Specifications
Chapter 3: Installation Overview 17
For example, to record digitally from an optical
S/PDIF device connected to the Enclosure Opti-
cal In port, enable the Optical (S/PDIF) option
for Digital Format.
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 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 cur-
rently 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. Hardware Setup config-
urations are stored globally rather than by ses-
sion.
You will be able to select the sample rate each
time you create a new session.
SYNC MODE Indicators
The SYNC MODE LEDs indicate the current
clock source.
INT (Internal) This is the 192 Digital I/O stan-
dard clock setting. In this mode, the
192 Digital I/O sample clock is generated by its
internal crystal oscillator, as determined by the
session Sample Rate.
DIG (Digital) This setting indicates that an exter-
nal AES/EBU, TDIF, Optical (ADAT), or S/PDIF
device is providing system clock. If you want to
use an AES/EBU or S/PDIF device as Clock
Source, you will have to select the correspond-
ing Digital Input format. If no valid clock source
is detected, 192 Digital I/O will switch to INT,
the DIG LED will flash, and an error message
will appear on-screen in Pro Tools.
To record from an AES/EBU source, select
AES/EBU for Digital Format and make sure it is
selected as Clock Source.
To connect digitally with other digital devices
that are functioning as more than an input de-
vice (such as when sending and returning sig-
nals to and from an external digital signal pro-
cessing device) be sure to set the external digital
device to external clock. This will allow the ex-
ternal digital device to clock off the digital out-
put port you are using on the 192 Digital I/O.
The 192 Digital I/O can function in this way
while in Internal clock mode, or could use a
third device as Clock Source.
Front panel synchronization mode setting LEDs
You will not be able to use the Optical
(ADAT) port as an eight-channel synchroni-
zation source if the radio button for Optical
S/PDIF is selected. Likewise, you must first
select the radio button for Optical S/PDIF in
the Digital Format section if you want to use
the Optical (ADAT) port to synchronize to re-
ceive Optical S/PDIF (also known as TOS-
Link, it supports sampling rates up to
96 kHz).