Alesis ADAT HD24 Digital Hard Disk Recorder

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Input Connectors: 24 balanced 1/4 in. TRS jacks

Nominal Input Level: +4 dBu (1.23 VRMS) = -15 dBFS

Maximum Input Level: +19 dBu (6.9 VRMS) = -0 dBFS

Input impedance: 10 k ohms

Output Connectors: 24 Pseudo-Balanced 1/4 in. TRS jacks

Nominal Output Level: +4 dBu (1.23 VRMS) = -15 dBFS

Maximum Output Level: +19 dBu (6.9 VRMS) = -0 dBFS

Output impedance: 220 ohms

Signal to Noise Ratio: 103 dB A-Weighted, Analog In to Analog Out

THD+N: < 0.003%, Analog In to Analog Out

Frequency Response: 22-22 kHz 0.50 dB, Analog In to Analog Out

Power consumption:
60 Watts Max (100-240 VAC/50-60 Hz)
20 Watts Max in Stand-By Mode

Size (H x W x D): 5.24 x 19.0 x 13.5 in. (133 x 483 x 342 mm)

Rack spaces: 3 spaces

Weight: 21 lbs. (9.6 kg)

All measurements done over a 22 Hz - 22 kHz range with 1 kHz sine wave at 18dBu (-1dBFS) input. Impedances are measured at 1 kHz.
If you have additional warranty questions, please contact the manufacturer at 401-658-5760
(139 ratings)
Submitted September 2, 2009 by a customer from
"Nothing better/more felxible around!"
Verified Customer zZounds has verified that this reviewer made a purchase from us.
This review has been selected by our experts as particularly helpful.
The is NO NEED to look any further than the Alesis HD24-family of multi-track recorders if you need a fully featured, TRUE 24 TRACKS, the ability of recording all 24 tracks at 44.1 / 48 kHz (16 or 24 bit), or TWELVE TRACKS at 88 / 96 kHz (16 or 24 bit); 24-bit recording IS THE DEFAULT Easy plug in of the 1/4" unbalanced analog cables or the 8-channel ADAT Lightpipe Toslink opticaal cables; there is more than enough room to insert or remove ANY of the analog cables, even if all 48 jacks are full... the spacing, both vertical and horizontal, make it easy for people with "fat fingers" (like myself) to work with a single or group of cables w/o having to remove a bunch of others. The audio quality EXCEEDS what is stated in the manual, in as far as S/N ratio, noise floor, analog "inter-track bleedthrough", and so forth. I have in excess of 500 hours of use on this recorder, even though I only bought it in late Juy of '09! Lightweight, very portable, small in stature (3U rack height), no need for extra hard drive cooling (see above comments!), low power draw for those interested in energy savings (performing a drive-to-drive COPY only requires 25.73 watts (measured at my test bench), MIDI control, Ethernet capability for use on the Net (or to transfer songs to/from a PC, although I recommend buying the Alesis 1394 Fireport unit for this unless you have a LOT of time on your hands!); you can daisy-chain up read more to FIVE of thses units, giving you a total of 120 TRACKS in full sync with each other (!!!), word-clock input if you have a MTC unit controlling all of your equipment like my Studio does; the ability to upgrade the recorder's firmware via Ethernet or MIDI; being able to edit recordings... with the ability to UNDO an edit which did not go as well as you wanted it to; the ability to perform PUNCH-IN overdubs w/o the need for a seperate track (although you COULD use an unused track if needed); record in 2 / 4 / 6 / 8 / 16 / 24 tracks at both 44.1 and 48 kHz @ 24-bit (DEFAULT BIT RATE... 16-bit is OPTIONAL). PLUS if you have older tape-based Alesis ADAT decks, you can simply plug them in to the new HD24 and either "archive / make a safety copy" of the tape, or transfer the tape to digital storage, since tapes can be easily damaged or be partially erased from being near a magnetic field when stored!)... Just buy this unit! You will NOT regret is at all! The new generation units are being shipped with an 80 GB hard drive, which gives you MANY, MANY hours of recording time, even at 24 tracks! Buy a 500 GB Seagate or Hitachi DeskStar (my professional choice) for around $150 shipped, and now you have PLENTY of "archival storage", which I recommend; but extra caddies (they come with a dust proof storage case), and buy MORE 500 GB drives, so that you can have "libraries" of backed-up material, maybe one drive for each artist you work with. At WELL UNDER $200 for a 600 GB drive and caddy, you cannot go wrong! This unit is durable, easy to use, simple to "plug in" to ANY modern mixer that has a send/receive (or "Insert") jack for each track, and you now can record a PURE SIGNAL TRACK PRE-FADER/PRE-EQ/PRE-EFX, and then transfer the tracks to a PC or MAC for editing. This unit is 100% backward-compatible with ANY of the old tape-based ADAT decks, so you lose nothing by adding this recorder to your existing equipment (or upgrading it); and the BEST past of all of this is tere are no "virtual tracks" to deal with! So,= you don't have to buy an 8 or 16 track mixer/recorder and then have to play around with "virtual tracks" to get full 24 track capability! 100% ProTools compatible, and it also gives you .WAV << AND >> .AIFF recordings (yes, they're BOTH recorded... no need to choose), so it can work with ALL PC or MAC software! 8-channel ADAT Lightpipe optical connections to other decks, equipment, or computers for the ultimate in studio gear connectivity and compatibility. Try finding ALL of this somewhere else without having to buy multiple pieces of equipment which would all cost more than this recorder... YOU SIMPLY CANNOT! Thanks for reading ALL of the details on what this recorder is able to accomplish IN A SINGLE UNIT!!! Nothing here has been "embellished" or "untrue"... and any opinions are my PROFESSIONAL ones, coming from OVER 35 years of audio engineering!

Even if you're only using 44.1/48 kHz sampling rates, the 24-bit (with 128x oversampling on the A>D and D>A sectionas), the result you get is as close you can get to a 24-track ANALOG recorder... at a fraction of an analog recorders' price (and if you can find one without taking out a 2nd mortgage on your house!). As an audio engineer of 35+ years, as well as someone who has use the original 8 track tape-based ADAT decks, I have literally been floored by the clarity of the recording and playback audio. Nothing on the market comes close to how this unit sonically! Totally transparent audio-side, the ability to hook up FIVE ADDITIONAL HD24 units with simple Lightpipe cables... or to usse it to work, OUT OF THE BOX to work with existing tape-based ADAT decks... the "backwards compatibility" and the audio clarity makes purchasing a "no brainer".... novices or multi-decade (like myself) experienced studio engineers would both love this unit.

The HD24-series recorders now come with an EIGHTY GB hard drive, wich gives you DOZENS OF HOURS of full 24-track recordings without having to bu another hard drive; You can pick up Hitachi (recommended by our studio) ot Seagate (2nd choice here) 500 GB IDE/EIE/PATE drives for UNDER $100 at plaes like Best Buy,, and so forth. The only feature I would like to see is a drive caddy able to use the SATA/SATA 300 interface type of drives (Alesis said they are working on this as of the time of this review being written); SATA 2 Terrabte drives can be had for $150, and this would give an user ALMOST 1,000 HOURS OF 24-TRACK RECORDINGS(44.1/48 kHz)! The ONLY two reasons I am not giving this usit a full 10 in this caagory is that there is a problem with the WD Caviar Blue 320 GB and larger hard drives and tis unit; they simply do not work with each other. Again, Alesis is working on trying to figure out what the problem is, as every other WD high-capacity drives wrk just fine! The 2nd reason is the SLOW Ethernet connection... 10 MB/Sec???? That's like someone getting 56k dial-up for an Intermet connection! This could EASILY be changed to a 10/100 or a 10-100-1GB/Sec Ethernet board! Let me tell you, you MUST transfer 1 track at a time (!!!), and to transfer a 4 hour to a PC/MAC takes almost 6 hours. Otherwise, a basic REMOTE CONTROL for operating the transport, the ability to name/rename already recorded file, being able to put 99 songs (max.) to a single drive. AND being able to make an ERROR-FREE copy from 1 hard to another I use this feature (I record a band I do all of their audio work for them) when I record a 2 -> 3 hour show, and before I leave the venue, I can back u what I just recored onto a 2nd hard drive in less than 30 minutes (a 24-track 48kHz recordig, mind you!

Ease of Use
Some of the "Utility" functions can seem a little daunting, as the owners manual has not been updated for several years, and major upgrades have been made to the "first geration" of the HDS24 to the current model being shipped. Works with 32-bit and 64- bit versions of Vista withut a problem.

I recently made a "test" recording, making a 15 hour / 24-track / 48 kHz CONTINUOUS "SONG"; after the 15 hours were over, I properly removed the recording drive bay, sid the top off (that's how you mount a new HD into the caddy)... the Hitachi PATA hard drive was only slightly WARM to the touch... nowere near hot in any way; using an infrared thermometerm showed the HOTTEST area was only 86.229 degrees F! No, the caddies do NOT have an internal cooling fan! When a drive is in use, a VERY QUIET high CFM fan turns on, and it pulls fresh outside air into caddy across the top and bottom of the drive; this is a simple idea, yet it works wonderfullt;

The $1,600 price almost every sells it for is VERY reasonable for ALL of the performanc you receive; BUT was selling the HD24 for $1,284... and BEAT THAT, and I paid just under $1,220 WITH FREE SHIPPING and NO TAX (unless you live in NJ)! The SOUND and FEATURES comments, combined with the price I paid, leaves me no choice than to rate this section a full 10! Even if the unit was $2,000 street price, it would STILL be a bargain for all it does. Don't believe me? Download the .PDF files, and read all about this fasntastic 3U tall rack-mountable unit that weights less than 25 pounds (with BOTH drive caddies filled!).

Manufacturer Support
I had 2 questions, and once the Tech Support people came on the line, they had the EXACT ANSWER WITHIN 1 MINUTE Of BEING ASKED TE QUESTION! You don't that type of knolegde, from ANY company (I've had similar experienced with Sony Creastive Medis when I install an update on their PROFESSIOAL audio and audio/video editing software!

The Wow Factor
The unit is NOT "fancy" to look at... it does what it should do with the minimum of "glitz or glamor", which actualy makes it MORE appealing to the eye. THE ONLY "CON" I HAVE IS THE NONE OF THE "CONTROL BUTTONS" ARE "BACKLIT", WHICH SOMETIMES CAN MAKE IT DIFFICULT TO SEE IF YOU ARE GOING TO PRESS THE CORRECT BUTTON(S) << IF >> IT'S LOCATED AT A VEMUE THERE THE MIXER (ETC.) IS IN A DARK AREA... but after you've worked with the unit for 3-4 on-the-road gigs, you've become well aware enough to know what button does what! Personally, I use it in both "on the road" as well as in my own professional post-production Studio; in the Studio, where the lighting is much better, the function buttons are quite easy to see, so knowing where the not-very-often-used controls are becomes second nature in a VERY short amount of time. There are TWO main "visual" sections to the front panel: one being the color-coded "RECORDING LEVELS" for each of the 24 tracks, and the "present time / information / other info" readout"! These are lit bright just enough so that they are not distracting, yet EASILY VIEWED by being laid out correctly and being "just the perfect size" for the person using the HD24! The control button "areas", for utilities, editing, and so forth, are, in my PERSONAL and PROFESSIONAL opinion, laid out so that you do not have to search for them... the same goes for how the "info readout" allows you to QUICKLY and EASILY look at what you ned to know! Inculded with the HD24 is a (optional use) "transport control" unit; this allows the user to be able to stop, start, FF/REW, and to begin recording from about 6 feet away from the main unit. I needed it to be a little longer, so I simply went to Radio Shack and bought a 10 foot "headphone extention cable" (with a 1/4" jack and plug), and this allowed me to place the transport control in a much more convenient place on my editing console table. This unit is small (6" wide by 4" high by 1" tall"), yet it allows you to perform ALL of the "transport" controls, plus RTZ, setting NEW and/or additional "Location Points" on the fly (or when the unit is NOT "moving" (there is NO "Pause" button on the HD24, as it is not needed!), etc. The buttons are the same size as the ones on the main unit, so it's not like you're going to hit a button by accident because of button size). The unit/front panel/remote transport are dark grey and black, with slightly blue-tinted white lettering on the "readout window"; the 24-track vertical recording levels are color-coded, so you don't need to squint or have to look REAL CLOSE at the main unit to see if the signal level is getting too high; BOTH drive bays are VERY easy to get to, and the drive caddies lock into the unit without any problems; overall, if the HD24 mounted in either a portable case for "at-the-venue" work, or in a rack for in-studio work, the recorder is not an item which (when powered off) draws one's eyes to it... and when it IS powered up, the display brightness is neither too bright not too dim as to not allow you to view any other effects units which may be mounted just above or below the recorder. THE PHYSICAL SIZE AND WEIGHT ARE ALSO << PERFECT >> ! It is only THREE "rack units" tall, and weight in (with BOTH drives installed) at about 23 pounds! So it is easy to mount in a portable 4U carrying case, and be able to placed almost anywhere when it's being used at a venue.

Musical Background:
Over 35 years as an audio engineer / live recording engineer

Musical Style:
Jam Band (Grateful Dead, Phish, Moe, etc.)
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