User Manual

HD I/O Guide6
Loop Master LED
The LOOP MASTER LED indicates which
Pro Tools audio interface is the master Pro Tools
peripheral. The Loop Master LED will be contin-
uously lit on the current Loop Master peripheral
only, and unlit on all other peripherals. (Only
one Pro Tools audio interface can be Loop Mas-
ter at a time.) The Loop Master LED will always
be lit with a single interface.
For Pro Tools|HD systems, Loop Master defaults
to the first Pro Tools audio interface connected
to the Pro Tools|HD Core card.
Sync Mode LEDs
The SYNC MODE LEDs indicate the current
Clock Source as set in Pro Tools.
INT (Internal) Indicates the HD I/O sample clock
is generated by its internal clock, as determined
by the session Sample Rate.
DIG (Digital) Indicates that an external AES/EBU,
TDIF, Optical (ADAT), Optical (ADAT S/MUX),
or S/PDIF device is providing system clock. If no
valid clock source is detected, HD I/O will
switch to internal clock, the DIG LED will flash,
and an error message will appear on-screen in
Pro Tools.
LOOP Indicates that the HD I/O is slaving to an-
other Pro Tools|HD audio interface using Loop
Sync.
EXT (External) Indicates that the HD I/O is using
the EXT CLOCK IN port for system synchroniza-
tion.
When synchronized to Word Clock, External
Clock input and output do not have to be at the
Word Clock rate. EXT CLOCK IN synchroniza-
tion will typically be 1x the current session sam-
ple rate. However, for sample rates higher than
48 kHz, HD I/O generates a choice of 1x, 2x, or
4x of a base rate of 44.1 kHz or 48 kHz, as
follows:
Meters
These four-segment LEDs indicate signal level
for each of the sixteen channels. The top row
of meters indicates input levels, and the bottom
row shows output levels. These meters are
calibrated at –42 dB, –18 dB, –6 dB, and 0 dB,
respectively.
Session Sample Rate Word Clock Support
44.1 kHz 44.1 kHz
48 kHz 48 kHz
88.2 kHz 88.2 kHz
44.1 kHz
96 kHz 96 kHz
48 kHz
176.4 kHz 176.4 kHz
44.1 kHz
192 kHz 192 kHz
48 kHz
Note that 0 dB is not to be confused with
clipping; use the on-screen meters in
Pro Tools to determine whether a signal is
clipping.