Specifications

192 I/O Guide24
To choose a clock source:
1 Launch Pro Tools.
2 Choose Setups > Hardware Setup.
3 Select a Digital Format from the enclosure
port choices: AES/EBU, S/PDIF, or Optical
(ADAT).
4 Click the Clock Source pop-up menu and se-
lect a synchronization mode. If the desired clock
is not listed, check your Digital Format setting
to be sure you have enabled the appropriate dig-
ital port and format. Choices for Clock Source
also vary depending on Sample Rate.
5 Click OK to close the Hardware Setup dialog
when you have finished.
Your choice depends on which device in your
setup you want to make the master clock device.
192 I/O can only be the clock source when it is
the master audio interface. If you choose a clock
source on another HD I/O other than the Loop
Master, Pro Tools will automatically designate
the new interface as the Loop MASTER periph-
eral, switch to it for the chosen Clock Source,
and set all other HD I/Os to Loop Slave mode.
Clock Source and Loop Master
In the Hardware Setup dialog, you can set the
clock source to be available from any HD I/O.
Choosing to use a Clock Source will, in ex-
panded I/O systems, automatically make that
I/O the Loop Master. The LOOP MASTER LED
will light on the front of the Loop Master I/O.
Because any HD I/O can be the Loop Master,
you can use any of the digital ports on any HD
I/O as your system clock source.
Digital Format
The Digital Format section enables you to
choose which port the 192 I/O will use for digi-
tal audio input and/or word clock input. For ex-
ample, to record digitally from an optical S/PDIF
device connected to the Enclosure Optical In
port, enable the Optical (S/PDIF) option for Dig-
ital Format. Only one digital input port can be
used at a time, although the AES/EBU and
S/PDIF outputs are mirrored at all times.
Clock Source
The Clock Source selector lets you choose
among available digital clock choices to deter-
mines which HD-series interface, and which
specific digital port on that interface, is provid-
ing clock to Pro Tools. Choices will include 1x
Word at the session sample rate or base rate (for
clocking to house video reference or other Word
clock signals connected to the External Clock In
port), and other choices as appropriate for the
currently enabled Digital Format and sample
rate.
Pro Tools will remember your configuration un-
til you change it. If you want to change your
Pro Tools hardware configuration in the future,
you can access these parameters again in the
Hardware Setup dialog.