Pro Tools LE™ Latency Charts
For Digi 002® and 002 Rack™
how I ran the tests
These are the steps I followed to test for tracking latencies.
- Plugged an electric guitar directly into 1/4" input #1
- Set up two audio tracks:
- A. Input: Analog 1, Output: 1&2, panned hard left
- B. Input: Analog 5, Output: an unused bus
- Patched a 1/4 cable from monitor out Left to Analog input 5, set to +4 dBU
- Cranked up Monitor Level all the way
- Armed both tracks, got a level, made sure both tracks had the same level. The converters are low-fi enough that identical levels are not possible, but I got them as close as possible, which was +/- 0.2 dB with the electric guitar.
- Entered Low Latency Mode, recorded a few seconds of music.
- Exited LLM, set buffer to lowest setting, recorded a few seconds of music
- Set buffer to next highest, recorded a few seconds, and so on until highest buffer setting was reached.
- Changed track B output to 1&2, panned both tracks center.
- Placed a TimeAdjuster-Long plug-in on track A, and engaged invert (a.k.a. "phase") button.
- Looped each section of guitar music one at a time, finding the null point (number of samples delay where maximum signal cancellation was achieved), and entering the number of samples from the TA plug into a spreadsheet.
- Looped each section again, this time entering the corresponding number from the spreadsheet into the TA plug, and verifying that it was the correct null setting for that mode/buffer setting.
- Repeated all above for each sample rate.
- Had spreadsheet calculate ms and length figures:
- ms: divide latency samples field by sample rate/1000.
- distance: multiply ms field by 1.13 and round to whole number for feet, round down difference and multiply by 12 for inches.
by David J. Finnamore
DUC ID: daeron80
Written: April 2006
Copyright © 2006, all rights reserved