User Manual

INSTALLING THE 8PRE HARDWARE
20
SYNCING OPTICAL DEVICES
The word optical is our short-hand way of referring
to any device that connects to the 8pre via an
optical cable. An example is an audio interface with
optical connectors on it. There are many other
devices that fall into this category, including digital
mixers, digital effects processors, synthesizers and
many more.
When connecting optical devices, make sure that
their digital audio clock is phase-locked (in sync
with) the 8pre. There are two ways to do this:
■ Slave the optical device to the 8pre
■ Slave the 8pre to the optical device
Two banks of optical
The 8pre has two banks of optical connectors: a top
row and a bottom row:
Figure 3-7: Two optical banks.
When you are operating at the 1x sample rates
(44.1 or 48 kHz), use the top two connectors.
When you are operating at the 2x sample rates,
(88.2 or 96 kHz), use both sets of connectors. The
top row provides channels 1-4 and the bottom row
provides channels 5-8, as indicated by the blue
labeling on the rear panel (Figure 3-7).
Setting the clock source
In ADAT optical clock mode (as demonstrated in
the right-hand diagram below), the 8pre always
resolves to the optical input in the top row, even
during 88.2 or 96 kHz operation. So be sure to
connect the device that is the ADAT optical clock
master to the 8pre’s optical input in the top row.
Optical bank mirroring
When the 8pre is operating at the 1x sample rates
(44.1 or 48 kHz), the optical output in the bottom
row mirrors the 8-channel optical output in the top
row.
ADAT Optical IN
ADAT Optical OUT
Audio interface
or other optical
device
8pre
8pre Clock Source setting =
Internal, or any clock source
setting except Optical. The optical
device slaves to the 8pre (via its
optical cable connection).
Figure 3-6: Two setups for synchronizing an optical device with the 8pre.
8pre Clock Source setting = optical
ADAT Optical IN
ADAT Optical OUT
Audio interface
or other optical
device
8pre
With this setup, in MOTU Audio
Setup, choose the Optical clock
source setting. The 8pre slaves to
the optical device via their optical
cable connection.
!8pre Manual/Mac Page 20 Tuesday, October 12, 2010 5:52 PM