre-built computer from a reputable company, though getting a bit long in the tooth (the computer). I came up with some hard #s, but I'm not really sure how to interpret them, specifically, are these what is to be expected with the average DAW? ... or are these really not up to snuff at all?

I did 2 sets of measurements, the 1st simply measuring the difference in timing between when the audio from my hardware synth was printed relative to the MIDI in.

The second set of measurements were similar, but with a VSTi loaded up - here, as before, I measured when the direct audio from the hardware synth and the MIDI data were printed; I also measured when the VSTi audio was printed (when routed from a group).


Here are my specs:
Cubase 6.0.5 (32-bit), XP SP2, Seagate Barracuda 80/160/160GB; Intel 550 Pentium 4 3.4GHz, 2GB RAM, HT+; Intel D915PBL mobo; Dual Radeon ATI X300SE 128MB video; Delta 66 in Omni I/O Studio; Motif8 hardware synth


Here is how I ran the test:
-44.1KHz. 256 sample buffer.
-Audio beats for metronome (not MIDI clicks).
-Headphones!
-Windows MIDI driver, with "Use System Timestamp" checked
-Cubase 6.05 is 32-bit.

Here's what I did:
Played Motif Synth into Cubase, one note per audio metronome beat:
a) audio cables DIRECTLY into my interface, and
b) Midi via USB.

For the testing with the VSTi loaded, I also had:
c) Motif MIDI > VSTi (Halion Sonic SE) > Group > VSTi Group Audio
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Here are the testing results without the VSTi (simply the Motif sending Audio and MIDI to Cubase):

MIDI --47-- samples BEFORE Audio
MIDI --25-- samples BEFORE Audio
MIDI --24-- samples BEFORE Audio
MIDI --83-- samples AFTER Audio
MIDI --38-- samples AFTER Audio
MIDI --16-- samples AFTER Audio
MIDI --21-- samples AFTER Audio
MIDI --32-- samples AFTER Audio
MIDI --28-- samples AFTER Audio
MIDI --7-- samples AFTER Audio
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Therefore, MIDI was printed an average of 13 samples AFTER Audio was printed, when no VSTi was loaded up. The largest amount of time difference was just under 2 msec (83 samples at 44.1K).

So, my question is ...: Is this "OK"? Or is "sample accuracy" the expected standard? I think I understand from this article ( http://www.soundonsound.com/sos/dec07/articles/cubasetech_1207.htm ) that sample accuracy isn't going to happen , perhaps it's due to jitter or something else, but whatever the reason, there is up to a 2 msec difference. Is that enough to cause "phasiness" or other artifacts if things are played together? I have noticed phasiness when I play/record live ... I can live with that ... but what about when mixing - should I be shifting tracks by 10 or 20 or 80 samples before I get down to it?
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Here are the testing results with the VSTi loaded:

MIDI printed---9--samples before "Direct Audio" and --500-- samples before VSTi>Group>Audio

MIDI printed--40--samples before "Direct Audio" and --370-- samples before VSTi>Group>Audio

MIDI printed---2--samples before "Direct Audio" and --475-- samples before VSTi>Group>Audio

MIDI printed--62--samples AFTER "Direct Audio" and --515-- samples before VSTi>Group>Audio

MIDI printed--58--samples AFTER "Direct Audio" and--365-- samples before VSTi>Group>Audio

MIDI printed--19--samples before "Direct Audio" and--425-- samples before VSTi>Group>Audio

MIDI printed-113--samples AFTER "Direct Audio" and--275-- samples before VSTi>Group>Audio

MIDI printed--74--samples AFTER "Direct Audio" and--455-- samples before VSTi>Group>Audio
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Therfore, MIDI was printed an average of 30 samples AFTER audio was printed directly from the Motif (i.e., audio out of Motif > audio into interface), when a VSTi was loaded. This is similar to the 14 samples that the MIDI was "late" compared to the direct audio when a VSTi was not loaded, but the variation seemed higher here. Is the increased variability in this situation just random? I don't know. Should I be concerned about the higher variability in MIDI timing when a VSTi is used any more than when it isn't?

Finally, for what it's worth, The MIDI was printed (on the average) --423-- samples before the VSTi>Group>Audio was printed. Doing the math, the audio recorded directly from the Motif was printed (on the average) about --453-- before the VSTi>Group>Audio was. This is just under twice my buffer setting, for what it's worth.

Thanks for any perspective on these questions. I can crunch #s, but as far as what is important ... I'm so grateful for the experts on this forum!!

Thanks -

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Alexis -Cubase 6.5.0/SX3.1.1.944, XP SP2, 4GB RAM (1GB not accessible, but used just to balance the computer so it doesn't tip over); Delta 66 in Omni i/O Studio; Motif8; UAD-1

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