What's Up with DAT?

The use of affordable multitrack hard-disk recorders is sweeping the globe, but there's a tape-based technology that's taken for granted yet rarely used
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The use of affordable multitrack hard-disk recorders is sweeping the globe, but there's a tape-based technology that's taken for granted yet rarely used
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The useof affordable multitrack hard-disk recorders is sweeping the globe, butthere's a tape-based technology that's taken for granted yet rarelyused to its full potential: DAT.

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DAT has become a universal medium for sharing digital audio. Despitestiff competition from CD-R and CD-RW, DAT continues to outperformother mastering formats and shows no signs of stopping.

The suggested retail prices of DAT machines varies widely-from $900for a no-frills portable to $11,000 for a fully loaded, time-code-readystudio unit. In this article, I will examine a handful of familiarrecorders that are within the budget constraints of most personalstudios. But first, let's have a look at where DAT came from and theinteresting things you can do with it.

WHEREDID DAT COME FROM? In 1987, the year DAT machines began to appear atindustry trade shows, home recording was much different than it istoday. The Amiga, Atari, and Macintosh computers were au courant forelectronic music, the cassette multitrack recorder was king, and mostpeople didn't have a .com address on their business cards.

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The choices for an affordable 2-track mastering deck were alsodifferent. Besides analog reel-to-reel and cassette formats, there wasBeta and VHS Hi-Fi, as well as the Sony PCM-F1 digital format. With theless expensive analog formats, you had to use noise reduction to getoptimal sound; with VCRs, you were stuck with an unpleasantcompression/expansion noise-reduction scheme that the user couldn'tdisable; and PCM-F1 was sometimes unreliable and sonically not toodesirable.

AND ALONG CAME DAT DAT machines combine a couple of technologiesfamiliar to our circa-1987 home recordist-the videocassette recorder(VCR) and a pulse-code modulation (PCM) processor. DAT machines storedigital information on tape via helical scanning using a miniaturizedrotating head. This technology was originally called Rotary-head DAT,or R-DAT for short. (Also in development at the time, though nevercommercially released, was a system called Stationary-head DAT, orS-DAT.)

Although DAT was originally intended as a consumer-oriented digitalreplacement of the ubiquitous Philips analog cassette tape, its successwas nipped in the bud primarily because it could be used to be makedirect digital copies of compact discs. The U.S. recording industry,with the help of Congress, immediately sued Sony to prohibit sales ofDAT gear in the United States and lobbied hard for a copy-protectionscheme. The result was that individuals who wanted an early DAT machinehad to acquire a nit through the gray market if they wanted to avoidthe copy-protection circuitry. This, of course, meant that you'd haveto take your machine to Japan or Europe if it needed servicing-not verypractical for most consumers.

As it turned out, audio professionals found DAT to be more stable,easier to use and maintain, and better-sounding than the PCM-F1 format,and thus DAT survived. In fact, "professional" units even allowed theuser to defeat the copy protection. Today DAT is still the most common2-track recording medium used by pros, not to mention the legions ofmusic fans that occupy the "taping section" at rock concerts.

In the beginning, DAT brought promises of better-than-CD audioquality, an end to wow and flutter, and a reliable digital format thatdidn't require a separate VCR. Of course, in these days of 24-bit, 96kHz hard-disk recording, mere "better-than-CD quality" is not the drawit used to be. Still, DAT continues to provide a cost-effective mediumfor high-quality 2-track recording.

STAYING POWER To many home recordists in the early days, DAT seemedlike a transitional format. The biggest question was, "How long beforeI have to change formats again?" The question is still valid today,because everyone can see the writing on the wall regarding tape-basedmedia: affordable, random-access, disk-based recording formats areeverywhere, so why invest a grand or two in a deck that will beobsolete in just a few years?

For starters, digital audio tape has proven to be a robust, yetinexpensive and compact, medium for storing sound. Thanks to thepopularity of the DTRS (which uses Hi-8 video cassettes) and ADATformats, tape will be with us for a while longer-especially those of uswith huge DAT, ADAT, and DTRS archives. And in the age of hard-diskrecording and CD-RW, the mighty DAT machine still offers features thatare unavailable in any other format: up to two hours of full-frequencydigital audio without compression; high-quality, low-cost reusablemedia; and compatibility and portability (every 16-bit, 44.1 kHzdigital audio tape can play in any DAT machine, including the portableones).

LENGTH IS EVERYTHING With DAT you can record up to two uninterruptedhours of music, at a higher resolution than the average CD. If you wantto double the amount of record time (and audio quality isn't an issue),the ability to record in Long Play (LP) mode may be a determiningfactor in your choice of a DAT deck.

Although there are 180-minute DAT media on the market, manufacturersof DAT players for audio use recommend against using such tapes (seethe sidebar "All DAT Media Are Not Created Equal"). If you need fourhours of 44.1 kHz, 16-bit audio record time, Tascam's DA-302 dual DATmachine ($1,875) is the ticket. In Continuous Record mode, it willautomatically switch to the second tape once the first has been fullyrecorded. It can also do this in Long Play at 32 kHz, yielding a totalof eight hours of record time. Need more than that? Tascam claims youcan hook up several DA-302 units in series to get an amount of recordtime limited only by your budget. In addition, each DA-302 tape wellcan be used independently thanks to the separate S/PDIF input/output,allowing you to dub off a copy from one side of the machine whilerecording with the other. The unit can also handle high-speed dubbingduties.

DAT FACE That traditional-looking tape-deck exterior of the DAT unit(with play, pause, record, fast forward, and rewind controls) beliesits plentiful yet easy-to-use features that make DAT a powerful 2-trackformat. For instance, you can search for songs on your cassette deckusing the Automatic Music Search feature, but DAT allows you to searchfor specific songs using program ID numbers.

As with other gear, the overall design of the DAT machine's userinterface determines the way the product can be used. For example, if aparticularly useful feature is embedded deep in the menus, it'sunlikely that the feature will get much use. Therefore, it's importantto know which features you will need in a DAT deck before you goshopping for one.

THE RESOLUTION ENVELOPE One factor that will determine the "sound"of a particular digital recorder are its A/D converters. Most of theunits I tested for this article have comparable-sounding converters(I'll discuss the exceptions below). But even though you're stuck with16-bit resolution with a standard DAT deck, there's still room forimprovement in sound quality.

External high-resolution A/D converters and their proprietarydithering schemes, such as Apogee's UV22 and Sony's Super Bit Mapping,yield results that are superior to those of standard 16-bit converters.Any time you use a higher-resolution converter, you increase yourchances of using the full 16 bits you're allowed on DAT media.

Using outboard converters with a DAT machine is easy. The first stepis to send your analog signal to the converter for translation into ahigh-resolution digital signal. Next, using proprietary circuitry, thedigital word length is dithered to the 16 bits that your DAT canhandle. Finally, this 16-bit digital material is sent to your recordervia a digital cable. This process lets you maximize the number of bitsyou're using in the 16-bit word, resulting in greater resolution andsonic transparency than you would get otherwise.

Hearing the difference that high-resolution converters can make willimmediately open your ears to the world beyond 16 bits. Fortunately,the cost of these converters is dropping while the quality isincreasing. No matter which DAT machine you choose, you'll be able toimprove on the audio quality without having to buy a whole newunit.

SPEED OF SOUND The choices of sampling rates available to theconsumer haven't changed much since the first DAT machines hit themarket. The biggest difference is that you can now easily purchase adeck domestically that records at 44.1 kHz without Serial CopyManagement System (SCMS) encoding (more on that later). Thewidespread-and largely unfounded-fear in the record industry thataverage citizens would use DAT to illegally copy CDs (as well asprerecorded DATs) kept the earliest units from being able to record at44.1 kHz. Thankfully, that nonsense is now history.

For those times when you need more than two hours of record time,many machines have a Long Play mode that allows you to double thattime. In LP mode the tape speed is halved (4.075 mm per second), as isthe head-rotation speed (1,000 rpm); and the word length is reduced to12-bit nonlinear quantization. In addition, LP mode uses a lowersampling rate of 32 kHz-which results in a reduced upper frequencyresponse of 14.5 kHz due to the Nyquist theorem. It is possible in somemachines to record 16-bit words in Standard Play at 32 kHz, although Ihave difficulty imagining a use for this scenario in the personalstudio.

MALLEABLE SUBCODE Each DAT recorder allows the user to write anderase Start, Skip, and End IDs any time after the audio has beenrecorded. That means you can change misaligned IDs as well as eraseerroneous ones: the IDs are part of the subcode; therefore, you neverhave to worry about accidentally erasing part of a song when you editID information.

Because I never know when inspiration will strike (and because tapeis cheap), I always have the DAT rolling when I'm playing. When I'mdone, I listen back and put Start IDs at the points where there ismusic I want to access, and I add Skip IDs at the beginnings ofsections I don't need. Then I press Renumber, and my DAT machinerewinds to the beginning of the tape and renumbers the Start IDssequentially. On a unit like the Fostex D-5, this step also lets youcreate a Table of Contents on the tape so that you can easily accesssongs and timing information.

I also make a habit of adding an End ID when I finish recording forthe day. This way, I can do an End Search and easily pickup where Ileft off.

One thing I take note of immediately is whether a particular DATunit goes directly into Play when I do an ID search from Stop. TheSV-3800 and the DA-45HR, for example, go into Pause in this instance.If you press a search button while these units are playing, theyautomatically go into Play when the correct ID is found. I prefer adeck that goes directly into Play every time I do a search; it saves mefrom having to reach over and push Play as well.

WHEELS OF FIRE Yet another wonderful feature of the DAT machine isthe shuttle wheel. On many machines, this handy device serves doubleduty: its primary function is to shuttle the tape forward andbackward-from one-half to 15 times normal speed, depending on how faryou turn the knob-so you can quickly locate points on the tape by ear.Shuttle wheels are sometimes used for data selection, because they areperfectly suited for scrolling quickly through parameters.

The downside of the shuttle wheel is that it increases the cost ofthe recorder; you can easily save a couple of hundred dollars byeschewing this particular control. If you're looking for a second DATmachine (you do want to make backup copies of your work, don't you?),you can probably get by without a shuttle wheel if your primary deckalready has one. However, I opted for a shuttle wheel on my second deckso that I could use it as a backup if my primary deck was down.

SCMS OF THE UNIVERSE The solution that was adopted to control thenumber of "serial" digital copies allowed is called the Serial CopyManagement System. SCMS controls the number of second-generationdigital copies that can be produced with the IEC-958 Type II "consumer"digital interface format (commonly known as Sony/Philips DigitalInterface Format, or S/PDIF). The setting of ID6 in the tape'ssubcode-not to be confused with Program number ID6-determines whetherserial copying will be allowed.

Although SCMS is still with us, anyone with a pro-quality DATrecorder can relax because AES/EBU digital connections ignore thissubcode information. However, it's good to examine the setup of yourrecorder so that you don't inadvertently put a "copy prohibited" codeonto your tape; you never know when you may need to make a digital dubof your music using a S/PDIF connector, so make sure your recordingsare "copy free."

THE PLAYERS Currently, five manufacturers are distributing DATmachines in the United States-Fostex, HHB, Panasonic, Sony, andTascam-for a total of 15 different models priced between $899 and$3,000. I chose four representative studio models within this range, aswell as a couple of portable units.

Rather than use this section to run through all the features of eachmachine (you can examine the table for that information), I'll focus onspecific features that make each unit unique among the group, as wellas common features that may differ on some units or be missingaltogether.

Fostex D-5. Even though it was the least expensive studio recorderof the group, the D-5 ($1,029) performed as well as any of the units.It has one of the easiest interfaces to navigate (see Fig. 1).Everything you need is on the top level, so you won't find yourselfdescending deep into menus.

The D-5's analog input controls include a single input volume knobthat controls both channels, as well as a center-detented left/rightbalance knob. Although I prefer a separate volume control for eachinput, a single-knob setup is not a problem if you're able to regulateaudio levels before they get to the deck.

The D-5 is also the only studio unit of the bunch that doesn't comewith a shuttle wheel. (However, pressing play and rewind orfast-forward simultaneously allows you to scan the audio in a similarway.)

One feature I found quite useful on the D-5 is that you can create aTable of Contents (TOC) in the subcode of a tape. The TOC lists thenumber of IDs on the tape, the total time of the recorded portion ofthe tape, the length of each piece identified by an ID, and the starttime of each piece. This is a handy feature if you're sharing tapeswith people who have the capability of reading TOC material.

Immediate access to all the basic features is at your fingertips onthe front panel, including the choice of 48, 44.1, and 32 kHz (LP)sampling frequencies. But many of the buttons are tiny, such as the IDsearch buttons, Counter Mode and Reset, Renumber, and Wireless Off(which turns off the receiver for the wireless remote control).Fortunately, the buttons have enough space between them that you won'taccidentally push two at the same time.

The only thing I found inconvenient on the D-5 was using the MarginReset. The Margin is a common feature of DAT machines that gives you areading of the input level in decibels. On the D-5, the display for theMargin numbers shares the same characters as the program ID numbers.Unfortunately, you can't just press the Margin Reset button to get areading; you have to hold it down, because the display goes back to theprogram number when the button is released. I use the Margin reading toset record levels with a DAT deck, and keeping a finger on the MarginReset button while adjusting levels can be a nuisance.

Like the front panel, the rear panel of the D-5 is a model ofsimplicity: XLR inputs and outputs for analog connection, and AES/EBUand optical digital I/O. Analog I/O level (-10 or +4) is designatedusing a back panel switch. (You select the type of digital I/O you wantto use from the front panel.) There is also a 5-pin DIN plug thataccepts a parallel remote (GPI) input connector, though the suppliedwireless remote works just fine.

Sony PCM-R500. The PCM-R500 ($1,695), Sony's midprice studio DATrecorder, fell within our price range and features a motor transportwith four direct drives (see Fig. 2). The R300 ($995) is similar inmany ways to the R500 but doesn't include a shuttle wheel, while theR700 has everything the R500 has and more. In fact, the latter twomodels are so closely matched that they share a manual.

The R500's shuttle wheel is actually two controllers in one. Theinner dial is a data wheel that lets you specify parameters as you makeadjustments in the menus. The outer dial performs regular shuttleduties with audio, but it also selects the menu you want to edit indata mode. Once I got used to this setup, I found it a convenient wayto work.

The R500 also adds a time stamp to your recordings: once you set thedate, day of the week, and time, the unit will put this informationinto the subcode of the tape every time you record. This, of course,gives you the ability to identify a tape that is otherwise unlabled. Ionly wish that this feature were standard on every DAT machine.

The best news about the Sony studio DAT decks is that they includethe company's Super Bit Mapping (SBM) technology. SBM, which is engagedor defeated using a front-panel switch, converts the analog signal to20 bits; then it reduces the word length to 16 bits when recording totape, using a proprietary noise-shaping algorithm. You're not using anysort of encoding/decoding scheme, so recordings made with SBM can beplayed on any other DAT machine without losing the increasedresolution. SBM is used only when recording analog sources. It comesstandard on the R500, making this unit a great value for the money.

Like the D-5, the PCM-R500 has a handy "wireless off" feature andcan play and record all three sampling rates, including 32 kHz LongPlay. But the R500 also lets you vary the length of Start IDs;djust thethreshold for automatic ID writing (ranging from -12 to -60 dB, in 1 dBunits); and adjust the amount of time that a low-level signal must play(from 1 to 10 seconds in 1-second intervals) before an ID isautomatically written.

One thing I miss on the R500 is programmable playback. It has none.Nevertheless, the R500 makes great-sounding recordings, with or withoutSuper Bit Mapping. I left SBM on all the time because I couldn't comeup with a reason to leave it off.

Panasonic SV-3800. To my eyes, the front-panel layout of Panasonic'sSV-3800 ($1,695) is the most logically arranged of the bunch (see Fig.3). The features I need most when working are all on the front panel,including the A/D input selector, End Search button, and fade buttons.The shuttle wheel lets you search up to 15 times the normal tapespeed-almost twice as fast as the other decks in this survey. It's alsothe only studio deck that doesn't have built-in rack ears (although theparts are supplied with the unit).

The nominal output of the SV-3800 is incrementally variable over an11 dB range from +4 dB to -6 dB, then directly to -10 dB. And like theR500, it lets you monitor an audio input without a tape in the drive.The SV-3800 doesn't, however, read 32 kHz material, in either Standardor Long Play mode.

One of the things that sets the SV-3800 apart from the pack is thatit can interface in three digital I/O types: AES/EBU (XLR), S/PDIFcoaxial, and S/PDIF optical. To switch among them you have to descend alevel or two into the menus. But that's okay, because it also gives youa chance to select what kind of digital signal is sent out over each ofthe digital connectors. For example, on the digital XLR connectors youcan select either standard AES/EBU or the consumer-oriented IEC-958Type II format (which usually comes over optical or coaxial jacks).This feature gives the SV-3800 an even greater degree ofdigital-dubbing flexibility.

Thankfully, the rear-panel DIP switches that were part of theSV-3700 are gone from the SV-3800, and their functions are now embeddedin the menus. This means that you can change the SCMS/ID6 status ordigital I/O format without having to go behind the unit to do it.

The next step up in a Panasonic DAT player is the pro-orientedSV-4100 ($2,650). It comes with a buffer memory and can lock to wordclock and blackburst.

Tascam DA-45HR. Although Tascam has two studio DAT models that areless expensive (the DA-20 MKII at $975 and the DA-40 at $1,399), Ichose to look at the DA-45HR ($2,165) because it can record in both 24and 16 bits (see Fig. 4). The unit records at double-speed to get the24-bit word length onto tape-which means your maximum record time isone hour in High Resolution mode. In 16-bit Standard Play mode, itoperates as you would expect. The DA-45HR, however, lacks an LP modeand it is the only studio DAT player I used that doesn't come with awireless remote control. You'll need to spring for the RC-D45 remote($99) if you want to work with this deck from a distance.

In sound quality, the 16-bit recordings made on the DA-45HRsurpassed those of other 16-bit units, primarily because the DA-45HRuses a 24-bit A/D converter and rounds down to 16 bits. I was able toimprove on the sound even further by using an Apogee PSX-100 with UV22.(Designed in part to let you create a DAT backup, the PSX-100 can make24-bit and 16-bit recordings simultaneously, which was very helpful inthis particular reviewing situation.)

In HR mode, the DA-45HR's 24-bit recordings sounded far superior tothe 16-bit tracks made with the same recorder. The 16-bit recordingsseemed harsher, while the HR tracks had an improved dynamic range andan evenly distributed frequency range. Even with the deck's 20-bit D/Aconverters, the greater resolution was apparent.

The DA-45HR lets you title each program ID with up to 60 charactersfor viewing in the display. You create the titles, which are added tothe subcode, by using the unit's data/shuttle wheels to choosealphanumeric characters. Because the titles are written into thesubcode, they do not affect the audio portion of the tape, no matterwhich machine you use for playback. The feature also allows you to cutand paste characters from one title to the next, which is convenientwhen you're doing mixes of the same piece. Note that these titles (aswell as 24-bit recordings) can be read only on a DA-45HR; they won't beof any use if you play the tape in another model of DAT player. (Forfurther details on the DA45-HR, see the Quick Pick review in the August1999 issue of EM.)

IN THE FIELD For many recordists, the ability to make high-qualityrecordings outside of the studio is one of the biggest draws of DATtechnology. For these people, the state of the portable DAT recorderhas never been better.

The big difference between the portables and the studio machines isthat the portables include mic preamps and sometimes phantom power aswell. The mic inputs range from 11/48-inch miniplugs to XLR jacks onthe more expensive models. The quality of the preamps and connectionskeeps getting better, and the durability of the units is alsoincreasing.

One important thing to consider in a portable is its battery time.When you combine mic preamps, phantom power, a headphone amp, and theregular mechanics of recording and playback, you can see why batterylife is a major issue with portable units. (See "Gear to Go" in theNovember 1997 issue of EM for more on field-recording accessories.) Butthe manufacturers are on the case: the most recent portable decks usebattery power a lot more wisely than previous models did.

With these issues in mind, let's look at three popular DATportables.

Sony PCM-M1. The latest in a line of highly popular, low-costportable DAT recorders from Sony, the PCM-M1 ($1,000; see Fig. 5)includes a number of key improvements over Sony's lowest-pricedportable, the D8 ($899). The main differences between the two units isthat the M1 takes fewer batteries (two), has a longer playing timeusing rechargeable batteries supplied with the unit (three hours and 45minutes), allows you to defeat SCMS, and has improved mic preamps. ThePCM-M1, unlike the D8, comes with an AC adapter.

The Walkman-style interface of the M1 helps you get up and runningvery quickly. The various buttons and switches are easy to understand.However, because they're scattered around the body of the recorder,accessing some of them is difficult when the unit is inside itsprotective case.

The M1 sounds better and is easier to operate than earlier Sonyportables. To further improve the M1's sound and interfacingcapabilities, Sony sells the SBM-1 Super Bit Mapping attachment ($550),which not only gives you the increased sound quality of 20-bit A/Dconverters but also includes a pair of 11/44-inch inputs, a pair of RCAinputs, a 3.5 mm stereo miniconnector for line input and headphoneoutput, independent level adjustment for the two channels, and even a20 dB mic pad. The price of the SBM-1 attachment may seem a littlesteep at first, but keep in mind that it gives you both increaseddigital resolution and pro connectors-all in a unit that's roughly thesame size as the M1 itself.

Interestingly, the M1 doesn't have a power switch. Also, it wouldn'tlet me exercise a blank tape before recording (even though the manualsuggested doing this). Exercising the tape is an important step: youfast-forward to the end of the tape and then rewind to the beginning.This helps the tape wind evenly throughout and removes any extraneouselements that are clinging to it. Unfortunately, because the M1wouldn't allow it, I had to use the Sony PCM-R500 for this task.

Tascam DA-P1. Yes, it does cost twice as much as the PCM-M1, butTascam's DA-P1 ($2,060) is a fully professional unit that could just aseasily serve as a studio DAT machine when you're not in the field. TheDA-P1 has a pair of balanced XLR mic/line inputs, phantom power, RCAjacks for line-level analog I/O, SCMS-free coaxial digital I/O, andseparate level controls for each analog input channel. The unit comeswith all of the ID functions you would expect from a pro DAT deck.

The DA-P1 also includes a Hold switch; once you're in Record or Playmode, use Hold to disable the other controls so that you won'taccidentally stop the machine or change a setting. You can alsoilluminate the display, though only for 10-second intervals; that meansyou will be hitting the display button over and over again when settinglevels in the dark.

That point aside, I've used several DA-P1 units over the years forvarious projects and have never been disappointed by their sound orfunction. (For more information on the DA-P1, see the review in theJuly 1997 issue of EM.)

HHB PDR1000. The next step up in price takes us to the HHB PDR1000($2,995; see Fig. 6). The unit I received was actually the fully loadedtime-code model known as the PDR1000/TC Plus ($6,995). On its own,however, the PDR1000 comes suited up with a soft case, an RB110dual-bay battery recharger (which also serves as the AC power supply),and an MHB220 nickel-metal-hydride battery. This particular battery ispurported to show fewer signs of "memory effect" trouble thannickel-cadmium rechargeable batteries. To extend the battery life, therecharger has a handy "refresh" feature that completely discharges thebattery before recharging it.

What's remarkable about the PDR1000 is that it's so light (4.3pounds), even with the addition of the time-code unit. And I reallyappreciate the design of the carrying case, which allows easy access tothe sides of the unit (where connections are made) as well as to thetop and front.

The PDR1000 features that I was most thrilled about include a4-head/4-motor transport, a pair of balanced XLR mic/+4 dB line inputs,a built-in speaker for field monitoring, and the ability to read andrecord in 32 kHz/LP or 32 kHz/SP modes. Because the PDR1000 has fourheads, you can monitor either the source or the tape. The unit can alsoadd a time stamp to the subcode of a tape for identification.

The PDR1000 allows you to lock the input-level controls once youhave set them. In addition, a separate Key Hold button disables all ofthe controls that could potentially disrupt a recording, so you canfurther secure your player in a field-recording situation.

The mic preamps sound very good and were perhaps a little hotterthan those of the other portable units I used. The recording experiencewas further enhanced by the HM1000 ($350), a 5-position mid-sideheadphone matrix switch that allowed me to choose among severalheadphone monitoring settings: stereo, mono left, mono right, M-Sstereo, and mono sum. The headphone matrix (which does not comestandard but is essential for the serious concert recordist), combinedwith an AKG C 426 stereo mic, enabled me to dial in the perfectstereo-mic setting, since I could switch between monitoring the stereospread, the sound of the individual channels, and the overall monocompatibility.

DAT'S ALL, FOLKS Whether it's a stereo recorder or a mastering ormixdown device you need, DAT is still a strong option, and one thatwill be with us for some time to come. After 12 years of service, ithas shown itself to be a rugged, durable technology with a lot offlexibility. Even within DAT's 16-bit limit, you can now get betterresults than ever before with the advent of affordable outboard digitalconverters.

Gino Robair, an associate editor at EM, formally apologizes for allthe puns on the DAT acronym. Special thanks to AKG and Whirlwind/USAudio.

If you've been around the computer industry at all, you know thatDAT tape is also used as a back-up storage medium for data other thandigital audio. Although both kinds of machines use digital tape,data-storage machines and tapes are substantially different in designthan those made for recording audio. Many engineers I know won't usedata-backup tapes for audio production due to the increased risk ofdropouts and other problems.

These cassettes are often referred to as Data DATs, and they come inlengths that can yield up to 180 minutes of recording time. This makesthem attractive to engineers needing three hours of recording time.However, manufacturers of audio DAT equipment recommend against usingtapes that play longer than 120 minutes, and I'm going to recommendagainst using Data DAT tapes in general for music. To see why, we needto look closely at how DAT tapes are made, including the tape and theshell.

Like analog tape, digital audio tape has a magnetic coating that isattached to a plastic backing using an adhesive binder. Meter-widesheets of this tape are manufactured and cut down into strips that are4 millimeters in width for use in DAT cassettes. The most consistentlayer of magnetic coating happens to be in the center of these largesheets, and this is the portion that is used for high-quality tape,especially for Data tapes. In addition, tape stocks come in differentthicknesses, and that's where we begin to get into trouble.

The biggest problem with 180-minute tapes is that they are a thinnerstock than that which is in tapes of up to 120 minutes, since there'sonly so much room inside a cassette shell. Audio DAT decks areoptimized for a specific thickness and tension that shouldn't exceedthat found in the 120-minute variety.

According to some manufacturers, one of the biggest reasons thatData DAT tapes don't particularly work well in audio decks has to dowith the cassette housing or shell. Data DATs use a different, lessexpensive housing (which effects tension and tape movement) that isn'tup to the standards that audio DAT machines require. Data machines andtapes have a wider tolerance for movement within the cassette thanaudio DATs-a tolerance that is beyond what audio recorders can safelyhandle. The cheaper shells can cause the tape to not trackproperly.

The common misconception is that tape formulation alone determinesDAT-tape quality. However, it's the total package-tape and shell-thatdetermines the ultimate stability of the DAT media.