Avid HD OMNI Preamp, I/O, and Monitoring Pro Tools HD Series Interface - Manual (Page 25)

Chapter 3: Connecting HD OMNI 21
Connecting Loop Sync
If you are using two (or more) Pro Tools audio interfaces or a SYNC peripheral, Loop Sync must be
connected to maintain proper clock among the devices. For an example of multiple audio interfaces,
see Figure 2 below. (For examples that include a SYNC peripheral, see the
SYNC HD Guide. )
To make Loop Sync connections:
1 Connect the Loop Sync Out of each interface to the Loop Sync In of the next interface with BNC
cables (included with each audio interface).
2 Connect the Loop Sync Out of the last interface to the Loop Sync In of the primary interface.
Figure 4. HD OMNI connected to the DigiLink Mini Port 1 on a Pro Tools|HD Native card, with an HD I/O connected
to its Expansion port. A second HD I/O is connected to the DigiLink Mini Port 2 on a Pro Tools|HD Native card, with
a third HD I/O connected to its Expansion port. Loop Sync (BNC) cables connect the HD OMNI and all three HD I/Os.
POR
T 1
POR
T 2
12-foot DigiLink Mini
Pro Tools|HD Native card
cable
Loop Sync
18-inch DigiLink
Mini cable
cables
HD OMNI
HD I/O
HD I/O
HD I/O