Alesis ADAT HD24XR
A big, heavy, "very '90s" hard-disk workhorse that did one thing - 24-track capture - and did it without asking you to reboot.
Overview
The ADAT HD24XR is the high-resolution member of Alesis's HD24 hard-disk recorder family. The pitch was simple: 24/96 recording without the hard part. Alesis's own advertising framed the unit around reliability and connection count rather than software features. The copy leads with the line that it's hard to perform your best when you spend half your time rebooting. Then it promises the HD24XR is ready to go with all the connections you'll need, so you can forget expensive cards and cables. That's marketing, not a measurement, but it shows who Alesis thought was buying: engineers who wanted a tape-replacement box, not a DAW in a rack.
The numbers first. At the base rate the recorder handles 24 channels of simultaneous 24-bit/48kHz recording. Push it to 96kHz and that halves to 12 channels of simultaneous 24-bit/96kHz. Every high-res recorder of the period made that tradeoff, so know it before buying. Alesis's literature for the line also quotes greater than 110dB dynamic range with less than 0.002% THD+N. Pro-Audio-Review (October 2003, p.92) reproduced those same dynamic-range and distortion specifications alongside the channel counts in its coverage of the unit, so they aren't just ad copy.
Connectivity was the design priority. The HD24XR ships with 24 channels of TRS analog and ADAT Optical digital I/O included - no option cards to buy - plus built-in MIDI, Ethernet, ADAT Sync, and Word Clock connections. For anyone who already owned an ADAT rig, that optical bank meant the new hard-disk box could slot into an existing setup rather than replace it. The dual hot-swappable bays take low-cost IDE hard drive media. That is both the machine's great practical virtue and, decades later, its biggest headache. More on that below.
One distinctive engineering claim is Alesis's FST file technology, which the company said eliminated the need to defragment a hard drive. The rest of the feature set is the unglamorous stuff that keeps a session moving: basic editing functions, MTC, and a remote control surface. Pro-Audio-Review (November 2003, p.52) listed the unit in its multitrack buyer's guide with a price of $2,999, describing it as a 24-track, 24-bit hard-disk machine covering 44.1kHz, 48kHz, and 96kHz sample rates.
Owners and reviewers were clear that the HD24XR was not portable or modern. A Pro-Audio-Review writer looking back in September 2014 (p.38) described having used the HD24XR for all non-DAW tracking needs for nearly a decade. He called it a big, heavy yet serviceable machine dependent on removable 80GB IDE drives, and pointedly "very '90s" in character. The same writer was happy to slip a thumb drive into a jeans pocket instead.
The HD24XR is a purpose-built capture device with a fixed place in a workflow that has largely moved on. Its dependence on aging IDE media is the main practical concern for anyone buying one now. The hot-swappable bays are convenient right up until the drives themselves become the scarce, failure-prone part of the system. Expect to source and test media carefully, and treat any included drives as a bonus rather than a guarantee. The analog and ADAT I/O, the Word Clock and ADAT Sync connections, and the 24/96 conversion are all still useful for anyone integrating one into a hybrid setup.
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