Alesis Adat HD-24 Recorder

I have four (4) Alesis Adat HD-24 recorders that I purchased and did not know it until I discovered them in a closet still in the boxes shortly after purchasing a recording studio in Apex, NC a few years ago.

The Alesis ADAT HD-24 is undoubtedly one of the most influential and successful recording products of all time. The Alesis tape-based Adat HD recorder records onto inexpensive IDE hard drives. This 24-track recorder uses the Adat’s 9-pin sync interface to lock multiple machines with a single-sample accuracy and to synchronize their transports. You can sync up to four (4) machines for a total of 96 channels and you can carry them in the trunk of your car and another interesting feature about the Alesis Adats HD-24 is the ability to slip tracks backward or forward at a speed of 17 ms.

The Alesis comes with an optonial Little Remote Control (LRC), which includes transport control and the essential recording and location functions. You can also control the recorder remotely using MIDI Machine Control (MMC). The MIDI I/O is also used for MIDI Time Code (MTC) output and for updating the firmware.

The Alesis Adat HD-24's analog converters operate at sample rates of 44.1 Khz or 48 kHz, and come with an optional 96 Khz I/O board. You can run the stock unit as a 12-track, 88.2 or 96 Khz recorder using the Lightpipe I/O and external A/D and D/A converters. You can copy and move the audio data in a digital audio computer system (DAW) and transfer it back into the Alesis ADAT HD-24 via FTP, using the recorder's built-in 10Base-T Ethernet port. However this method of transferring music files to a computer can be very slow, especially if you are transfering 96 channels. But, in January 1999, Alesis introduced an incredibly affordable priced software package called ADAT/PCR. It is the only ADAT-compatible interface card with both ADAT Optical and ADAT Sync inputs and outputs in a single PCI card. The transfer utility in ADAT/EDIT automatically identifies ADAT recorders in the system and works in tandem with the ADAT Sync interface to maintain precise synchronization between the Alesis and the computer. This I have found to be very useful and easy if you want to transfer 24 - 96 recorded channels of music directly into Pro Tools for Mastering and Editing. The transfer takes only a couple of minutes.

The Alesis Adat HD24's IDE hard drives are mounted in removable caddies that slide into its two bays. In our four (4) Alesis Adat HD24 recorders we have 360 GB hard drives that have work flawlessly for the past 4 years, but the new Alesis running 2.0 Bias will handle a maximum drive size of 2-terabytes (TB) which is 2,000 GB.

Another feature I really like about the hard drive caddies, if you do remove a hard drive to temporarily send out to another recording studio, it takes approximately 5 seconds to remove, and if you replace a hard drive it taks approximately 90 seconds to take it out and replace it with a new hard drive – very easy. You can use any 4-inch IDE (or compatible variants, such as the Ultra ATA/100) drive with a spindle speed of 5,400 rpm or greater, and both drives are hot swappable.

One draw back,  if you purchase a used older version of Alesis running 1.0 Bias, it will not work with Western Digital hard drives. The Western Digital hard drives will not format with the patent Alesis FST hard drive format, so it is best to get the Alesis Adat HD24 with 2.0 bias.

At the time the Alesis ADAT HD24 was being developed, the inexpensive IDE hard drives that were available were not always up to handling 24 tracks of 24-bit, 48 kHz audio. So Alesis came up with a patent-pending Alesis FST hard-drive format to improve disk performance.

FST writes data sequentially rather than at random points across the drives, cutting seek time to almost nothing and eliminating the need for disk defragmentation. This reduces wear and tear on the hard drives.. But on the other hand this proprietary format can not be read by standard computers.

Alesis Adat HD-24 Recorder