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Mackie SDR24/96

24-track Hard Disk Recorder By Paul White
Published December 2002

Mackie's entry-level hard disk multitrack gives you all the convenience of hardware, but also allows you to transfer tracks to your computer via USB for more detailed editing and mixing.

Despite the inroads software-based systems have made into recording at all levels of our industry, hardware still wins hands down when you're working with multiple musicians in a traditional studio environment. Furthermore, while all-in-one workstation solutions are cost-effective and compact, most are unable to record on all tracks simultaneously and, while internal effects and dynamics are commonplace even on cheaper models, this is invariably balanced by a paucity of connectivity options which seriously limits the way in which outboard equipment can be patched into the system. For maximum flexibility then, the best solution is to use a separate multitrack recorder and mixer, where a patchbay can be used to connect rackmount processors and effects where these are deemed necessary.

Mackie SDR24/96 digital multitrack recorder.Photo: Mike CameronMackie's first foray into digital multitracking was the HDR24/96, a versatile and powerful stand-alone 24-track recorder with the undeniably attractive feature of being able to work with a monitor for graphical editing. The HDR24/96 is still the flagship of the range and has since been joined by the MDR24/96, offering a slightly reduced feature set and no monitor option. The newly released SDR24/96 is now the entry-level model of the range price-wise, but in some ways it is more attractive than the MDR24/96, not least because it comes with both analogue and ADAT-format I/O as standard — with the earlier machines, optional I/O interfacing cards had to be fitted.

A New Entry Level

At its simplest, the SDR24/96 can be considered as a digital replacement for a traditional 24-track tape recorder, but with the added benefits of in-built MTC and SMPTE sync (master and slave modes), cut/copy/paste audio editing and multiple levels of undo. It can record via its analogue inputs at sample rates of 44.1kHz, 48kHz, 88.2kHz or 96kHz and resolutions of 16 or 24 bits, though using the higher sample rates limits the number of tracks that can be replayed simultaneously via the digital output to 12. Currently the ADAT inputs don't support 96kHz recording, though a future software update is apparently planned to address this. The ADAT nine-pin sync ports are also not currently active, again pending a software update. Good-quality, though non-esoteric, converters are used, giving minimal distortion (0.005 percent at 1kHz, -1dBFS) and a frequency response flat from 20Hz to 20kHz within 0.5dB. All this equates to a dynamic range of 108dBA, with crosstalk between channels better than -90dB.

Mackie SDR24/96 £1999
  • Solid, simple operating system.
  • USB and removable drive backup.
  • All analogue and digital I/O included.
  • Comprehensive sync options.
  • Several features are not yet operational.
  • D-Sub connectors are less convenient than standard TRS jacks, unless you're prepared to buy six ready-made cable looms.
The SDR24/96 is a solid, simple-to-use alternative to a multitrack tape machine, and has a practical array of backup options and edit facilities. Optional remote control units are also available. Several features have yet to be supported, but there's nothing to prevent you using the machine in most normal applications.


The included internal 20GB hard drive stores around 90 minutes of 24-track audio at a 48kHz sample rate, and slightly more at 44.1kHz. As with the other Mackie recorders, audio data can be backed up to the optional Mackie Media M90, a hard drive fitted into the removable front-panel drive tray. The Mackie Media Project 2.2GB Orb cartridge drive isn't yet supported, but, once again, a software update is apparently on the way to fix this. Recording is possible directly to removable hard drives, but the Orb drive will be for backup only. It is also possible to transfer data to a computer via the SDR24/96's built-in USB port, and, though this may be relatively slow, the standard WAV file format used by the machine means that recorded files could be loaded into many of the common sequencer or multitrack audio software packages for further editing. It also provides a means to back up projects to CD or DVD if your computer has these facilities.

All the necessary controls are on the front panel, though an optional remote control device, the Remote 24, can be connected via a rear-panel Ethernet-style socket. When the ADAT sync ports are supported by the software, they should allow sample accurate sync when transferring files to or from ADAT-compatible systems. There's also a standard serial nine-pin socket (EIA RS422, compatible with Sony nine-pin) for integration into professional editing systems, and MIDI connectivity to provide MIDI Machine Control (MMC) and MIDI Time Code (MTC) sync both in and out. The power supply automatically adapts to worldwide power sources between 100 and 240 Volts AC, but for professional studio use the manufacturers recommend using an uninterruptible power supply, as power failures during certain operations can result in data loss, as with a computer.

For analogue I/O, the SDR24/96 uses a series of six 25-pin D‑Sub connectors (balanced at +4dBu nominal, +22dBu maximum) wired to the widely adopted Tascam analogue standard.For analogue I/O, the SDR24/96 uses a series of six 25-pin D‑Sub connectors (balanced at +4dBu nominal, +22dBu maximum) wired to the widely adopted Tascam analogue standard.Photo: Mike CameronUnlike its closest competitor, the Alesis HD24, which uses standard balanced quarter-inch jacks for the analogue I/O, the SDR24/96 uses a series of six 25-pin D‑Sub connectors (balanced at +4dBu nominal, +22dBu maximum) wired to the widely adopted Tascam analogue standard — this will prove less convenient than individual jack or XLR sockets for many home musicians.

Digital I/O is via three pairs of ADAT lightpipe connectors. With independent hardware of this type, synchronisation is a key issue and, given that the SDR24/96 is an entry-level machine, it seems to have most bases pretty well covered already, albeit with ADAT sync still to be added. Already the machine supports MMC and MTC, and has SMPTE In and Out connectors on quarter-inch jacks, allowing it to generate or sync to timecode. For tighter integration with all-digital systems, it has word-clock in and out on standard 75Ω BNC connectors. Finally, a further quarter-inch jack socket can be used to plug in a basic footswitch for punching in and out, starting or stopping (you set which in the Setup menu).

The Front Panel

Housed in a 3U case, the styling of the SDR24/96 follows that of its predecessors, with 24 generously sized record/playback level meters and a separate Record Ready button beneath each. The mains power switch is placed to the left of the drive bay, where I found that it was rather too easy to operate accidentally. Once, when selecting low numbered tracks for recording, I accidentally switched off the power with my knuckles — not something you'd want to make a habit of!

The removable drive bay (no second drive was provided with the review model) occupies the lower left-hand side of the machine, while the right is given over to a large numeric SMPTE time display and a two-line LCD window for accessing setup and project information. Bar and beat display is currently unavailable, but it would be sensible for Mackie to add this, as it would make editing easier in some instances. Fourteen further buttons access functions such as location and editing, and four Select buttons below the screen allow on-screen options to be accessed, in combination with left/right arrow keys. The transport buttons are gratifyingly chunky, addressing the familiar fast wind, stop, play and record functions, while a handful of LEDs adjacent to the SMPTE window provide information as to external clock status, sample rate, bit depth, timecode lock and varispeed on/off. There's also an error LED that should only come on during times of serious abuse!

Unlike tape, where you simply thread up and then record until you run out of tape, the SDR24/96 organises its audio files into Projects, where one project might typically be one song. A default Startup project is available if the machine has not been used before, otherwise you have to create a new project, which can be named of course — up to 20 characters. After recording, projects should be saved, because, although audio files are automatically saved as they are recorded, edit data and other project settings are only stored when you save a project. However, before you can even start a project, you need to configure the machine to tell it what sample rate and bit depth you wish to work at, what sync options are needed, whether you're using analogue or digital I/O, and how you want the track I/O mapped — by default, input one feeds track one and so on, but this can be changed to a custom routing if you wish. All this is done via the Setup menu, where you can also define a source of timecode to be chased. All the standard MTC/SMPTE frame rates are supported, including 29.97 drop and 30 drop, though the drop-frame options are only likely to be used if you're working in a specialised video environment. The Setup menu is also used to access the varispeed option, which you may need when recording with a house piano that is slightly off concert pitch, for example.

Once a recording has been made, the Copy Project command can be used to clone the Project to the backup drive (or to another location on the main drive). Unwanted projects can be deleted, but, curiously, the Purge option in the Project menu is not yet available. When enabled, this will delete any audio files not used in the current project in order to conserve disk space.

Set The Controls

Because there's no tape to wind, the designers have included the option to 'spool' through audio at different rates. Hitting a fast wind key once builds up to 20 times the play speed after four seconds, but you can press it twice for 60x speed, three times for 180x speed, four times for 540x speed or five times for 1620x speed. That should satisfy even the most impatient engineer! Hitting either fast wind key, Stop or Play during recording punches out of record, so if you panic then there's a fair chance you'll hit the right key. Recordings are automatically saved to disk when Stop is pressed following a recording. Hitting Stop twice in succession locates directly back to the start of a project. Stop can also be pressed and held for a second or more to put the transport into audio scrub mode, where the fast wind buttons are used to control the scrubbing direction. The scrubbing speed appears to be fixed at around twice the normal play speed so you still hear the music well enough to locate a particular section. However, a proper variable-speed scrub might have been useful for locating edit points. Pressing Stop again returns the transport to normal operation. Recording on selected tracks is activated by pressing Record and Play in the usual way and a one-button punch mode can be set up for those brave souls who prefer to punch in using the Record button alone.

 Options & Pricing 
  • SDR24/96 24-track hard disk recorder, £1999
  • Remote 24 remote control, £249
  • M90 preformatted EIDE drive for direct insertion in SDR24/96 drive bay, £199
  • Kingston-style drive tray (allows standard EIDE disks to be used in the SDR24/96 drive bay), £49
  • Project ORB-drive package: £249
  • All prices include VAT.

Monitoring is very much like using a tape machine and, unlike some software systems, there's no discernable latency. All Input mode routes all the inputs directly to the outputs and shows their levels on the meters, and its the mode you'd normally select when getting the record levels right as the band rehearses. Auto Input follows the familiar tape paradigm, where only tracks armed for recording are monitored. During playback, the 'off-tape' sound is played via the outputs, but this immediately switches to input monitoring when you enter record. Unarmed tracks always monitor the 'off-tape' signal so that you can keep time with what you've already done when recording overdubs. A dedicated Auto Input button makes selecting this most vital of functions as easy as it used to be on tape machines. Rehearse mode allows automatic drop-ins to be practised, with the monitor mode switching automatically at the punch-in and punch-out points, but no recording actually takes place.

The SDR24/96's design allows for each of the 24 tracks to have eight virtual tracks, but these are not available in the current software version — once this is added, the Track button should let you choose between virtual tracks. Similarly, Auto Take, a mode where successive takes automatically fill up successive virtual tracks, isn't yet functional. The Track menu lets you name tracks if you are that organised, and when you have a definite 'keeper' you can activate Safe mode to lock all the tracks in a Project from being overwritten. Another Track menu function mentioned in the manual, but also unavailable at present, is the facility to mute playback on unwanted tracks, but this is no big loss, as I know of few mixing consoles that aren't equipped with mute buttons.

Up to four locate points can be set directly via the Setup menu as discrete time locations or entered on the fly (transport stopped or running), where locators three and four are used as edit in/out markers. A transport time offset can also be entered for when the machine is being used with a timecode source that starts at, for example, one hour rather than zero, as is common practice. Relative offsets can then be subtracted from this global offset amount, again via the Setup menu, where locate points are offset by the same amount when this facility is in use.

Autoplay, when active, causes the machine to enter play mode immediately after a locate operation, and locating is pretty quick — after hitting the Locate button, the four locate points show up on screen so you only have to push the Select button below the one you want and you're there straight away. Locate points can also be used to create a looped playback section, for example when you need to rehearse a part, or to set the region where a drop-in is to happen automatically on armed tracks at the locate points. Other locate-related facilities include the ability to set pre-roll and post-roll times for locating or automatic drop-ins.

Editing Facilities

With tape, if you don't like what you just recorded, you have to record over it, but the SDR24/96 has a handy Delete Last function as well as multiple levels of undo. The machine keeps a history list and Delete Last can only be used if the recording was the last thing to be added to that list. Alternatively, you can use the Edit/Undo button to undo the last recording and return to the previous take — a facility that all analogue tape users must be seriously jealous of! Indeed, depending on the sizes of the edits in the 'history list', up to 99 levels of undo are available, and if you come to a recording in the history list you have the option to undo that too or leave it intact as you move further down the list. Starting a new project or powering down the unit clears the history list, so it's wise not to leave any pending undos undone for too long!

 Test Spec 
  • Mackie SDR24/96 OS v1.08.

Though the editing functions are fairly simple compared with what a computer-based system offers, they do allow arrangements to be changed, sections of audio to be copied or moved and so on. Locators three and four are used to mark edit points for delete, cut or copy operations, and, unlike some competing systems, there's a 'splice' option, which means that when you remove a section of audio, the material after the edit moves up to fill the gap. Normally this only makes sense when editing across all the tracks you've recorded so far, but it's a handy way of removing a verse. Similarly, when you come to paste a section of copied audio from the clipboard, you can paste over the material at the edit destination (non-destructively of course) or you can again select splice so that the material moves up to make way for the audio you're inserting. Again this is very useful if you want to rearrange a song without having to re-record it all, and because these operations are added to the history list, they can be undone if they don't work out as planned. I checked out both replace and splice copy modes and found they worked exactly as described in the manual. An additional Place edit facility, which Mackie claim in the manual is able to copy audio from another audio file and place it anywhere in the song, is not yet implemented.


All audio drives used in a random access mode are prone to fragmentation, so a Defrag option is included in the Setup menu. Unfortunately, when you try to select it, you get a message saying it's not been implemented yet, but again it's apparently being added in a forthcoming software update, as is a command for mounting additional drives. The System menu also accesses the USB file transfer facility function, where the SDR24/96 appears as an external mass storage device on the computer desktop, allowing project folders to be copied to or restored from the computer's hard drive. You can't record while USB transfer is taking place, and when the task is complete the SDR24/96 asks you to reboot before you can continue using it. I checked out saving a project via USB and it worked fine with no driver software needed — rebooting only took a few seconds. If you open the audio files folder, you'll find a separate file for each take recorded onto the machine, so assembling these in a sequencer could be problematic if you do a lot of retakes or punch-ins. What would be useful (and I don't know if this is planned for a future update), would be a simple and automatic way of bouncing all the fragments of tracks into complete track-length files so that they could be dragged straight into a sequencer with no complications.

Formatting is also taken care of in the Setup menu. If you're worried that your drive may be getting too fragmented, there's a Load meter that shows how hard the CPU is working to keep everything together. As you might expect, if this goes past 100 percent (well beyond its typical loading), the system will grind to a halt and display an error LED. As defragmentation isn't implemented yet, there is little you can do if you get into this situation other than to wait for the next software update and see if it has been added. As potential users may have to sell their pocket organisers and studio clocks to afford an SDR24/96, the machine thoughtfully includes a date and time function.

Running The SDR24/96

As a tapeless tape machine, using the Mackie SDR24/96 is a breeze and, even at 'sensible' sample rates, the recording quality via the analogue inputs is excellent. As mentioned earlier, I feel the mains switch has too soft an action and is inadequately recessed, making it all too easy to power off the machine when arming tracks for recording, but once you've discovered this for yourself you'll probably ensure you don't do it a second time! The transport controls have a nice 'professional' feel to them and the fast wind speed options are to be welcomed. Setting and locating to markers is easy, despite four locates per project (plus return to zero if you hit Stop twice) being a little on the stingy side, and copy/paste editing proved to be very straightforward provided that you have a good sense of timing when it comes to setting locate buttons. In any event, you can use rehearse mode to see how your edit will sound before you commit yourself, and locate points can be adjusted accordingly, but it's always easiest to get it right first time! Having the option to insert copied sections using the 'splice' mode makes changing song arrangements really quite simple, and if it all goes horribly wrong then there's always the multiple undo function.

I was a little disappointed to find the machine shipping with some features not yet active, specifically virtual tracks, ADAT nine-pin sync support, the disk defragmentation routine, mounting of additional drives, and the Purge facility. You could easily live without most of the unsupported features and, indeed, some competing machines don't offer these anyway, but the disk-related facilities need sorting out quickly.

Checking out the MTC chase facility proved the machine could lock to MTC as well as dish it out. Once the Timecode Chase button is armed, the Play light flashes until a valid MTC signal is received, then off it goes. I'd estimate that lockup took around three seconds from the MTC source being started, and scrolling the sequencer (which I used as my MTC master) to a new location didn't phase the SDR24/96 at all — playback just stopped for around three seconds until the transport had locked to the new location.

All In All

Although it doesn't offer the visual editing of the HDR24/96, the SDR24/96 is still a solid, professional-feeling machine that can run rings around a tape machine, not just in permitting editing, but also by providing multiple levels of undo and comprehensive sync facilities. There are a number of 'yet to be activated' features, so make sure you get the latest OS update from Mackie's web site, but the SDR24/96 is still a very capable and solid machine. The sound quality is good at any sample rate and, though I prefer to work at 24-bit rather than 16-bit when possible, I can't hear any significant difference between 44.1kHz and 96kHz, even on quite demanding material. Maybe when you have the best studio building, the best mixer, the best mics and everything else, it may make a difference, but in the project studio I don't think there are many reasons to use it.

The Mackie SDR24/96 competes favourably on price with any of the serious hardware 24-track recorders in the UK, yet offers an enviable feature set (including built-in digital and analogue I/O), better-than-average editing and good sync facilities. The USB transfer option is easy to use and lets you move projects back and forth between the recorder and a suitable computer and, of course, there's the front-panel drive bay for making backups. Despite the currently unavailable features, nothing will stop you from making high-quality recordings with the minimum of head scratching. The manual is typically Mackie, in that it's clear, concise and friendly, and during the course of the review I had no operational problems with the machine at all. If you don't want to go the computer or integrated workstation route, the SDR24/96 has much to recommend it.

infop.gif See 'Options & Pricing' box.
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