Digital Audio Tape (DAT orR-DAT) is a signal recording and playback medium developed bySony and introduced in 1987.^[1] In appearance it is similar to aCompact Cassette, using 3.81 mm / 0.15" (commonly referred to as 4 mm)magnetic tape enclosed in a protective shell, but is roughly half the size at 73 mm × 54 mm × 10.5 mm. The recording isdigital rather thananalog. DAT can record at sampling rates equal to, as well as higher and lower than aCD (44.1, 48, or 32kHzsampling rate respectively) at 16bitsquantization. If a comparable digital source is copied without returning to the analogue domain, then the DAT will produce an exact clone, unlike other digital media such asDigital Compact Cassette or non-Hi-MD MiniDisc, both of which use a lossy data-reduction system.

Digital Audio Tape

A 90-minute DAT cartridge, with aAAA battery (LR03) for size comparison
Media type	Magnetic cassette tape
Encoding	Lossless real-time
Capacity	Up to 120 or 180 minutes (consumer tapes on non-LP mode)
Read mechanism	Rotating head, helical scan
Write mechanism	Rotating head, helical scan
Developed by	Sony
Usage	Audio storage
Extended to	Digital Data Storage
Released	1987; 38 years ago (1987)

Like most formats ofvideocassette, a DAT cassette may only be recorded and played in one direction, unlike an analogcompact audio cassette, although many DAT recorders had the capability to record program numbers and IDs, which can be used to select an individual track like on a CD player.

Although intended as a replacement for analog audio compact cassettes, the format was never widely adopted by consumers because of its expense, as well as concerns from the music industry about unauthorized high-quality copies. The format saw moderate success in professional markets and as a computer storage medium, which was developed into theDigital Data Storage format. As Sony has ceased production of new recorders, it will become more difficult to play archived recordings in this format unless they are copied to other formats or hard drives. Meanwhile, the phenomenon ofsticky-shed syndrome has been noted by some engineers involved in re-mastering archival recordings on DAT, which presents a further threat to audio held exclusively in this medium.

The technology of DAT is closely based onvideo recorders, using a rotating head andhelical scan to record data. This prevents DATs from being physicallyedited in the cut-and-splice manner ofanalog tapes, or open-reel digital tapes likeProDigi orDASH. In 1983, a DAT meeting was established to unify the standards for recording digital audio on magnetic tape developed by each company and in 1985, two standards were created:R-DAT (Rotating Digital Audio Tape) using a rotary head andS-DAT (Stationary Digital Audio Tape) using a fixed head. The S-DAT format had a simple mechanism similar to theCompact Cassette format but was difficult to develop a fixed recording head for high-density recording while the rotating head of the R-DAT had a proven track record in VCR formats likeVHS &Betamax. As the S-DAT version was never released, R-DAT had been renamed as simply "DAT" by the time of its launch. However, Philips and Matsushita (Panasonic) would later release their own stationary head digital format in the form of theDigital Compact Cassette. Sony would later introduce another rotating head format in the form ofNT which was intended to replace theMicrocassette andMini-Cassette.^{[citation needed]}

The DAT standard allows for four sampling modes: 32 kHz at 12 bits, and 32 kHz, 44.1 kHz or 48 kHz at 16 bits. Certain recorders operate outside the specification, allowing recording at 96 kHz and 24 bits (HHS). Some early machines aimed at the consumer market did not operate at 44.1 kHz when recording so they could not be used to 'clone' a compact disc. Since each recording standard uses the same tape, the quality of the sampling has a direct relation to the duration of the recording – 32 kHz at 12 bits will allow six hours of recording onto a three-hour tape while HHS will only give 90 minutes from the same tape. Included in the signal data are subcodes to indicate the start and end of tracks or to skip a section entirely; this allows for indexing and fast seeking. Two-channelstereo recording is supported under allsampling rates and bit depths, but the R-DAT standard does support 4-channel recording at 32 kHz.^{[citation needed]}

DATs are between 15 and 180 minutes in length, a 120-minute tape being 60 metres in length. DATs longer than 60 metres tend to be problematic in DAT recorders due to the thinner media. DAT machines running at 48 kHz and 44.1 kHz sample rates transport the tape at 8.15 mm/s. DAT machines running at 32 kHz sample rate transport the tape at 4.075 mm/s.^{[citation needed]}

DAT was not the first digital audio tape;pulse-code modulation (PCM) was used inJapan byDenon in 1972 for the mastering and production of analoguephonograph records, using a2-inch Quadruplex-format videotape recorder for itstransport, but this was not developed into aconsumer product. Denon's development dated from its work with Japan's NHK Broadcasting; NHK developed the first high-fidelity PCM audio recorder in the late 1960s. Denon continued development of their PCM recorders that used professional video machines as the storage medium, eventually building 8-track units used for, among other productions, a series of jazz records made in New York in the late 1970s.^{[citation needed]}

In 1976, another digital audio tape format was developed bySoundstream, using one inch (25.4 mm) widereel-to-reel tape loaded on aninstrumentation recorder manufactured byHoneywell acting as a transport, which in turn was connected to outboard digital audio encoding and decoding hardware of Soundstream's own design. Soundstream's format was improved through several prototypes and when it was developed to 50 kHz sampling rate at 16 bits, it was deemed good enough for professional classical recording by the company's first client,Telarc Records of Cleveland, Ohio. Telarc's April, 1978 recording of the Holst Suites for Band byFrederick Fennell and the Cleveland Wind Ensemble was a landmark release, and ushered indigital recording for America's classical music labels. Soundstream's system was also used byRCA.^{[citation needed]}

Starting in 1978,3M introduced its own line and format of digital audio tape recorders for use in arecording studio. One of the first prototypes of 3M's system was installed in the studios ofSound 80 inMinneapolis, Minnesota. This system was used in June 1978 to recordAaron Copland's "Appalachian Spring" by the St. Paul Chamber Orchestra conducted by Dennis Russell Davies. That record was the first Grammy-winning digital recording. The production version of the 3M Digital Mastering System was used in 1979 to record the first all-digital rock album,Ry Cooder's "Bop Till You Drop," made at Warner Brothers Studio in California.^{[citation needed]}

The first consumer-oriented PCM format used consumer video tape formats (Beta and VHS) as the storage medium. These systems used the EIAJ digital format, which sampled at 44.056 kHz at 14 bits. The Sony PCM-F1 system debuted in 1981, and Sony from the start offered the option of 16-bit wordlength. Other systems were marketed by Akai, JVC, Nakamichi and others. Panasonic, via its Technics division, briefly sold a digital recorder that combined an EIAJ digital adapter with a VHS video transport, the SV-P100. These machines were marketed by consumer electronics companies to consumers, but they were very pricey compared to cassette or even reel-to-reel decks of the time. They did catch on with the more budget conscious professional recordists, and some boutique-label professional releases were recorded using these machines.^[2]

Starting in the early 1980s, professional systems using aPCM adaptor were also common as mastering formats. These systems digitized an analog audio signal and then encoded the resulting digital stream into an analog video signal so that a conventional VCR could be used as a storage medium.^{[citation needed]}

One of the most significant examples of a PCM adaptor-based system was theSony PCM-1600 digital audio mastering system, introduced in 1978. The PCM-1600 used aU-Matic-format VCR for its transport, connected to external digital audio processing hardware. It (and its later versions such as the PCM-1610 and 1630) was widely used for the production and mastering of some of the first Digital Audio CDs in the early 1980s. Once CDs were commercially introduced in 1982, tapes recorded on the PCM-1600 were sent to the CD pressing plants to be used to make the glass master disc for CD replication.^{[citation needed]}

Other examples includedbx, Inc.'sModel 700 system, which, similar to laterSuper Audio CDs, used a high sample-rate delta-sigma modulation rather than PCM; Decca's 1970sPCM system,^[3] which used a videotape recorder manufactured byIVC for a transport; andMitsubishi's X-80 digital recorder, a 6.4 mm (1⁄4 in)open reel digitalmastering format that used a very unusual sampling rate of 50.4 kHz.^{[citation needed]}

For high-quality studio recording, all of these formats were effectively made obsolete in the early 1980s by two competingreel-to-reel formats with stationary heads:Sony'sDASH format andMitsubishi's continuation of the X-80 recorder, which was improved upon to become theProDigi format. (In fact, one of the first ProDigi-format recorders, the Mitsubishi X-86C, was playback-compatible with tapes recorded on an X-80.) Both of these formats remained popular as an analog alternative until the early 1990s, when hard disk recorders rendered them obsolete.^{[citation needed]}

Sony released its last DAT product with the DAT Walkman TCD-D100 in 1995 and continued to produce it until November 2005 when Sony announced that its remaining DAT machine models would be discontinued the following month.^[4] Sony had sold around 660,000 DAT products since its introduction in 1987.^{[citation needed]} Sony continued to produce blank DAT tapes until 2015 when it announced it would cease production by the end of the year. Even with this, the DAT format still finds regular use infilm andtelevision recording,^{[citation needed]} primarily due to the support in some recorders forSMPTE time code synchronisation, and sometimes by audio enthusiasts as a way of backing up vinyl, compact cassette and CD collections to a digital format to then be transferred to PC. Although it has been superseded by modernhard disk recording ormemory card equipment, which offers much more flexibility and storage,Digital Data Storage tapes, which are broadly similar to DATs, apart from tape length and thickness on some variants, and are still manufactured today unlike DAT cassettes, are often used as substitutes in many situations.^{[citation needed]}

The DAT recorder mechanism was considerably more complex and expensive than an analoguecassette deck mechanism due to the rotary helical scan head, thereforePhilips andPanasonic Corporation developed a rivaldigitaltape recorder system with a stationary head based on theanaloguecompact cassette known as S-DAT. TheDigital Compact Cassette (DCC) was cheaper and simpler mechanically than DAT, but did not make perfect digital copies as it used alossy compression technique calledPASC. (Lossy compression was necessary to reduce the data rate to a level that the DCC head could record successfully at the linear tape speed of 4.75 cm/s that the compact cassette system uses.) DCC was never a competitor to DAT in recording studios, because DAT was already established, and studios favor lossless formats. As DCC was launched at the same time asSony'sMinidisc format (which hasrandom access and editing features), it was not successful with consumers either. However, DCC proved that high quality digital recording could be achieved with a cheap simple mechanism using stationary heads.^{[citation needed]}

In the late 1980s, theRecording Industry Association of America (RIAA) unsuccessfully lobbied against the introduction of DAT devices into the U.S. Initially, the organization threatened legal action against any manufacturer attempting to sell DAT machines in the country. It later sought to impose restrictions on DAT recorders to prevent them from being used to copy LPs, CDs, and prerecorded cassettes. One of these efforts, theDigital Audio Recorder Copycode Act of 1987 (introduced bySen. Al Gore andRep. Waxman), initiated by CBS Records presidentWalter Yetnikoff, involved a technology calledCopyCode and required DAT machines to include a chip to detect attempts to copy material recorded with anotch filter,^[6] meaning that copyrighted prerecorded music, whether analog or digital, whether on LP, cassette, or DAT, would have distorted sound resulting from the notch filter applied by the publisher at the time of mastering for mass reproduction. ANational Bureau of Standards study showed that not only were the effects plainly audible, but that it was not even effective at preventing copying.^{[citation needed]}

This opposition by CBS softened after Sony, a DAT manufacturer, bought CBS Records in January 1988. By June 1989, an agreement was reached, and the only concession the RIAA would receive was a more practical recommendation from manufacturers to Congress that legislation be enacted to require that recorders have aSerial Copy Management System to prevent digital copying for more than a single generation.^[7] This requirement was enacted as part of theAudio Home Recording Act of 1992, which also imposedtaxes on DAT recorders and blank media. However, thecomputer industry successfully lobbied to havepersonal computers exempted from that act, setting the stage for massive consumer copying of copyrighted material on materials likerecordable CDs and by extension,filesharing systems such asNapster.^[8]

DAT was used professionally in the 1990s by the audio recording industry as part of an emerging all-digital production chain also including digital multi-track recorders anddigital mixing consoles that was used to create a fully digital recording. In this configuration, it is possible for the audio to remain digital from the first AD converter after themic preamp until it is in aCD player.^{[citation needed]}

In December 1987,The Guitar And Other Machines by the British post-punk bandThe Durutti Column, became the first commercial release on DAT. Later in May 1988,Wire released their albumThe Ideal Copy on the format.^[10] Several other albums from multiple record labels were also released as pre-recorded DATs in the first few years of the format's existence, in small quantities as well.Factory Records released asmall number of albums on the format, includingNew Order's best-selling compilationSubstance 1987, but many planned releases were cancelled.^[11]

DAT was envisaged by proponents as the successor format to analogue audio cassettes in the way that the compact disc was the successor to vinyl-based recordings. It sold well in Japan, where high-end consumer audio stores stocked DAT recorders and tapes into the 2010s and second-hand stores generally continued to offer a wide selection of mint condition machines. However, there and in other nations, the technology was never as commercially popular as CD or cassette. DAT recorders proved to be comparatively expensive and few commercial recordings were available. Globally, DAT remained popular, for a time, formaking andtrading recordings of live music (seebootleg recording), since available DAT recorders predated affordable CD recorders. In the 1990s, fans ofjam bands, such as theGrateful Dead andPhish, recorded and stored high-quality audience recordings of live concerts on the format.^[12]

The format was designed for audio use, but through the ISO Digital Data Storage standard was adopted for general data storage, storing from 1.3 to 80 GB on a 60 to 180 meter tape depending on the standard and compression. It is a sequential-access medium and is commonly used forbackups. Due to the higher requirements for capacity and integrity in data backups, a computer-grade DAT was introduced, called DDS (Digital Data Storage). Although functionally similar to audio DATs, only a few DDS and DAT drives (in particular, those manufactured byArchive forSGI workstations)^[13] are capable of reading the audio data from a DAT cassette. SGI DDS4 drives no longer have audio support; SGI removed the feature due to "lack of demand".^[14]

• ADAT
• Digital Audio Stationary Head
• Digital Data Storage
• Digital Tape Recording System
• Digital Compact Cassette
• Magnetic storage
• Magnetic tape
• MiniDisc
• NT (cassette)
• PCM adaptor
• ProDigi