What's Up with DAT?

Nov 1, 1999 12:00 PM, Gino Robair

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 to its full potential: DAT.

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

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

WHERE DID DAT COME FROM? In 1987, the year DAT machines began to appear at industry trade shows, home recording was much different than it is today. The Amiga, Atari, and Macintosh computers were au courant for electronic music, the cassette multitrack recorder was king, and most people didn't have a .com address on their business cards.

The choices for an affordable 2-track mastering deck were also different. Besides analog reel-to-reel and cassette formats, there was Beta and VHS Hi-Fi, as well as the Sony PCM-F1 digital format. With the less expensive analog formats, you had to use noise reduction to get optimal sound; with VCRs, you were stuck with an unpleasant compression/expansion noise-reduction scheme that the user couldn't disable; and PCM-F1 was sometimes unreliable and sonically not too desirable.

AND ALONG CAME DAT DAT machines combine a couple of technologies familiar to our circa-1987 home recordist-the videocassette recorder (VCR) and a pulse-code modulation (PCM) processor. DAT machines store digital information on tape via helical scanning using a miniaturized rotating head. This technology was originally called Rotary-head DAT, or R-DAT for short. (Also in development at the time, though never commercially released, was a system called Stationary-head DAT, or S-DAT.)

Although DAT was originally intended as a consumer-oriented digital replacement of the ubiquitous Philips analog cassette tape, its success was nipped in the bud primarily because it could be used to be make direct digital copies of compact discs. The U.S. recording industry, with the help of Congress, immediately sued Sony to prohibit sales of DAT gear in the United States and lobbied hard for a copy-protection scheme. The result was that individuals who wanted an early DAT machine had to acquire a nit through the gray market if they wanted to avoid the copy-protection circuitry. This, of course, meant that you'd have to take your machine to Japan or Europe if it needed servicing-not very practical 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 the user to defeat the copy protection. Today DAT is still the most common 2-track recording medium used by pros, not to mention the legions of music fans that occupy the "taping section" at rock concerts.

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

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

For starters, digital audio tape has proven to be a robust, yet inexpensive and compact, medium for storing sound. Thanks to the popularity of the DTRS (which uses Hi-8 video cassettes) and ADAT formats, tape will be with us for a while longer-especially those of us with huge DAT, ADAT, and DTRS archives. And in the age of hard-disk recording and CD-RW, the mighty DAT machine still offers features that are unavailable in any other format: up to two hours of full-frequency digital audio without compression; high-quality, low-cost reusable media; and compatibility and portability (every 16-bit, 44.1 kHz digital audio tape can play in any DAT machine, including the portable ones).

LENGTH IS EVERYTHING With DAT you can record up to two uninterrupted hours of music, at a higher resolution than the average CD. If you want to 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 determining factor in your choice of a DAT deck.

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

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

As with other gear, the overall design of the DAT machine's user interface determines the way the product can be used. For example, if a particularly useful feature is embedded deep in the menus, it's unlikely that the feature will get much use. Therefore, it's important to know which features you will need in a DAT deck before you go shopping for one.

THE RESOLUTION ENVELOPE One factor that will determine the "sound" of a particular digital recorder are its A/D converters. Most of the units I tested for this article have comparable-sounding converters (I'll discuss the exceptions below). But even though you're stuck with 16-bit resolution with a standard DAT deck, there's still room for improvement in sound quality.

External high-resolution A/D converters and their proprietary dithering 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 your chances of using the full 16 bits you're allowed on DAT media.

Using outboard converters with a DAT machine is easy. The first step is to send your analog signal to the converter for translation into a high-resolution digital signal. Next, using proprietary circuitry, the digital word length is dithered to the 16 bits that your DAT can handle. Finally, this 16-bit digital material is sent to your recorder via a digital cable. This process lets you maximize the number of bits you're using in the 16-bit word, resulting in greater resolution and sonic transparency than you would get otherwise.

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

SPEED OF SOUND The choices of sampling rates available to the consumer haven't changed much since the first DAT machines hit the market. The biggest difference is that you can now easily purchase a deck domestically that records at 44.1 kHz without Serial Copy Management System (SCMS) encoding (more on that later). The widespread-and largely unfounded-fear in the record industry that average citizens would use DAT to illegally copy CDs (as well as prerecorded DATs) kept the earliest units from being able to record at 44.1 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 that time. In LP mode the tape speed is halved (4.075 mm per second), as is the head-rotation speed (1,000 rpm); and the word length is reduced to 12-bit nonlinear quantization. In addition, LP mode uses a lower sampling rate of 32 kHz-which results in a reduced upper frequency response of 14.5 kHz due to the Nyquist theorem. It is possible in some machines to record 16-bit words in Standard Play at 32 kHz, although I have difficulty imagining a use for this scenario in the personal studio.

MALLEABLE SUBCODE Each DAT recorder allows the user to write and erase Start, Skip, and End IDs any time after the audio has been recorded. That means you can change misaligned IDs as well as erase erroneous ones: the IDs are part of the subcode; therefore, you never have to worry about accidentally erasing part of a song when you edit ID information.

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

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

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

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

The downside of the shuttle wheel is that it increases the cost of the recorder; you can easily save a couple of hundred dollars by eschewing this particular control. If you're looking for a second DAT machine (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 deck already has one. However, I opted for a shuttle wheel on my second deck so 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 the number of "serial" digital copies allowed is called the Serial Copy Management System. SCMS controls the number of second-generation digital copies that can be produced with the IEC-958 Type II "consumer" digital interface format (commonly known as Sony/Philips Digital Interface Format, or S/PDIF). The setting of ID6 in the tape's subcode-not to be confused with Program number ID6-determines whether serial copying will be allowed.

Although SCMS is still with us, anyone with a pro-quality DAT recorder can relax because AES/EBU digital connections ignore this subcode information. However, it's good to examine the setup of your recorder so that you don't inadvertently put a "copy prohibited" code onto your tape; you never know when you may need to make a digital dub of your music using a S/PDIF connector, so make sure your recordings are "copy free."

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

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

Fostex D-5. Even though it was the least expensive studio recorder of 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 yourself descending deep into menus.

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

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

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

Immediate access to all the basic features is at your fingertips on the 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 ID search 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't accidentally push two at the same time.

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

Like the front panel, the rear panel of the D-5 is a model of simplicity: XLR inputs and outputs for analog connection, and AES/EBU and optical digital I/O. Analog I/O level (-10 or +4) is designated using a back panel switch. (You select the type of digital I/O you want to use from the front panel.) There is also a 5-pin DIN plug that accepts a parallel remote (GPI) input connector, though the supplied wireless remote works just fine.

Sony PCM-R500. The PCM-R500 ($1,695), Sony's midprice studio DAT recorder, fell within our price range and features a motor transport with four direct drives (see Fig. 2). The R300 ($995) is similar in many ways to the R500 but doesn't include a shuttle wheel, while the R700 has everything the R500 has and more. In fact, the latter two models are so closely matched that they share a manual.

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

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

The best news about the Sony studio DAT decks is that they include the company's Super Bit Mapping (SBM) technology. SBM, which is engaged or defeated using a front-panel switch, converts the analog signal to 20 bits; then it reduces the word length to 16 bits when recording to tape, using a proprietary noise-shaping algorithm. You're not using any sort of encoding/decoding scheme, so recordings made with SBM can be played on any other DAT machine without losing the increased resolution. SBM is used only when recording analog sources. It comes standard 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 and can play and record all three sampling rates, including 32 kHz Long Play. But the R500 also lets you vary the length of Start IDs;djust the threshold for automatic ID writing (ranging from -12 to -60 dB, in 1 dB units); 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 is automatically written.

One thing I miss on the R500 is programmable playback. It has none. Nevertheless, the R500 makes great-sounding recordings, with or without Super Bit Mapping. I left SBM on all the time because I couldn't come up with a reason to leave it off.

Panasonic SV-3800. To my eyes, the front-panel layout of Panasonic's SV-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 tape speed-almost twice as fast as the other decks in this survey. It's also the only studio deck that doesn't have built-in rack ears (although the parts are supplied with the unit).

The nominal output of the SV-3800 is incrementally variable over an 11 dB range from +4 dB to -6 dB, then directly to -10 dB. And like the R500, 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 Standard or Long Play mode.

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

Thankfully, the rear-panel DIP switches that were part of the SV-3700 are gone from the SV-3800, and their functions are now embedded in the menus. This means that you can change the SCMS/ID6 status or digital 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-oriented SV-4100 ($2,650). It comes with a buffer memory and can lock to word clock and blackburst.

Tascam DA-45HR. Although Tascam has two studio DAT models that are less expensive (the DA-20 MKII at $975 and the DA-40 at $1,399), I chose to look at the DA-45HR ($2,165) because it can record in both 24 and 16 bits (see Fig. 4). The unit records at double-speed to get the 24-bit word length onto tape-which means your maximum record time is one hour in High Resolution mode. In 16-bit Standard Play mode, it operates as you would expect. The DA-45HR, however, lacks an LP mode and it is the only studio DAT player I used that doesn't come with a wireless 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-45HR surpassed those of other 16-bit units, primarily because the DA-45HR uses a 24-bit A/D converter and rounds down to 16 bits. I was able to improve 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 make 24-bit and 16-bit recordings simultaneously, which was very helpful in this particular reviewing situation.)

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

The DA-45HR lets you title each program ID with up to 60 characters for viewing in the display. You create the titles, which are added to the subcode, by using the unit's data/shuttle wheels to choose alphanumeric characters. Because the titles are written into the subcode, they do not affect the audio portion of the tape, no matter which machine you use for playback. The feature also allows you to cut and paste characters from one title to the next, which is convenient when you're doing mixes of the same piece. Note that these titles (as well as 24-bit recordings) can be read only on a DA-45HR; they won't be of any use if you play the tape in another model of DAT player. (For further details on the DA45-HR, see the Quick Pick review in the August 1999 issue of EM.)

IN THE FIELD For many recordists, the ability to make high-quality recordings outside of the studio is one of the biggest draws of DAT technology. For these people, the state of the portable DAT recorder has never been better.

The big difference between the portables and the studio machines is that the portables include mic preamps and sometimes phantom power as well. The mic inputs range from 11/48-inch miniplugs to XLR jacks on the more expensive models. The quality of the preamps and connections keeps getting better, and the durability of the units is also increasing.

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

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

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

The Walkman-style interface of the M1 helps you get up and running very 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 its protective case.

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

Interestingly, the M1 doesn't have a power switch. Also, it wouldn't let me exercise a blank tape before recording (even though the manual suggested doing this). Exercising the tape is an important step: you fast-forward to the end of the tape and then rewind to the beginning. This helps the tape wind evenly throughout and removes any extraneous elements that are clinging to it. Unfortunately, because the M1 wouldn'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, but Tascam's DA-P1 ($2,060) is a fully professional unit that could just as easily serve as a studio DAT machine when you're not in the field. The DA-P1 has a pair of balanced XLR mic/line inputs, phantom power, RCA jacks for line-level analog I/O, SCMS-free coaxial digital I/O, and separate level controls for each analog input channel. The unit comes with 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 Play mode, use Hold to disable the other controls so that you won't accidentally stop the machine or change a setting. You can also illuminate the display, though only for 10-second intervals; that means you will be hitting the display button over and over again when setting levels in the dark.

That point aside, I've used several DA-P1 units over the years for various projects and have never been disappointed by their sound or function. (For more information on the DA-P1, see the review in the July 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 loaded time-code model known as the PDR1000/TC Plus ($6,995). On its own, however, the PDR1000 comes suited up with a soft case, an RB110 dual-bay battery recharger (which also serves as the AC power supply), and an MHB220 nickel-metal-hydride battery. This particular battery is purported to show fewer signs of "memory effect" trouble than nickel-cadmium rechargeable batteries. To extend the battery life, the recharger has a handy "refresh" feature that completely discharges the battery before recharging it.

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

The PDR1000 features that I was most thrilled about include a 4-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 and record in 32 kHz/LP or 32 kHz/SP modes. Because the PDR1000 has four heads, you can monitor either the source or the tape. The unit can also add a time stamp to the subcode of a tape for identification.

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

The mic preamps sound very good and were perhaps a little hotter than those of the other portable units I used. The recording experience was further enhanced by the HM1000 ($350), a 5-position mid-side headphone matrix switch that allowed me to choose among several headphone monitoring settings: stereo, mono left, mono right, M-S stereo, and mono sum. The headphone matrix (which does not come standard but is essential for the serious concert recordist), combined with an AKG C 426 stereo mic, enabled me to dial in the perfect stereo-mic setting, since I could switch between monitoring the stereo spread, the sound of the individual channels, and the overall mono compatibility.

DAT'S ALL, FOLKS Whether it's a stereo recorder or a mastering or mixdown device you need, DAT is still a strong option, and one that will be with us for some time to come. After 12 years of service, it has shown itself to be a rugged, durable technology with a lot of flexibility. Even within DAT's 16-bit limit, you can now get better results than ever before with the advent of affordable outboard digital converters.

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

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

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

Like analog tape, digital audio tape has a magnetic coating that is attached to a plastic backing using an adhesive binder. Meter-wide sheets of this tape are manufactured and cut down into strips that are 4 millimeters in width for use in DAT cassettes. The most consistent layer of magnetic coating happens to be in the center of these large sheets, and this is the portion that is used for high-quality tape, especially for Data tapes. In addition, tape stocks come in different thicknesses, and that's where we begin to get into trouble.

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

According to some manufacturers, one of the biggest reasons that Data DAT tapes don't particularly work well in audio decks has to do with the cassette housing or shell. Data DATs use a different, less expensive housing (which effects tension and tape movement) that isn't up to the standards that audio DAT machines require. Data machines and tapes have a wider tolerance for movement within the cassette than audio DATs-a tolerance that is beyond what audio recorders can safely handle. The cheaper shells can cause the tape to not track properly.

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