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 made to fit into existing ADAT setups. It works like a tape-based analog recorder. Editing is sample-accurate, with 99 levels of undo for cut, copy, and paste. It records and plays back 24 tracks at once at 24-bit/48kHz. With the optional EC2 upgrade board, up to 12 tracks run at 88.2/96kHz. It uses Alesis's proprietary ADAT File Streaming Technology (FST) to minimize disk fragmentation, and it takes standard IDE hard drives up to 137GB in removable 3.5-inch caddies. One 40GB drive is included, good for 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 has a steel chassis and uses standard user-replaceable IDE hard drives formatted in FAT32. There's a built-in fan. It's audible, but typically doesn't 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. FST writes tracks to adjacent disk sectors, which reduces fragmentation and seek time. There is no graphic waveform display and no external monitor support, and editing is done without virtual tracks. Punching in overwrites material irreversibly, though a "rehearse" mode lets you practice the punch first. The EC2 upgrade replaces the converters with AKM models and enables 88.2/96kHz operation.
Context
Alesis marketed it as "the world's first 24-track hard disk recorder designed to fit into any ADAT environment," and positioned the HD24 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. It was 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. One reviewer logged 30 hours of use without glitches and called it "the best way to archive multitrack audio." It is regarded as flexible, reliable, and cost-effective, and owners report 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. Backups are limited to full drives or individual songs, so incremental backup is cumbersome. Naming songs from the front panel is also considered cumbersome, and the unit can't mirror to both drive bays at once. A service manual exists, though it omits the switch-mode power supply schematic.
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