Recording Digital Audio From Other Sources - Alesis ADAT-XT20 Reference Manual

Multiple ADAT-XT20 Operation: Chapter 5
R D A O S
ECORDING IGITAL UDIO FROM THER OURCES
Recording digital audio onto the XT20 from a source other than an
ADAT-Compatible device requires a digital audio interface, like the
Alesis AI-1 or Otari UFC-24. The AI-1 converts either AES/EBU or
S/PDIF digital audio protocols into the Alesis Multichannel Optical
protocol which the XT20 uses, and vice-versa. Refer to the User's
Manual of the digital interface you are using for more information.
When recording digital audio into the XT20 from another XT20 or
ADAT in a multiple ADAT system, the XT20 recording the audio is
already synchronized with the other machines, so the digital audio is
sample-locked when recorded. This is because all slave machines are
automatically set to External Clock mode (EXT icon lights in the
CLOCK icon group). However, when recording digital audio from some
other source, it is necessary to have the XT20 synchronize to the
incoming digital audio. This can be done differently depending on
whether you are using a single XT20 by itself or a multiple ADAT
system.
If using a single XT20, you must connect the AI-1's ADAT OPTICAL
[OUT] to the XT20's [DIGITAL IN] using a single fiber optic connector.
Press the [DIGITAL INPUT] button on the XT20, and set its Clock
Source to Digital (press [CLOCK SELECT] until the DIG icon lights in
the CLOCK icon group). Now the XT20 will synchronize to the clock
information which accompanies the digital audio coming from the AI-
1, which is originating from the digital audio device connected to the
DIGITAL [IN] of the AI-1.
In a multiple ADAT system, you have two choices: synchronize the
digital audio source to the ADAT system, or sync the ADAT system to
the digital audio source.
If the source does not have any kind of clock input (i.e., it cannot be
synchronized to an external clock), you have little choice but to choose
the later option. This means you must connect the AI-1's ADAT
OPTICAL [OUT] to the [DIGITAL IN] of the master ADAT, which of
course has its [DIGITAL OUT] already connected to the next slave,
and so on. You must then set the master's Clock Source to Digital (press
[CLOCK SELECT] until the DIG icon lights in the CLOCK icon
group). If no digital audio clock is detected (i.e. when no digital audio
is being received by the AI-1), the master XT20's DIG icon will flash
and it will continue using its own internal clock. When digital audio is
sent through the AI-1 (and consequently, a digital clock is received by
the master XT20), the master XT20 will synchronize to the incoming
digital clock (the XT20's DIG clock will stop flashing and remain lit).
If your digital audio source does provide a means for synchronizing to an
external clock, you must connect the last slave ADAT's [SYNC OUT] to
the AI-1's [SYNC IN]. Next, you must connect the AI-1's [WORD
CLOCK OUT] connector to the digital audio source's [WORD CLOCK
IN] connector, and adjust its clock parameter so that it is synchronizing
to the incoming word clock derived from the ADAT system.
ADAT XT20 Reference Manual 97