ADAT II-20
The archive cannot pin this name to a single machine. The paper trail is worth documenting anyway.
Overview
The ADAT II-20 does not resolve to one product. The fact sheet for this entry came back empty - no verified identity, no production years, no price, no specifications. The only source material attached to the model is a batch of period documents that name several different Alesis machines and never settle on "II-20" as a designation. What the archive can say with confidence is narrower than a spec dump. The "II" and the "20" in the name both point at a real thing in the ADAT lineage, and the surrounding documents show what that thing was.
"Type II" is the recording format that writes 20 bits to tape, and it runs through all the period material. A period Alesis advertisement reproduced in the trade press describes the M20 as implementing ADAT Type II. It calls it the only MDM format that writes 20 bits to tape with no compression and no noise shaping, and it credits the 24-bit A/D converters with 117dB of dynamic range. The same copy claims sixteen times the detail of the 16-bit format. That is manufacturer language, not an independent measurement, so read it that way. It does establish the vocabulary. "Type II" plus "20-bit" is a real Alesis position, and a buyer who runs into the string "II-20" is almost certainly looking at a machine from that family rather than a phantom model.
The XT20 is the other anchor. A period Alesis ad reproduced in the trade press lists the XT20 with ADAT Type II format recording 16- or 20-bit digital audio, on-board digital editing with 10-point autolocating, a faster transport under intelligent software control, and a solid aluminum die-cast chassis. The same listing quotes 102dB dynamic range at a 48kHz sample rate, up to 16 XT20s linked for 128 tracks, recording on standard S-VHS videocassettes, and both +4dBu balanced and -10dBu unbalanced connections. Mix (1998, p.120) covered the XT20's debut at that year's NAMM show. None of that is attributable to a product called the II-20. It belongs to the XT20. But the XT20 is the closest documented machine to the name.
The LX20 sits alongside it in the same period advertising, and the difference matters on the used market. The LX20 is listed with five specialized locate points against the XT20's ten. Its record-side converter is described as a 20-bit linear codec at 64-times oversampling, single converter per channel. Sound on Sound (August 1998, p.34) reviewed the LX20 as the junior member of the Type II family at £1699, praising its attractive price and ease of use. The two machines share the 20-bit format but differ in how they work. A listing that says only "20-bit ADAT" doesn't tell you which one you are buying.
The archive will not invent a II-20 around a designation that no document in hand confirms. The fact sheet is explicit that no research was supplied and that the exact product name could not be verified. It flags the string as an unusual combination and points toward the XT20, LX20, or M20 as the likely intended model. The Type II 20-bit ADAT era is well documented. A machine sold under the exact name "II-20" is not, in these sources. Treat any listing that quotes specifications for a "II-20" as unverified until a manual, a period review, or a factory spec sheet naming that exact model turns up.
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