MOTU 896mk3, Руководство пользователя

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I N S T A L L I N G T H E 8 9 6 M K 3 H A R D W A R E
25
SYNCING OPTICAL DEVICES
When connecting an optical device, make sure that
its digital audio clock is phase-locked (in sync
with) the 896mk3, as explained in “Making sync
connections” on page 21. There are two ways to do
this:
1. Resolve the optical device to the 896mk3
2. Resolve the 896mk3 to the optical device
For 1), choose Internal (or any other clock source
except ADAT optical ) as the clock source for the
896mk3 in MOTU Audio Setup.
For 2), choose either ADAT Optical A or ADAT
Optical B as the 896mk3’s clock source
(Figure 3-11). Be sure to choose the optical port
that the device is connected to.
Figure 3-11: Resolving the 896mk3 to an optical device.
For details about using the clock source setting and
the MOTU Audio Setup software in general, see
chapter 5, “MOTU Audio Setup” (page 35).
Using word clock to resolve optical devices
If the optical device you are connecting to the
896mk3 has word clock connectors on it, you can
use them to resolve the device to the 896mk3,
similar to the diagram shown in Figure 3-10 on
page 24 for S/PDIF devices with word clock. Also
see “Syncing word clock devices” on page 28.
SYNCING AES/EBU DEVICES
If you would like to transfer stereo audio digitally
between the 896mk3 and another device that has
AES/EBU I/O, connect it to the 896mk3’s AES/
EBU jacks with balanced, AES/EBU grade audio
cables.
AES/EBU clock and sample rate conversion
The 896mk3 AES/EBU section is equipped with a
real-time sample rate converter that can be used for
either input or output. This feature provides a great
deal of flexibility in making digital transfers. For
example, you can:
■
Transfer digital audio into the 896mk3 at a
sample rate that is completely different than the
896mk3 system clock rate.
■
Transfer digital audio into the 896mk3 without
the need for any external synchronization
arrangements.
■
Transfer digital audio out of the 896mk3 at
double or half the 896mk3 system clock rate.
Rate conversion does not add any appreciable noise
to the audio signal (under -120 dB).
Digital audio phase lock
Without sample rate conversion, when you transfer
digital audio between two devices, their audio
clocks must be in phase with one another — or
phase-locked — as discussed earlier in “Be sure to
choose a digital audio clock master” on page 21
and Figure 3-7 on page 21. Otherwise, you’ll hear
clicks, pops, and distortion in the audio, or
perhaps no audio at all. Phase lock ensures a clean
digital audio transfer.
Another benefit of direct master/slave clocking
(without sample rate conversion) is that each
slaved device remains continuously resolved to the
master, which means that there will be no gradual