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Alesis ADAT (Original)

In 1992 Alesis revolutionized the small and home recording studio world with their ADAT machines. These machines store 8 channels of 48khz digital audio on S-VHS tapes. The tapes have to be formatted, and run faster than a normal VCR runs them.

The machines feature a toslink style fiber optic input and output called lightpipe (carrying 8 channels of audio, not 2), 1/4“ input and output and a large multipin connector for balanced audio in/out snake connection. The machines have the ability to sync multiple units to scale out a studio to 16, 24, 32 tracks and so on. There is a big remote control (called BRC) that has larger timecode readout and other features that was optional. In addition, a little remote control was available that featured the basic controls and connects via a 1/4” connection to one of the machines.

The machines are known to be somewhat unreliable, but from my (Ethan) experience tapes recorded on quality professional / broadcast media that was stored at least halfway okay seems to often play back error free today (late 2018.)

The units were superceeded by later ADAT models that offered higher sample bit depth and vacuum florescent displays.

The final product in the ADAT line was the HD24 series, a 24 track unit that carried the ADAT name but uses PATA IDE hard drives for storage.

Laser show use

While these machines were meant for recording audio, be it from the studio or from an alien planet in the movie “Contact,” they provided the needed capabilities for laserists to record laser show material. Usually channels 1 and 2 carry the X and Y signal, 3 4 and 5 are RGB color channel, 6 is SMPTE or other misc data. 7 and 8 are finally used for the stereo audio. Bigger shows would use a second machine “chasing” the first with additional projector channels.

Lightpipe IO

The lightpipe interface allows data to be exchanged unit to unit with no loss (assuming tape reads well.) There is a number of older computer audio interfaces that feature these lightpipe interfaces. Many of them rely on PCI cards which do not fit the current generation of computers. There is one 8 channel lightpipe I/O interface called miniDSP that can be used with audacity and other Windows ASIO software, as well as Mac (and with a lot of work – Linux.) The SGI Octane series of computers also featured Lightpipe I/O but only supports 8 channel I/O recording in the last version of IRIX.

Hooking laser projector to Black ADAT

Pangolin kindly published details on how to remove the capacitors from the output stage of the black ADAT units to directly pass the laser show signals to a projector:

The later ADAT machines (which have their own page here) featured surface mount components and instead of hand modification there is a board that was produced by Pangolin called the CADA-MOD that corrected the outputs for direct DC output for laser show use.

There is also a convenient set of interfaces from Aldebaran Systems that provide ILDA to Lightpipe and Lightpipe to ILDA. This is the easiest way to connect ADAT hardware to laser projectors, and works well with the HD24 hard drive recorders. More information is available here:

Companies that shipped productions on ADAT

Shows were sold on ADAT format from content producers to planetariums, museums and the like. Most companies in the early 90s most likely used this format.

Modern times

black_adat.txt · Last modified: 2018/09/16 13:02 by telmnstr