User`s guide

Chapter 3: Using Your System 37
Choosing the Transport Master
In a synchronized setup, you must decide
which system, Pro Tools or ADAT, will pro-
vide the positional reference for both sys-
tems and function as the transport master.
This is necessary for both systems to start
and stop playback/recording from the
same time code/session location.
Because Pro Tools can both broadcast and
respond to MIDI Machine Control (MMC),
you can use MMC to communicate trans-
port commands (such as Play, Stop) be-
tween your devices. When playback be-
gins, time code (usually MIDI Time Code,
or SMPTE in some setups) provides the po-
sitional reference to keep all the devices at
the same place while the designated clock
master (Pro Tools, ADAT, or Slave Clock-ca-
pable synchronization peripheral) keeps
everything running at precisely the same
speed/sample rate. Your choice of transport
master will depend upon what type of syn-
chronization device you are using, and in-
structions for selecting the transport mas-
ter are included in each of the following
setup examples.
✽ If you use Pro Tools MIDI Machine Control,
you can use the Pro Tools Transport Master
popup menu (in the Transport window) to con-
trol either Pro Tools or the ADAT. Refer to your
Pro Tools manuals for more information.
ADAT as Master Clock and Pro Tools as Slave
In general, you should make ADAT the
master clock device when you are transfer-
ring audio originally recorded on ADAT to
Pro Tools. Also, because Pro Tools is a non-
linear system, it is ideally suited to be a
slave device (it can cue up instantly with-
out having to wind tape). In some situa-
tions, however, Pro Tools must be the clock
master. These situations are noted as in the
setup examples that follow.
Pro Tools as Master Clock and ADAT as Slave
In general, Pro Tools should be the master
clock device when you are transferring au-
dio originally recorded in Pro Tools to an
ADAT, or whenever the ADAT Bridge I/O is
not your primary audio interface.
Both Pro Tools and ADAT as Slaves
If you are using an external synchroniza-
tion device such as a Digidesign Universal
Slave Driver (or any Slave Clock-capable
device such as the MTP AV or 64XTC) that
device should provide the master clock sig-
nal to which both Pro Tools and the ADAT
will be slaved.
The sections that follow provide instruc-
tions for achieving synchronized play-
back/recording between Pro Tools and the
ADAT using a number of different devices.
Please refer to the section that applies to
your particular setup.
✽ The sync circuitry built into your ADAT Bridge
is able to automatically detect whenever an ex-
ternal sync source is lost. In such a situation,
the ADAT Bridge I/O will automatically switch
to internal sync mode until the external sync
input is reconnected to ensure that playback is
maintained even if the sync source is re-
moved.