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Alesis HD24 Hard Disk Recorder

It has been quite awhile since Alesis introduced the ADAT multitrack tape cassette recorder, changing the project studio landscape overnight by offering a relatively inexpensive way to enter the multitrack digital realm.

It has been quite awhile since Alesis introduced the ADAT multitrack tape cassette recorder, changing the project studio landscape overnight by offering a relatively inexpensive way to enter the multitrack digital realm.
Product PointsApplications: Studio

Key Features: 24-track, 24-bit digital recording; 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz sample rates; analog and digital I/O

Price: $2,499

Contact: Alesis at 310-821-5000, Web Site


+ Works flawlessly

+ Fully ADAT-compatible provides many features and functions in one box


– Some features still in beta

The Score: A worthy successor to Alesis’s ADAT lineage.
But, times change and the world of audiotape is slowly fading into oblivion, its popularity usurped by the ever more affordable hard disk.

Realizing it must adapt to the changing audio landscape, Alesis has developed and brought to market the HD24 ($2,499), a 24-track digital hard disk recorder with some interesting new ideas and features not found on its most direct competitors.


The HD24 is a three RU, rackmountable unit weighing in at a relatively modest 21 pounds. As its name implies, the HD24 is a 24-track digital recorder that records at 24-bit on standard IDE hard drives, even drives running at 5400 RPM. This allows for a cost per track that beats the previous ADAT tape format. Recording at 48 kHz, a 10 GB hard drive will give you 45 minutes of 24-track recording time. The test machine came with a 20.5 GB drive, giving me roughly 90 minutes to play with right out of the box.

It’s the way it writes data that makes the HD24 unique. Alesis developed a new method for storing data on hard drives, which it calls ADAT FST.

Traditional computers store information in fragments, taking your guitar solo, breaking it up into little pieces and storing it here and there so that the drive can fit as much information as possible. While this is fine for the traditional computer application, recording music in this fashion causes the drive to “thrash” around looking to reassemble all those scattered files into a music stream.

The HD24 writes in a more linear fashion, storing all the tracks of a song together. While this may lower the actual amount of data a drive can store, it makes life easier for the drive while allowing for quicker retrieval of data.

The hard drive is mounted in a removable caddy. This makes for simple drive swapping when you are trying to separate projects or if you find yourself filling them up at a rapid pace. Two caddies come as standard equipment so you will be able to keep both bays occupied should you find a need.

The machine is targeted at 44.1 kHz and 48 kHz sample rates. You can record at 88.2 and 96 kHz, but you are limited to 12 tracks and must use the digital inputs. There is an optional board available, the EC-2, which allows higher resolution recording through the analog inputs but the track limitation still exists. Consider this a fair tradeoff for the $1,999 price.

The specs include a signal-to-noise ratio of 103 dB (A-weighted) and a THD+N of less than 0.003 per cent with a frequency response of 22 Hz to 22 kHz.

The front panel does a good job of keeping you informed without overwhelming you, a worthy feat when considering the amount of information being conveyed here. It includes buttons for transport control, locate, editing, clock source, sample rate selection and the utilities menu, as well as a host of other functions. You will also find 24 10-segment, peak reading meters and an arming button for each track located below them. All settings you have chosen, as well as time, song and hard drive information, are shown on the alphanumeric display.

The rear panel features 48 1/4-inch TRS jacks (24 input, 24 output) as well as three sets of ADAT lightpipe digital I/O, each handling eight channels. If you are building from the ground up and plan on using an analog console, be sure to consider the cost of cables in your budget. Also included is the ADAT sync in for connection to the Alesis BRC, and sync out for connecting multiple HD24s together, MIDI in and out, word clock in for external clocking and plugs for the included LRC remote control, and a punch switch for those who like to go it alone.

The last and perhaps most interesting feature on the back is the Ethernet connection. This allows the transfer of sound files to your computer for complex editing as well as transfer via the Internet if you are working on a project with someone in another part of the world.

And if using FTP is too slow for your tastes, Alesis is working on a quicker way to move files to your PC. The manufacturer is currently beta testing new PC software and an external drive bay that would allow drive swapping. When it is time to transfer, just pull your drive from the HD24 and plug it into your PC. It needs to be pointed out that the HD24 drive being placed into a PC will not be the main system drive but a supplemental drive.

Software upgrades can be done via MIDI or through the Ethernet port if you would like to get it done a little faster.

Also included is the LRC (Little Remote Control), which contains the basic transport controls as well as buttons for loop and locate functions. If you desire to keep the HD24 in another room or just want more function at your fingertips, the optional BRC (Big Remote Control) is available.

In Use

My first experiment involved a simple transfer of some final mixes from my computer into the HD24. With my original setup, using a Mackie 24 x 8 mixer, use of the analog inputs was required and I fully anticipated some loss of quality during the process. But any degradation was minimal and would have been hard to discern in all but the most critical listening environments.

While I found the HD24 and Mackie to be a good combination, I really wanted the chance to record at 96 kHz to get a full appreciation of the machine. Fortunately, a solution appeared at the last minute when a friend purchased a TASCAM DM-24 digital mixing board and was gracious enough to allow me to experiment with it for a couple of days.

I later got a chance to revisit this test using the DM-24, which allowed for a digital transfer using the ADAT optical inputs. Comparisons between the original and this new version revealed some subtle differences, yet choosing a favorite was more difficult than expected. Chalk this up to the quality of the Alesis converters, a thought that revisited my mind many times during the sessions.

Preparing for some multitrack recording gave me a chance to get familiar with the interface and find some interesting facets of the HD24s functionality.

One example is the track setup feature. In a bid to save hard disk space, you choose how many tracks you are going to use before you start. The options are 24, 16, 8, 4 and 2 tracks when recording at 44.1 kHz or 48 kHz (12, 8, 6 and 2 tracks when using higher resolutions). I like the idea but would like the ability to add tracks in the middle of a project should the need arise.

And it quickly became apparent how important the locate feature is. If you do not use it, getting to different parts of a song becomes a bit tedious. Alesis chose not to adopt the same functionality in the rewind and fast forward buttons that most computer systems use. Instead, they work in three ways. Push once and the track rewinds (or advances) five seconds, hold it down and it will scroll, hold with the stop button and it will scrub. Let go and it will stop. Want to rewind back to the beginning? You will find life much easier programming locate zero rather than pushing the rewind button for a few minutes.

My next bit of fun involved the editing feature. I recorded some individual parts and imported some others, and then I spliced them together into a finished song using the copy and paste functions much like a computer. While performing the same task on a computer would be much more efficient, the HD24 proved useful as an editor.

Finally, I recorded pieces using all 24 tracks to see if it would groan or creak or give me the odd error message. I also paid close attention to the quality of the individual tracks to see if any of my hard work during the recording process was getting lost upon playback. The recordings were excellent, a big improvement on the original ADAT system and on par with systems I have often dreamed I could afford. The beauty is, this time I could. And try as I might, I just could not get it to do anything foul that was not my own fault.

Testing the second drive bay meant finding an additional hard drive. After some digging, one was secured and mounted. This made backups a simple, painless process. A welcome feature indeed.


Alesis is working hard to ensure the success of the HD24. Software upgrades have been quick in coming and the new EC-2 board option makes it even more competitive. Its user interface was a pleasure to deal with, leaving little time wasted on problem solving and more time making music. Sound quality was top notch, even at the lower sample rates that most people will be using. Add a MasterLink CD recorder and you have a quick, efficient way to steer your project from tracking to mixdown. Though it has taken Alesis awhile to come to the table, at least it showed up with a good hand.


Shure KSM 44, SM-57, Oktava MC-012 microphones; Mackie 24 x 8 mixer; TASCAM DM-24 digital; Event PS-6 monitors; AKG K 240 headphones; Monster and BLUE cables; TC Electronics M3000 digital processor, FMR RNC compressor.