24-Bit Operation; Fine-Tuning I/O Timing - MOTU 828mkII User Manual

For example, if you are using analog only, you only
need 12 channels. If you are using analog and RCA
S/PDIF, you need 14 channels.
As another example, if you are using analog, RCA
S/PDIF and ADAT optical, you need 22 channels
(the maximum number of simultaneous output
channels provided by the 828mkII).
WORKING WITH 828MKII INPUTS AND
OUTPUTS
Once you've enabled the MOTU FireWire Audio
driver as explained earlier in "The 828mkII
settings" on page 66, 828mkII audio inputs and
outputs will appear in AudioDesk's audio input and
output menus. If you don't see the optical inputs
and/or outputs, check the MOTU FireWire Audio
Console to make sure they are turned on and set to
the format you require. If you don't plan to use the
optical input or output, turn it off to conserve
computer bandwidth.
Phones 1-2
If you've chosen to treat the 828mkII headphones
as an independent output, you'll see Phones 1-2 in
AudioDesk's output menus. Audio tracks assigned
to this output pair will be heard on the headphone
jack only. For further explanation, see "Phones" on
page 67.
Mix1 1-2
In AudioDesk's audio input menus, you'll see an
828mkII input called Mix1 1-2. This input source
delivers the output of CueMix DSP "MIX1" (the
first mix bus of the four on-board no-latency
monitor mixes in the 828mkII) back to your
computer. This input serves, for example, as a
convenient way for you to record the 828mkII's
MIX1 monitor mix back into AudioDesk (for
reference and archiving purposes). Further, if you
are sending audio from AudioDesk to the same
output pair as MIX1, you can choose to either
include or exclude the audio from the computer in
68
the stream being sent back to AudioDesk. For
details on how to do this, see "Mix1 Return
Includes Computer" on page 100.
☛
Warning: the Mix1 1-2 input can cause
feedback loops! DO NOT assign this input to a
track that shares the same 828mkII output pair as
MIX1.

24-BIT OPERATION

Your 828mkII hardware fully supports
AudioDesk's 24-bit recording capabilities,
including both analog and digital 24-bit recording.
If you would like to record and play back 24-bit
audio files, go to the Setup menu (Basics menu
under OS 9), choose MOTU Audio System
options>Configure Sample Format, and choose
24-bit recording as the sample format. This setting
is saved with the AudioDesk project.

FINE-TUNING I/O TIMING

The 828mkII 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 828mkII.
Usually, these offsets will be consistent, and you
can compensate for them in AudioDesk. To do so,
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 9-3.
A U D I O D E S K