About Digital Audio I N /Out; Adat Optical Interface Basics; About 16-Bit And 20-Bit Signal Transfers - Alesis ADAT-LX20 Reference Manual

A
BOUT
The ADAT Optical Interface carries 8 tracks of digital audio between ADAT
compatible products such as:
Multiple LX20s and ADAT
QuadraVerb 2
Q20
Many Alesis keyboards
ADAT-PCR computer interface card
3rd-party products (Digidesign ADAT Bridge, Yamaha 02R digital mixer, etc.)
Digital bussing requires one fiber optical cable (included) for each LX20 or other
ADAT-compatible product. Additional cables are available from your dealer in
various lengths up to 16 feet (about 5 meters). This connection can be made while
power is on or off.
ADAT O
The Optical Interface sends (or receives) up to 8 simultaneous channels of digital
I/O over a single fiber optic cable. Compared to wire cables, fiber optics contributes
no noise or interference, the optical isolation prevents ground loops, and if you need
to know if something's sending a signal, just look at the cable's output connector to
check for a glowing red light.
As cable capacitance is not an issue, waveforms retain all their high frequencies as
they pass through the cable, thus maintaining the integrity of the waveform
shape. However, fiber optic cables are somewhat fragile, so route them out of
harm's way.
A 16-
BOUT BIT AND
The ADAT Optical Interface is designed for the future, and can transfer digital
data with up to 24-bit resolution. Current Alesis products use 20-bit resolution, a
quantum improvement over earlier 16-bit designs.
At the receiving end, ADAT Type I machines (the original ADAT "classic" and XT)
convert any incoming signal to 16 bits. Type II machines (e.g., the M20, LX20, XT20,
and PCR card with proper software) can accept 16 or 20-bit signals, and convert 24-
bit signals to 20 bits.
Note: Type II machines will convert 16-bit signals to 20 bits, however the last 4 bits
will be zeroes, and not increase the actual resolution beyond 16 bits.
ADAT LX20 Reference Manual
C
HAPTER
D
IGITAL
I /O
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I
PTICAL NTERFACE
20-
BIT SIGNAL TRANSFERS
Chapter 8 - About Digital Audio In/Out
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UDIO
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