Alesis ADAT
Proprietary Multichannel
Optical Digital Interface
ADDENDUM February 2001
2X Sample Rate (96kHz) Specification
Version 1.0 – February 3, 2001
BACKGROUND
The Alesis ADAT Multichannel Optical Digital interface, designed in 1990, has become an music industry
standard for multichannel digital audio data interchange, primarily because of its ease of use, its low cost
of implementation, its space-saving footprint, and because of the ubiquity of ADAT and ADAT-
compatible products on the market.
The ADAT Optical format was designed to provide easy interconnection of multichannel audio sources
(primarily ADATs, when the specification was developed), and is specified as a nominally 48kHz, 8-
channel, 24-bit data path. Audio data is transmitted and received on separate optical paths; that is, to
both transmit and receive ADAT optical format, a device must use two optical cables.
In recent years, particularly with the advent of the DVD standard, a need has developed in the music
industry to record and transmit audio data at 96kHz sampling rates. Since the ADAT Optical is specified
at a nominal 48kHz sample rate, it was deemed necessary to develop a method for implementation of
96kHz data transfers. This document describes the Alesis approved implementation of a 96kHz, 4-
channel audio interface using existing ADAT optical hardware.
