48 Khz Clock Out; Powering-Up - Alesis AI-1 Reference Manual

4. Connect the other end of the fiber optic cable to the S/PDIF optic
input, OR, connect the other end of the RCA cable to the RCA
input of the AI-1.
Note: Both the optic and RCA outputs are active when the AI-1's
Destination is set to S/PDIF. This means you can route digital
audio to two S/PDIF devices simultaneously. When the AI-1's
Source is set to S/PDIF, the RCA input has priority over the
optic input. If the AI-1 does not detect a device connected to the
RCA input (no sample clock present), it will automatically
switch over and use the optic input. Since the switch is
determined by the presence of a sample clock, you could leave a
device connected to the RCA input, and simply turn its power
off when you wish to use the optic input.

2.3 48 KHZ CLOCK OUT

The 48kHz output signal is a 75 TTL level square wave output,
and is provided via a BNC-type connector. If you are using the BRC
Master Remote Control and plan to record onto ADAT from an
AES/EBU or S/PDIF source, the 48kHz clock out must be connected
to the BRC so that it can be synchronized with the source's clock
rate.

2.4 POWERING-UP

Normally, the AI-1 does not need to be powered up in any order for
it to work with one or more ADATs. The system can even be
connected while the power is on.
When using the BRC as the system's master, however, the order in
which the devices are powered-up is important. After all
connections have been made, turn on the power of each ADAT in
the system, turn on the AI-1, and then turn on the BRC.
For more information on using the BRC, please refer to the BRC
Reference Manual.
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