The ADAT Lightpipe format was originally developed to provide a multichannel interface for the Alesis brand “Alesis Digital Audio Tape” machines. Although the original model was limited to 16 bit wordlength, the ADAT Lightpipe transmitted and received 24 bit words. The format is specified to support eight channels of 24 bit digital audio at a Sample frequency (SF) of either 44.1 or 48 kHz. In order to support higher SF’s, SMUX was developed which allowed the transmission of higher sample frequencies by trading-off channel count for higher SF. SMUX allows four channels of 24 bit digital audio at a SF of either 88.2 or 96 kHz on one fiber optic interconnect. Higher sample frequencies can be supported as well, and other manufacturers which adopted the ADAT format offer transmission of two channels of 24 bit digital audio at a SF of either 176.4 or 192 kHz.
- Although the ADAT format uses the same physical connection as optical S-PDIF (Toslink), the two formats are not compatible.
There are a number of formats which can use the Toslink format physical connection including SPDIF (2 channel), ADAT (8 channel), and audio for video formats such as Dolby Digital and DTS (Surround). None of these formats is compatible with any other.
- When using a digital audio interface that supports ADAT as well as S-PDIF with Lavry converters, the S-PDIF format must be selected for proper operation.