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Alesis ADAT HD24 Digital Hard Disk Recorder with EC-2 Upgrade

Since 1984, Alesis has been developing and manufacturing gear for the audio industry. The same company that brought us the ever-so popular eight-track ADAT recorder brought out last year the ADAT HD24, a 24-track digital hard disk recorder. Now available for the recorder is the EC-2 96 kHz Sample Rate Upgrade.

In collaboration with the Conservatory of Recording Arts and Sciences, one the country’s leading pro audio teaching facilities, PAR has introduced a regular series of in-depth reviews conducted at the Conservatory’s state-of-the-art teaching faculty in Phoenix.

Since 1984, Alesis has been developing and manufacturing gear for the audio industry. The same company that brought us the ever-so popular eight-track ADAT recorder brought out last year the ADAT HD24, a 24-track digital hard disk recorder. Now available for the recorder is the EC-2 96 kHz Sample Rate Upgrade. This upgrade allows you to use the analog inputs and outputs at 88.2 kHz or 96 kHz nominal sample rates. Alesis does this for the affordable price of $3,748. Or you can start from scratch with the just released HD24XR, a fully native 96 kHz hard disk recorder for $2,999. The HD24 with the EC-2 upgrade reviewed here is equivalent to the HD24XR.
Product PointsApplications: Studio, remote recording

Key Features: 24-track; 24-bit audio; 1/4-inch TRS inputs and outputs; 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz sampling rates; uses any internal IDE hard drive; ADAT FST recording format; can be used with a BRC or LRC (LRC included) remote controllers

Price: $2,499 with EC-2 upgrade – $3,748

Contact: Alesis at 401-658-5760, Web Site.

The HD24 is a 24-track, 24-bit hard disk recorder that allows the use of affordable IDE hard drives as its removable recording media. It uses a new format engineered by Alesis called ADAT FST, which was specifically designed for music recording.

This format keeps tracks of a given song in adjacent sections of the hard disk, thus speeding up the “seek time” required to search for songs on the drive. This, in turn, provides for much improved drive stability. Because of this, you can use low-cost IDE hard drives, and still have great results. Currently, you can buy hard disk media for around $4 – 5 per gigabyte, which, track for track, is less than that of an ADAT tape. Alesis developed custom drive caddies and storage cases for the HD24, which ships with a 10 GB hard drive (which will give you about 45 minutes of 24-track recording at 24-bit/48 kHz). The other drive slot is empty, for you to install your own drive.

One big advantage of the HD24 above some of the other hard disk recorders is that it comes complete with everything you need to record your session. You do not have to buy any cards or other extra items to get your audio in and out of the recorder. At 44.1 kHz or 48 kHz, you can record 24 tracks; at 88.2 kHz or 96 kHz, you have 12 tracks available. Other connections available include an external BNC word clock inputs, 24 channels of ADAT optical inputs and outputs, ADAT Sync In and Out connectors to allow for multiple machines to be connected (up to five) or to hook up to a BRC. When hooked up to a BRC, the HD24 acts like three ADAT recorders.

The HD24 has three ways to allow the user to move data to and from the recorder:

* Simply by switching drives. You can store the drives on the shelf, just like tape, and bring them back for later use. Drives can be backed up between the two trays in a matter of minutes. With the FireWire-based FirePort peripheral ($249) you can download files directly to a PC.

* ADAT Optical I/O will allow transfer of data to and from the recorder with standard fiber-optic cables.

* Ethernet. Although I was not able to test this function, the HD24 can connect to a computer network as a standalone FTP server with its own IP address accessible from the network or over the Internet.

The HD24 has some synchronization options as well. The machine can generate MIDI Time Code (MTC), send MIDI Machine Control (MMC) messages, and synchronize with ADATs and the M20. The MIDI port is also used for software updates, and to send software from one HD24 to another.

In Use

I was first able to use the HD24 in a mobile recording situation, in conjunction with a small Mackie console. I had not had a chance to read the manual yet, and was able to hook everything up, name my song, set proper levels and clear peaks, and set locate points. (And the important part was: I was able to do it quickly.)

For what we were recording, this was all I needed to know. In fact, I can imagine that for anyone who is using the HD24 in a simple mobile setup, this may be most, if not all, of the functions you would need at the time. We were limited on the number of physical inputs and outputs on the console, and the 1/4-inch jacks on the HD24 made it very easy to switch any of these around any time I needed to. Another thing that I found to be great for saving time was the fact that the drive automatically mounts when you turn on the machine, and unmounts when the machine is shut off. It does this much faster than other hard disk recorders I have worked with. When you power of the machine from the front, it asks you if you are sure you want to switch it off. This is a great safety, and actually prevented me from accidentally turning off the machine at a bad time.

The next time I was able to use the HD24 was on a drum session. Again, I did not read the manual before this session, because I wanted to see what I could do without it. I wanted to compare the lower sample rates to the 96 kHz sample rate. I recorded the same drum tracks at each sampling frequency. Once again, it was very easy to set up in the studio, to set up the number of tracks and sampling frequency I desired, and to name the song. At the 88.2 kHz and 96kHz, you are limited to 12 tracks, which could be inconvenient at times. One thing that fooled me when I first listened back to the session was the fact that at 88.2 kHz and 96 kHz, the outputs for Tracks 1-12 are duplicated on the outputs for Tracks 13-24. I had faders turned up on Channels 13-24 and heard my drums, even though I was seeing no metering on the machine itself. Once I figured out what was going on, I realized that this could be a very handy feature.

I found the 96 kHz session to have much smoother high frequencies. This was especially noticeable on the overhead microphones. It also seemed to me that the kick and snare drums jumped out of the mix more. The low frequencies seemed to be rounder and fuller. The hi-hat and shaker were much less abrasive and the congas were definitely more pleasing to the ear.

Probably the most inconvenient thing is the fact that the BRC cannot be used with the HD24 at the 88.2 kHz and 96 kHz sampling rates, although it can still be used at 44.1 kHz and 48 kHz sessions.

After this session, I read the manual to see some of the other possibilities of the HD24. I found the editing functions to be easily usable, but somewhat basic. You are allowed the functions of cut, copy, paste, and undo. Copying audio from one song to another is possible. Start and end edit times are easy to find with the scrubbing function. Although if I had to do numerous complicated edits on a song, I would probably transfer my audio to a computer editing program like Pro Tools, and then transfer back to the HD24.


I found the HD24 to be incredibly easy to use, even before reading the manual. I feel that for the price, and especially considering the current low cost of hard drives, the HD24 should be a definite consideration for anyone looking to buy a multitrack hard disk recorder. As much as a tried, I could not get the machine to make a mistake, or give me an error message. I also have not found one person here at the Conservatory who has had any problems with the machine. Because of their reliability we are planning on installing them in all of our studios.

Second Opinions:

Based on their reliability, user interface, and storage medium, we are incorporating the HD24 into our studios at the Conservatory, and therefore, into our school curriculum.

After comparing the high-resolution (96 kHz) recordings to the standard resolution (44.1 kHz), I found the high-resolution recordings to be far less fatiguing to my ears at the end of the session.

-Michael Jones, Director of Education/Audio Recording & Production Instructor

What I like about the HD24 is the total ease of use – if you are even slightly familiar with digital multitrack recorders, you can use the basic functions of the machine without even looking at the manual. If you are familiar at all with ADATs, the HD24 will be a breeze to learn and use. During my session, I could create a new song, name the song, and be rolling in less than 30 seconds. I would highly recommend the HD24 for remote recording.

-Tony Nunes, Audio Recording and Production Instructor

Besides the HD24 being so easy to use, I found the high resolution to sound much less phasey, more open and natural sounding, and with improved transient response as compared the standard resolution. The unit is well-built and easy to hook up, and I found the commands and functions to be very logical and intuitive.

-Dale Epperson, Conservatory Technician/Owner of Old School Audio