Apogee Digital X-HD - Manual (Page 13)

APOGEE ELECTRONICS
3
X-HD card – User’s Guide
Connecting X-HD Equipped Apogee Interfaces
Clock Connections
Apogee has conducted considerable
research on the clocking of digital
systems, resulting in the development and
production of our Big Ben Master Clock.
With vanishingly low jitter and enough clock
outputs to connect several slave interfaces
directly to one master, Big Ben is always the
best solution for clocking any digital system,
including X-HD equipped Apogee interfaces.
Figure A. Optimum clocking configuration using BIG BEN
In lieu of Big Ben, we recommend
connecting the master device’s clock
output to the slave devices using BNC “T”
connectors as illustrated in the connection
diagrams shown to the right. Terminate the
last Word Clock input with a 75 ohm load
Figure C. NOT RECOMMENDED!
We recommend against any clocking
scheme where the clock output of one
device is connected to the clock input of the
next, that unit’s clock output is connected
to a third’s clock input, and so on. By thus
“reclocking” at each interface, additional
phase lock loops (PLLs) are introduced
into the clock chain, resulting in the
accumulation of jitter.
Figure B. Correct clocking configuration to the master device’s
clock output using BNC “T“ connectors