MOTU PCI-424, User Manual

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M O T U P C I A U D I O C O N S O L E
65
The
clock source
determines the digital audio clock
that the PCI-424 system will use as its time base.
For a complete explanation of synchronization
issues, see “Make sync connections” on page 37.
The following sections briefly discuss each clock
source setting.
PCI-424: Internal
Use the PCI-424: Internal setting when you want
the PCI-424 system to operate under its own digital
audio clock. For example, you may be in a situation
where all you are doing is playing tracks off hard
disk in your digital audio software on the
computer. In a situation like this, you most often
don’t need to reference an external clock of any
kind. For example, you might simply be playing the
hard disk tracks and mixing them to the analog
outputs of your MOTU audio interface. In this
case, no other digital audio clocks are involved.
Another example is transferring a mix to DAT. You
can operate the PCI-424 system on its internal
clock, and then slave the DAT deck to the PCI-424
system, either via the SPDIF connection (usually
DAT decks slave to their SPDIF input when you
choose the SPDIF input as their record source) or
via the word clock output of your MOTU PCI
audio interface (if your DAT deck has a word clock
input).
PCI-424: ADAT
ADAT refers to the ADAT Sync digital audio
synchronization format. It allows the entire
PCI-424 system to slave to the ADAT sync chain
connected to your PCI-424 audio card (via the
9-pin connector on the card). ADAT sync also
carries precise, sample location information,
which allows sample-accurate software to transfer
audio to and from ADATs without drifting by as
much as one sample.
Use this setting when you are using the PCI-424
system with one or more ADATs or other ADAT
Sync-compatible devices. Make sure the PCI-424
card is connected to the end of the ADAT sync
chain.
You should also use this setting if you have a
MOTU MIDI Timepiece AV or Digital Timepiece
universal synchronizer, which allows you to drive
your entire system from the transport controls of
your audio software.
PCI-424: SMPTE
Choose this setting to resolve the PCI-424 card
(and all connected interfaces) directly to SMPTE
time code (LTC) being received via an analog input
on any connected interface. To specify the analog
input for time code, use the MOTU SMPTE
Console application. For details, see “SMPTE
Source” on page 104.
2408mk3: Video
Choose this setting to resolve the PCI-424 card
(and all connected interfaces) directly to video
being received via the Video In BNC connector on
a 2408mk3 interface. (Only the 2408mk3 interface
supports this feature.) In this sync mode, the
system can also reference SMPTE time code via
any analog input. To specify the input for time
code, use the MOTU SMPTE Console application.
For details, see “SMPTE Source” on page 104.
2408mk3: Word Clock In
24I/O: Word Clock In
HD192: Word Clock In
These settings refer to the Word Clock In BNC
connector on their respective interface. Choosing
one of these settings allows the entire PCI-424
system (including other 2408mk3 I/Os connect to
the PCI-424 card) to slave to an external word
clock source, such as the word clock output from a
digital mixer.