User`s guide

AUDIODESK
65
FINE-TUNING I/O TIMING
The 896HD has the ability to be sample accurate.
This means that when you transfer audio between
AudioDesk and an ADAT (or other ADAT-sync
compatible recorder), for example, you can record
the audio back and forth as many times as you want
between them and it will remain exactly at its
original sample location (unless you move it in
AudioDesk, of course).
Occasionally, you may encounter a situation in
which you observe a slight offset of one sample —
or maybe a few — caused by inherent latencies in
the devices you are using with the 896HD. Usually,
these offsets will be consistent, and you can
compensate for them in AudioDesk. To d o s o,
choose MOTU Audio System Options>Fine-tune
Audio I/O Timing from the Setup menu (Basics
menu under Mac OS 9) as shown in Figure 8-3.
Figure 8-3: Fine-tuning the timing of audio playback and recording.
SYNCHRONIZATION
AudioDesk can run under its own transport
control or slave to an external sync source, such as
SMPTE time code or ADAT sync (sample address).
Running AudioDesk under its own transport
control
If you do not need to synchronize AudioDesk with
time code or another recording device, such as a
tape deck, just leave the Slave to External Sync
command in the Studio menu (Basics menu under
OS 9) unchecked.
However, even though AudioDesk is not slaving to
external sync, you still need to be concerned with
the synchronization of the 896HD’s digital audio
clock with other devices connected to it digitally (if
any). For example, if you have a digital mixer
connected to the 896HD via an ADAT optical
lightpipe cable, you need to make sure that their
audio clocks are phase-locked. For details, see
“Syncing optical devices” on page 25 and “Making
sync connections” on page 19. If you don’t have any
digital audio devices connected to the 896HD,
digital audio phase-lock does not apply to you.
Resolving AudioDesk and the 896HD to word
clock, video and/or SMPTE time code
To resolve your AudioDesk/896HD system to word
clock, video and/or SMPTE time code using an
additional synchronization device, use the setup
shown in “Syncing word clock devices” on page 29
or “Syncing to video and/or SMPTE time code” on
page 24.
Choose Receive Sync from the Setup menu (Basics
menu under Mac OS 9) and choose the MTC
(MIDI Time Code) option. Then make sure that
the Slave to External Sync command in the Studio
menu (Basics menu under Mac OS 9) is checked.
To e n s u re t h at your audio tracks don’t drift out of
sync with your MIDI tracks — or time code, use a
hardware synchronizer like the MIDI Timepiece
AV o r D i g i t a l Timepiece to resolve the 896HD
hardware as well, as shown in Figure 3-23 on
page 29. A digital audio synchronizer is required
for drift-free SMPTE/MIDI time code sync. Make
sure the Clock Source setting in the MOTU
FireWire Audio Console window has the
appropriate setting for locking the 896HD to the
synchronizer. For example, in Figure 3-23 on
page 29, word clock is being used to resolve the
896HD, so the Clock Source setting is Wo rd Clock
In.