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Originally an 8-track digital recorder, now shorthand for a digital transmission protocol

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ADAT (Alesis Digital Audio Tape)

An eight track digital recorder developed and manufactured by the Alesis Corporation, employing modified videotape recording technology. The ADAT uses a standard VHS video cassette for information storage.

Alesis Digital Audio Tape or ADAT, first introduced in 1991, was used for simultaneously recording eight tracks of digital audio at once, onto Super VHS magnetic tape - a tape format similar to that used by consumer VCRs. Greater numbers of audio tracks could be recorded by synchronizing several ADAT machines together. While this had been available in earlier machines, ADAT machines were the first to do so with sample-accurate timing - which in effect allowed a studio owner to purchase a 24-track tape machine eight tracks at a time. This capability and its comparatively low cost were largely responsible for the rise of project studios in the 1990s.

Several versions of the ADAT machine were produced. The original ADAT (also known as "Blackface") and the ADAT XT recorded 16 bits per sample (ADAT Type I). A later generation of machines - the XT-20, LX-20 and M-20 - supports 20 bits per sample (ADAT Type II). All ADAT's use the same high quality S-VHS tape media. Tapes formatted in the older Type I style can be read and written in the more modern machines, but not the other way around. Later generations record at two sample rates, 44.1 kHz and 48 kHz, although the original Blackface could only do 48 kHz. Most models allow pitch control by varying the sample rate slightly (and tape speed at the same time).

With locate points it was possible to store sample exact positions on tape, making it easy to find specific parts of recordings. Using Auto Play and Auto Record functions made it possible to drop in recording at exact points, providing the first automated punch-in / punch-out system (citation needed).

Although it is a tape based format, the term ADAT now refers to its successor, the Alesis ADAT HD24. This is the next step in stand alone digital multitrack audio recorders, and features hard disk recording as opposed to the traditional tape based ADAT, which is now considered obsolete—although computer based recording makes devices such as the HD24 arguably equally obselete, many engineers still use the HD24 system for redundant backup or fallback, with the newer HD24XR which features much better converters, a possible 96kHz sample rate, and is preferred to computer recording by some.

ADAT Lightpipe Protocol
"ADAT" is also used as an abbreviation for the ADAT Lightpipe protocol, which transfers 8 tracks in a single fiber optic cable. The ADAT cable standard is no longer strictly tied to ADAT tape machines, and is now utilized by analog-to-digital converters, input cards for digital audio workstations, effects machines, etc. One of the original benefits of utilizing ADAT versus S/PDIF or AES/EBU was that a single cable could carry up to eight channels of audio. (AES10 (MADI) can now carry up to 64 channels.)

Many audio interfaces will feature ADAT in/out ports as a low-footprint option for expandability and connectivity.


anonymous Mon, 01/02/2023 - 13:29
Wow. Where do you get your information? And how scary it is you put forth your blog as factual. ADAT does NOT use standard VHS tape stock which is lower bias, iron-oxide, with an incompatible shell (look at the registration hole pattern on the bottom of the shell). It only uses high-bias, ferric metal, S-VHS tape, with a different format registration pattern (holes) on the beefier shell. Now, here's what budles you with every lame wedding videograoher from the 1990s: The "S" in S-VHS does NOT stand for SUPER!!! it stands for "Separate" as the Y (luminance) and C (chrominance) was recorded separately in ANALOG form, requiring the ferric, high-bias tape. I won't waste my time addressing your tangle of hardware version releases. Next time, though, consdier adding phrases like, "I think, maybe, not sure, and I never owned one professionally." Signed, Original 1991 ADAT Worldwide Studio Network Member

paulears Thu, 02/16/2023 - 05:58
Just noticed this - it's a reply to a really ancient topic, but could I just comment? He said: "The ADAT uses a standard VHS video cassette for information storage." A little further he mentioned the formulation was Super VHS type tape. The ADAT branded tapes we bought in hundreds from people like HHB in the UK were indistinguishable from the usual S-VHS tapes, and used the same ID hole. Our machines, the Mk1 and Mk2 versions were happy on S-VHS tape. By the way - S did stand for Super, and This was printed on loads of tapes back then, you must have forgotten. If you google for Fuji S-VHS, you will see the word 'Super' pretty prominently. Alesis told people to use 120 maximum length S-VHS tapes. They did originally tell people they didn't recommend ordinary VHS tapes, but they were careful to say 'could' cause problems with oxide shedding and dirty the heads. They did however tell people not to use budget tape. That's an important distinction. As far as I know, the only shell difference is the single hole. You will also discover many S-VHS recorders had the word SUPER in very bug letters. Sure, S-VHS was component, with separate Y/C but that is not a marketing feature, the word super was. I doubt the original poster will read your post, but when you tell people off, perhaps you might make sure your facts are also accurate. I'm old enough to have been working with S-VHS when it first appeared and I can tell you that everyone from the manufactures at that time used the word Super, and NONE used the word separate - even though that is a better description. Super VHS was a very standard term, and separate VHS was simply not. I think I went to JVC, Ferguson, Panasonic, Hitachi launch events and it was always Super - indeed, when Sony brought out their Super Beta - they too called it super. Perhaps When the Betacam SP range came out, the SP indicated superior performance, again, no separate. So - no need to chastise that poor fella for a post basically correct in almost every way.