Specifications

SYNC I/O Guide38
From SYNC I/O Setup software utility
(Windows only):
■ Select the appropriate Digital clock reference
option from the Clock Ref pop-up menu.
If the chosen clock reference source is unavail-
able, or the current configuration is not valid,
the Locked LED on the right side of the
SYNC I/O front panel flashes.
Additional Digital Clock Information
AES/EBU The SYNC I/O AES In connector only
recognizes and uses the clock portion of an in-
coming AES/EBU audio signal. All audio infor-
mation will be ignored and will not be passed to
the SYNC I/O AES Out connector.
Word Clock Word Clock is a digital clock refer-
ence signal that runs at 1x sample rate (44.1, 48,
88.2, 96, 176.4, or 192 kHz). Pro Tools|HD-series
audio interfaces have dedicated BNC-style Word
Clock connectors. A wide variety of professional
audio devices have Word Clock connectors, in-
cluding digital mixing consoles, DASH-standard
digital multitrack tape recorders and MDMs
(modular digital multitrack recorders).
Slave Clock (256x)
Slave Clock (or Super Clock) is a Digidesign pro-
prietary clock format used by legacy Digidesign
audio interfaces (888|24, 882|20, 1622, and
ADAT Bridge) that run at 256x the sample rate.
When using legacy interfaces with SYNC I/O
and Pro Tools|HD, your master HD audio inter-
face (192 I/O, 192 Digital I/O, 96 I/O, or 96i I/O)
should supply Slave Clock to the first legacy de-
vice through its External Clock Out connector,
configured for 256x Slave Clock (see “Base
Clock” on page 58 for more information).
Pro Tools|HD-series audio interfaces are always
connected using Loop Sync (see “Clock for
Pro Tools Audio Interfaces” on page 8 for more
information).
LTC and Clock Reference
LTC can provide both positional and clock in-
formation from the same time code signal. LTC
cannot be read when the reference deck is
stopped or playing back at slow speeds, or at fast
wind speeds (roughly 10x playback speed).
Pro Tools will not lock until the LTC signal is
present.
While resolving to LTC clock, the SYNC I/O pro-
vides five options to optimize your system for
different types of tasks. This lets you choose be-
tween faster response (for when fast lock-up
time is critical), or highest sound quality (during
critical laybacks, for example).
The Session Setup window provides a sub-menu
for LTC Clock Reference choices. The five
choices provide different servo gain settings to
reduce the effects of jitter when locking to linear
time code. In Stand-alone mode, these settings
are also available from the front panel.
For additional digital clock signal informa-
tion, see “Digital Clock Signal Types” on
page 69.
Clock Reference LTC options in Session Setup