Alesis ADAT HD24 (2002–2003)
Twenty-four tracks of 24-bit/48k on a hot-swappable IDE caddy, priced at $2,499 - the tape-based ADAT's last, best argument for itself.
Overview
The number to look at is 24. Twenty-four channels of simultaneous 24-bit/48 kHz recording, on a machine that lists at $2,495 and comes with everything you need to make a record. No cards, no cables, no expansion chassis. Alesis built its reputation on the modular digital multitrack tape deck, and the ADAT HD24 is the company's move to random access: a hard-disk recorder dressed in a tape machine's clothes. The front panel keeps the transport buttons where a generation of ADAT users instinctively reach for them, and the operating logic follows the same path. Mix (July 2002, p.102) put it plainly - the HD24 arrived nearly two years after the first modular 24-track hard-disk recorders, following Tascam and Mackie into the category but carrying over the tape-style transport interface that made ADAT familiar.
The box contents are unusual for the era. Twenty-four channels of balanced ¼-inch TRS analog I/O and twenty-four channels of ADAT Lightpipe digital I/O are standard, not options. A built-in 10Base-T Ethernet port turns the machine into an FTP server so files can be pulled to a DAW. MIDI In and Out, ADAT Sync, and Word Clock are all on board. Two removable IDE drive caddies slide into the front. One ships with a 20 GB drive, the other empty. Alesis's own advertising in EQ (March 2002, p.69) billed the removable IDE media as "cheaper than ADAT tape per track minute." The tape was the expensive part, and now there wasn't any.
The converters surprise people who expect a $2,499 box to sound like a $2,499 box. There are twenty-four pairs of them. Electronic Musician's reviewer recorded instruments through Millennia Media STT-1 channel strips and compared against converters at several price points. His conclusion was that what came back was pretty much what went in, with no reason to be afraid to use them. They are not the equal of converters costing several times as much, particularly on highly dynamic material, but he found them confounding at the price. Alesis quotes greater than 110 dB dynamic range and less than 0.002% THD+N.
High-resolution work needs a careful read of the spec sheet. The stock analog converters run at 44.1 or 48 kHz. To record at 88.2 or 96 kHz you use the Lightpipe I/O and external A/D and D/A converters, and the track count drops to 12. The machine splits samples across two channels to get there. Each channel plays back normally on 44.1/48k gear, but unless the receiving device can reunite the split track, you can't use processing that alters the data. That rules out crossfades, EQ, and in some cases gain changes. Copy the audio into a DAW and transfer it back over FTP and the track is reunited automatically. The optional EC-2 96 kHz analog I/O board was announced at $1,249. A FirePort ($249) let you mount the caddied drives on a computer's FireWire port.
Drive handling is the HD24's quiet strong point. Caddies load in roughly 90 seconds, drives are hot-swappable mid-session, and any 4-inch IDE or compatible variant, Ultra ATA/100 included, with a spindle speed of 5,400 rpm or greater will work. The maximum drive size is a reported 2 TB, which is 2,000 GB of storage in a machine from 2002. Alesis developed a patent-pending FST drive format because the inexpensive IDE drives of the development period weren't reliably up to 24 tracks of 24-bit/48 kHz audio. The company's later advertising claimed FST meant you'd never need to defragment a drive. The stock 20 GB disk reportedly performed reliably through weeks of testing.
Operation is where the tape heritage pays off. Anyone who has run an ADAT can walk up and use this machine. Electronic Musician found the manual clear and complete, the buttons grouped logically by function (file/name, editing, location, digital sync, digital I/O), and navigation handled by a four-arrow cluster with a display that guides you even when you've done something nonsensical like hitting play before loading a song. The machine stores 64 songs per drive. Scrubbing audio for editing is a two-button hold on the machine itself, Stop plus Rewind or Fast-Forward, and not something the LRC remote does. Twenty autolocation markers are available, seven with dedicated buttons, some assigned to loop, punch, and edit in/out points.
The limitations are plain. There are no virtual tracks, so no alternate takes or playlists per physical track, the feature users of DAWs take for granted. Standard auto punch-in/out and rehearsal are there, footswitch-controllable for hands-free work. There are no input controls at all. Levels are set at the source and monitored on dedicated ten-stage peak-reading meters calibrated at −15 dBFS. And 10Base-T Ethernet, while useful for moving files, is slow. The reviewer's verdict was that real-time Lightpipe transfer is usually faster, especially with lots of tracks, because the HD24 sends whole-song-length tracks rather than selected regions. A desire for 100Base-T or gigabit appeared in print and never materialized in this model.
Sync is solid. Standard ADAT 9-pin sync is supported, and the MIDI Out sends MTC directly to a sequencer, so a computer and the HD24 can lock without an external synchronizer, though not sample-accurately that way. It receives MMC but not MTC through MIDI In. In Digital Performer the HD24 simply appears as three ADATs in the Machine Control window, letting you record-enable all 24 tracks. Logic Audio integration was likewise reported as straightforward. Editing gives cut-and-paste with 99 levels of undo. The lighted transport buttons aside, the buttons are the rubbery plastic type found across Alesis products of the period, which owners report stand up well to repeated stress.
Age matters on this machine. The 2002-2003 window means the drives are the wear item: 5,400 rpm IDE disks of that vintage are old, and the caddies and their connectors are the parts that fail. The FirePort path to a modern computer is the practical way to rescue archived projects. Prices on the used market sit well below the original $2,499, which makes a working HD24 one of the cheaper routes to 24 channels of clean 24-bit conversion with a real tape-style transport. Electronic Musician's review closed by saying the HD24 carries forward what made tape-based ADATs appealing - simplicity, clean sound, and value - into a workhorse hard-disk recorder, ready for prime time out of the box.
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