PreSonus DigiMax D8 - Manual (Page 13)

OPERATION
11 | PreSonus 2007
3.2 DIGITAL CONNECTIONS AND SYNCRONIZATION
3.2.1 ADAT Optical Lightpipe
ADAT is an industry standard abbreviation for the ADAT Lightpipe protocol, which transfers eight tracks in
a single fiber optic cable. Supported sample rates are 44.1 kHz and 48 kHz.
When you are utilizing the eight DigiMax D8 preamplifiers and converting to the digital optical output,
connect one ADAT optical cable from the ADAT output on the back of the DigiMax D8 to the ADAT optical
input on your digital audio interface, workstation or digital mixer.
To synchronize your system to the DigiMax D8’s internal clock, set your other device to receive external word
clock via its ADAT optical input. You may need to consult your device’s user manual for instructions on how
to do so.
3.2.2 BNC Sync and Word Clock
When using multiple devices connected through digital audio formats like S/PDIF, AES/EBU, ADAT or
TDIF, it is necessary to synchronize them to a single word clock generator. Word clock is used to keep a
perfectly timed and constant bit rate between all synced devices to avoid data errors. A word clock generator
creates digital pulses that contain no other data (i.e. audio). These pulses clock the internal oscillators of
each device and are essential to avoid frequency drift.
A word clock signal is bundled with the audio data in the ADAT Lightpipe protocol; however, many engineers
prefer to keep word clock sync and audio separate from each other. This is where BNC word clock
connections come into play and the DigiMax D8 has a BNC word clock input for just this purpose. You will
find BNC cables used to deliver dedicated word clock in many quality studios and broadcast facilities
worldwide. BNC cables are rugged, lock into position, and can carry clock signals much farther than the
standard optical cable. A BNC word clock cable is a 75Ω, shielded coaxial cable with standard ‘twist-lock’
BNC-type connections on each end.
Please note: BNC cables are made in several impedances. The DigiMax
D8 requires an impedance of 75 Ω s to achieve consistent sync.
To synchronize the DigiMax D8 via BNC word clock, you will need to run a BNC word clock cable from the
BNC word clock output of your external device to the BNC word clock input of your DigiMax D8. From the
front panel of your DigiMax D8, select external sync using the clock button.