ADAT

The Alesis Digital Audio Tape or ADAT ( eng. Alesis digital audio tape ) was introduced in 1992 by the same company. On the one hand, it refers to the recording system, which allows digitally record audio signals to S- VHS tapes and on the other the audio interface for transmitting audio signals by means of fiber-optic cable ( " ADAT Lightpipe ").

Use

Recording system

In general, the ADAT tape has (or S -VHS tape ) on eight tracks, which can as often be dubbed, and practically losing without sacrificing audio quality, at least until the tape through mechanically quite problematic helical track recording method is worn to such an extent that the implemented error correction is no longer sufficient to reconstruct the original.

ADAT was very prevalent in the 1990s in semi-professional applications, home recording studios, as it this format were starting to perform well on a low budget digital multi-track recording - for connecting several devices also quite with more than eight tracks. With three ADAT devices and two ADAT sync cables between one comes already on 24 tracks and was thus - as far as the track number - already in the area many professional studios. The system should make it possible to connect up to 16 ADAT recorder to a system with a total of 128 tracks absolute phase synchronization.

Fundamental weak point is the operating principle, the use of a tape-based system, and thus in any case linear. The associated disadvantages are mainly mechanical wear and rewind times. In addition, helical scan tapes can not be edited directly, of course - cut - be. For these reasons, the tape -based ADAT recorder systems have been almost completely replaced by non-linear computer - based hard disk recording systems, which can simultaneously record and store a plurality of tracks - at a much lower cost.

ADAT recorders that are currently (2012 ) quite inexpensive acted as used equipment, musicians can still afford good service but even today, if you want to be laid not only on the use of computer software. So ADAT recorders are often used as a parallel instance to guard against computer crashes. The diagnostic systems are digitally connected to the recording system.

The analog quality of the recording unit is superior even with 20 bit systems are still the simple computer sound cards and USB recording systems significantly as quality analog input stages and professional connections are installed. Therefore ADAT is quite a high quality sound and affordable alternative in which the handling is very reminiscent of classic tape recorders and probably any interested person within the shortest possible time should be possible. When buying second hand however, you should make sure that the heads do not have too many hours. The wear is actually here (similar to VHS recorders ) is relatively high.

Audio Interface

The then simultaneously introduced ADAT interface for transferring digital audio signals via fiber optics, however, continues to enjoy great popularity and is in small and medium-sized recording studio standard for multi-channel, digital audio transmission become. The original ADAT format has eight digital audio tracks, using S- VHS tapes. The sampling rate was 48 kHz, the sampling depth of 16 bits with linear quantization. The ADAT interface itself transmits audio data but at a sample depth of 24 bit. For the transfer of the eight data channels ADAT system uses the optical transmission via TOSlink.

Audio data with sample rates higher than 48 kHz can be transmitted to the S / MUX protocol ( Sample Multiplexing): The S / MUX protocol fragmented data streams with higher sampling rates and multiplexes them to multiple ADAT channels. An audio signal with a sampling rate of 96 kHz is divided by S / MUX on two ADAT channels. Thus up to 96 kHz sample rate is reduced with the number of possible channels to 4, and at 192 kHz to 2 used In the current (2013 ) Studio Setups with 192 kHz, this resulted in a stereo channel per optical waveguide. Balancing allows the optical waveguide cascade ( " parallel - switching" ) in order to achieve the original channel number.

One finds ADAT interfaces across manufacturers of audio converters, digital mixers, effects devices and sound cards. With multi-functional recording cards for computers ADAT interface is often combined with the optical S / PDIF interface.