Alesis ADAT HD24 (2002)
24-track hard disk recorder with 24-bit resolution, designed to replace tape-based ADAT systems.
Overview
The Alesis ADAT HD24, introduced in 2002, is a 24-track hard disk recorder built to integrate seamlessly into existing ADAT setups. It operates like a tape-based analog recorder, offering sample-accurate editing with 99 levels of undo for cut, copy, and paste operations. The unit records and plays back 24 tracks simultaneously at 24-bit/48kHz, with up to 12 tracks available at 88.2/96kHz when equipped with the optional EC2 upgrade board. It uses Alesis’s proprietary ADAT File Streaming Technology (FST) to minimize disk fragmentation and supports standard IDE hard drives up to 137GB in removable 3.5-inch caddies. One 40GB drive is included, providing 40 hours of 24-track recording at 24-bit/48kHz.
Specifications
| Original Price | $2,499 |
| Audio Resolution | 24-bit |
| Tracks | 24 tracks simultaneous recording and playback |
| Sample Rates | 44.1kHz, 48kHz (88.2/96kHz with EC2 upgrade) |
| Inputs/Outputs | 24 TRS balanced I/O (1/4", +4dBu) |
| Digital I/O | 3 ADAT Optical in, 3 ADAT Optical out |
| Sync I/O | Word Clock (BNC), ADAT 9-pin, Footswitch, LRC remote |
| Networking | 10Base-T Ethernet (RJ-45) for file transfer |
| Drive Type | IDE (ATA/EIDE), 3.5-inch in removable caddies |
| Included Drive | One 40GB hard drive |
| Max Drive Capacity | 137GB per caddy |
| Rack Space | 3U (19" wide, 17" deep, 5.09" high) |
| Weight | 24 lbs |
| Power | 90–230V AC, 60W |
| Dynamic Range | 103dB A/D, >103dB D/A (A-weighted) |
| Frequency Response | 20Hz–20kHz +0/–1dB |
Design
The ADAT HD24 features a rugged steel chassis built for professional studio durability and uses standard user-replaceable IDE hard drives formatted in FAT32. It includes a built-in fan, which is audible but typically does not interfere with critical listening at a distance. The front panel has rubberized buttons, a backlit LCD display, and a shuttle/jog wheel for transport control. The unit records using Alesis’s proprietary ADAT File Streaming Technology (FST), which writes tracks to adjacent disk sectors to reduce fragmentation and seek time. It lacks a graphic waveform display or external monitor support, and editing is performed without virtual tracks. Punching in overwrites material irreversibly, though a "rehearse" mode allows punch practice. The EC2 upgrade replaces the converters with AKM models and enables 88.2/96kHz operation.
Context
Marketed as "the world's first 24-track hard disk recorder designed to fit into any ADAT environment," the HD24 was positioned as a direct replacement for tape-based ADAT recorders. It followed earlier hard disk recorders from TASCAM and Mackie and competed with models like the TASCAM MX-2424 and Mackie HDR24/96. Designed exclusively for music recording, it offered a cost-effective upgrade path for analog users, with the lowest media cost per track minute known to reviewers at the time. It can be sample-accurately synchronized with other ADATs and controlled via an ADAT BRC.
Market
The ADAT HD24 was praised for its reliability, with one reviewer logging 30 hours of use without glitches and calling it "the best way to archive multitrack audio." It is regarded as flexible, reliable, and cost-effective, with owners reporting long-term use and successful integration with modern digital mixers. The 10Base-T Ethernet port is slow—transferring a 750 MB file takes about 18 minutes—and backups are limited to full drives or individual songs, making incremental backup cumbersome. Naming songs via front-panel controls is considered cumbersome, and the unit lacks simultaneous mirroring to both drive bays. A service manual exists, though it omits the switch-mode power supply schematic.
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