Alesis ADAT (1991–1999)
Digital 8-track recorder using S-VHS tape, capable of sample-accurate synchronization across up to 16 units for 128-track recording.
Overview
The Alesis Digital Audio Tape (ADAT), first announced at the January 1991 NAMM Show and shipped in early 1992, was a digital 8-track recorder that used standard S-VHS tapes to record digital audio. Marketed between 1991 and 1999, it became a cornerstone of affordable digital recording, enabling project studios to record albums independently. The original model, later known as "Blackface," was followed by the ADAT XT (introduced in 1996), the XT20 (1998), and other variants like the M20 and LX20. Up to 16 ADATs could be synchronized via nine-pin sync and optical connections for up to 128 tracks with sample-accurate timing.
Specifications
| Media Type | Magnetic cassette tape (S-VHS) |
|---|---|
| Track Count | 8-track |
| Bit Depth | 16-bit (Type I), 20-bit (Type II on XT20, M20) |
| Sample Rates | 44.1/48 kHz (switchable) |
| Form Factor | Rackmountable |
| Audio Connections | EDAC (+4dBu), phono (-10dBV), ADAT optical interface |
| Control Connections | Punch In/Out and Locate/Play footswitch jacks, LRC/BRC remote support |
| Dynamic Range | 92dB (Type I), 102dB A-weighted (Type II) |
| Frequency Response | 20Hz–20kHz, flat within ±0.5dB |
| Autolocate Points | 10 on-board, accurate to 10ms |
Design
The ADAT XT and XT20 share the same modified Panasonic S-VHS transport mechanism, capable of winding up to four times faster than the original ADAT. The tape remains engaged during operation unless idle for several minutes, reducing head wear. Inside, new ASICs replaced LSI chips, and control software introduced dynamic braking that continuously adapts to transport performance. A protective air cushion forms between tape and head during fast-wind. The original ADAT inverted input phase during conversion; the XT eliminated this inversion. The chassis is rigid cast aluminium, weighing seven pounds, with anodised pale champagne finish on XT/XT20 models.
Context
Priced at $3,995 at launch (later $2,995), the ADAT offered a fraction of the cost of competing digital reel-to-reel systems from Sony or Mitsubishi. It became a bridge between analog tape and hard disk recording, symbolizing the rise of home and semi-professional studios, especially when paired with Mackie mixers. Alesis produced over 140,000 units during the format’s lifespan, with peak sales reaching 3,000 units per month. In 2004, it was inducted into the TEC Awards TECnology Hall of Fame for revolutionizing affordable recording.
Market
Common issues include Error 9, often caused by a worn idler wheel (rated for 300–750 hours) or dried lubrication on the tachometer shaft. Belts and foam in the lid may degrade over time. Replacement parts are scarce and expensive, though repair workarounds exist, such as using O-rings for idler wheels. One owner reported purchasing three ADAT XT units for $110 total.
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