Syncing Word Clock Devices; Syncing To Smpte Time Code (Ltc) - MOTU 828es User Manual

For A, choose Internal (or anything other than
Optical) as the clock mode in the Device tab (item
#13 on page 12). Then configure the other device
to resolve to its optical input.
For B, choose Optical as the clock mode (item #13
on page 12), and configure the other device to
resolve to its own internal clock.
For C, choose Word Clock as the clock mode for
the 828es (item #13 on page 12), and resolve the
other device to its word clock input.
Using word clock to resolve optical devices
If the optical device has word clock connectors on
it, you can use them to synchronize the device
with your MOTU interface. See "Syncing word
clock devices" on page 48.

SYNCING WORD CLOCK DEVICES

The word clock connectors on your MOTU device
allow you to synchronize it with a wide variety of
other word clock-equipped devices.
For standard word clock sync, you need to choose
an audio clock master (as explained in "Be sure to
choose a digital audio clock master" on page 47).
In the simplest case, you have two devices and one
is the word clock master and the other is the slave
as shown below in Figure 5-20 and Figure 5-21.
Master
Word clock OUT
Word clock IN
Slave
Figure 5-20: Slaving another digital audio device to your MOTU device
(an 828es in this example) via word clock. For the 828es clock source,
choose any source besides word clock, as it is not advisable to chain
word clock.
48
Audio
clock
Master
Slave
Figure 5-21: Slaving your MOTU device (an 828es in this example) to
word clock. For the 828es clock source, choose 'Word Clock In' .
Daisy-chaining word clock
If necessary, you can daisy-chain several word
clock devices together. When doing so, connect
WORD CLOCK OUT from the first (master)
device to the WORD CLOCK IN on the second
device. Then connect its WORD CLOCK THRU
port to the next device's WORD CLOCK IN port,
and so on. On your MOTU interface, use its
WORD CLOCK OUT port and change its
operation from OUT to THRU in the Device tab
of the MOTU Pro Audio Control web app (item
#15 on page 12).
If you have more than four word clock devices that
you need to synchronize, avoid chaining their
word clock connections. Instead, use a word clock
distribution device of some kind.
Word clock is not needed for AVB networking
When working with multiple MOTU interfaces on
an AVB network, synchronization is handled by
AVB, so no word clock connections are necessary.
828es
See the next section for details.

SYNCING TO SMPTE TIME CODE (LTC)

The Clock Mode menu (item #13 on page 12)
provides the ability to resolve to SMPTE time code
Other device
(Longitudinal Time Code, referred to as LTC) from
any specified analog or digital input.
When you choose the LTC clock mode setting, the
audio phase lock engine in your MOTU interface
resolves to the incoming time code. (See below for
how to specify the time code input.) This ensures
that audio passing through the interface remains
Word clock master device
Word clock OUT
Word clock IN
H A R D W A R E I N S T A L L A T I O N
828es