Avid Technology Pro Tools SYNC HD, Manual

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Pro Tools | SYNC HD Guide 52
To configure Pro Tools tracks for Fader Start Play
and Stop:
1
Use the New Track dialog to create two new
auxiliary input tracks. If you already have Aux-
iliary Input tracks, you will use the first and sec-
ond (top-most in the Edit window, left-most in
the Mix window).
2
When the first visible Auxiliary Input track in a
Pro Tools session is above –120 dB, GPI Relay
output 3 (Fader Start #1) will be enabled; other-
wise, it will be disabled.
Similarly, when the second visible Auxiliary
Input track in a Pro Tools session is above
–120 dB, GPI Relay output #4 (Fader Start #2) will
be enabled; otherwise, it will be disabled.
If you rearrange channel strips in the Pro Tools
Mix or Edit windows, the two GPI outputs will up-
date dynamically to reflect the current state. The
Fader Start channel must be in a Show Track state
(not hidden). See “GPI Relay Wiring for Fader-
Start” on page 79 for additional GPI information.
Calibrating the SYNC HD
Oscillator
SYNC HD provides a feature for calibrating the
frequency of the onboard crystal oscillator. This
allows the SYNC HD to be used as an extremely
accurate frequency reference while in Inter-
nal/VSO mode.
With normal usage, the SYNC HD should never
require recalibrating. Each unit is factory cali-
brated to /– 5 ppm (parts per million).
You may want to recalibrate a SYNC HD in the
following situations:
• If greater than 5 ppm accuracy is required.
• If the unit needs to be matched to a unique (non-
standard) frequency.
• To precisely compensate for component aging.
• To restore the original factory setting.
Oscillator Resolution and Stability
The unit of calibration for SYNC HD is 1/64th of a
sample period. What this means is that a
SYNC HD can theoretically be calibrated to about
1/3 ppm (0.33 part per million). The unit will
maintain calibration across a wide range in tem-
perature. Long-term drift should be less than
1 ppm per year due to aging of the crystal. To put
this in perspective, most digital audio products are
accurate to within 20 to 50 ppm and drift with tem-
perature. This level of accuracy is possible because
SYNC HD contains a low-jitter, high-stability
temperature- controlled crystal oscillator.
Warm Up the SYNC HD Before Recalibrating
Before you begin the calibration procedure, power
on the SYNC HD and allow it to warm up for at
least five minutes. The temperature of the room (or
chassis) isn’t critical during the calibration proce-
dure. However, if you need better than 3 ppm ac-
curacy, it is recommended that you allow the
SYNC HD to warm up for at least 30 minutes and
that the chassis be at normal operating tempera-
ture.
The original Oscillator Calibration value is printed
on the factory sticker, on the SYNC HD bottom
panel.
Oscillator recalibration does not occur
during firmware updating or when resetting
the SYNC HD to factory defaults (see “Re-
storing Factory Settings” on page 53).