Specifications

Chapter 2: 192 Digital I/O Overview 7
S/PDIF Digital In and Out
These are an additional pair of unbalanced, two-
conductor RCA jacks that accept and output a
stereo S/PDIF digital data stream. S/PDIF sup-
ports up to 24-bit audio, at sample rates up to
96 kHz. To avoid RF interference during S/PDIF
transfers, use 75-ohm coaxial cable.
Optical (ADAT) In and Out
These Optical ports can be configured to func-
tion as two channels (stereo) Optical S/PDIF or
as a third set of eight channels of Optical
(ADAT) input and output.
In Optical S/PDIF mode, these ports support
two-channel Optical input and output at sam-
ple rates up to 96 kHz. In Optical (ADAT) mode,
sample rates above 48 kHz are not supported;
unlike Optical (ADAT) ports on the Digital I/O
cards, these Optical (ADAT) do not feature real-
time sample rate conversion.
LOOP SYNC In and Out
Loop Sync is a dedicated clock loop for synchro-
nizing multiple HD-series interfaces together.
Loop Sync uses a word clock signal based on
sampling rates of either 44.1 kHz or 48 kHz. As
sample rates increase in the system, Loop Sync
continues to operate at a base rate of 44.1 kHz or
48 kHz, depending upon the higher rate.
The Loop Sync In and Out ports are standard
BNC connectors that output a 1x Loop Sync
clock signal. Loop Sync should only be used to
chain multiple HD-series peripherals together.
EXT. CLOCK In and Out
The External Clock I/O ports are standard BNC
connectors that receive and output word clock.
These ports can be used to synchronize the
192 Digital I/O with any word clock-capable de-
vice.
The External Clock In port is configured by your
choice for Clock Source in the Hardware Setup
dialog. The External Clock Out is configured us-
ing the External Clock Out selector in the Hard-
ware Setup dialog.
AC Power
This connector accepts a standard AC power ca-
ble. The 192 Digital I/O is auto power-selecting
(100V to 240V) and will automatically work
with a standard modular cable to connect to AC
power receptacles in any country.
Primary DigiLink
This port is the main audio connection between
the 192 Digital I/O and Pro Tools. The Primary
DigiLink port supports 32 channels of I/O, 16 of
which are routed directly to and from the Ex-
pansion or Legacy ports. See “Guidelines for
DigiLink Connections” on page 9.
Expansion DigiLink
The Expansion port lets you attach an addi-
tional HD-series I/O to the 192 Digital I/O. This
port passes channels 17–32 to the secondary, or
Expansion, I/O.
Because crucial timing data is passed
through the Loop Sync and Word Clock ports,
you should use high-quality, 75-ohm RG–59
cables for making connections.