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Compact audio cassette

From Kick Off World of Soccer - wikickoff

The Compact Cassette, often referred to as audio cassette, cassette tape, or simply cassette, is a widely used magnetic tape sound recording format. Although originally intended as a medium for dictation, improvements in fidelity led the Compact Cassette to supplant reel-to-reel tape recording in most applications.<ref name=Camras>Template:Cite book</ref> Its uses ranged from portable audio to home recording to data storage for computers. Between the 1970s and early 1990s, the cassette was one of the two most common formats for prerecorded music, alongside the LP and later the Compact Disc.<ref name=Daniel>Template:Cite book</ref>

Compact Cassettes consist of two miniature reels, between which a magnetic tape is passed and wound. These reels and their attendant parts are held inside a protective plastic shell. Two stereo pairs of tracks (four total) or two monaural audio tracks are available on the tape; one stereo pair or one monophonic track is played when the cassette is inserted with its 'A' side facing up, and the other when it is turned over (with the 'B' side up).<ref name=IEC>Template:Cite book</ref>

Image:Tdkc60cassette.jpg
Typical 60-minute Compact Cassette.

Contents

History

The compact audio cassette medium for audio storage was introduced in Europe by Philips in 1963, and in the U.S. in 1964, under the trademark name Compact Cassette. Although there were other magnetic tape cartridge systems at the time, the Compact Cassette became dominant as a result of Philips' decision (in the face of pressure from Sony) to license the format free of charge. It went on to become a popular (and re-recordable) alternative to the vinyl record deck during the 1970s.<ref name=Daniel>Template:Cite book</ref>

Introduction of music cassettes

The mass production of compact audio cassettes began in 1964 in Hanover, Germany. Prerecorded music cassettes (also known as Musicassettes; M.C. for short) were launched in Europe in late 1965. Musicassettes were introduced to the U.S. in September 1966 by The Mercury Record Company, a U.S. affiliate of Philips. The initial range consisted of 49 titles.<ref>Template:Cite journal</ref>

However, the system had been initially designed for dictation and portable use, with the audio quality of early players not well suited for music. Some early models also had unreliable mechanical design. In 1971 the Advent Corporation introduced their Model 201 tape deck which combined Dolby type B noise reduction and chromium dioxide (CrO2) tape. This resulted in the format being taken more seriously for musical use, and started the era of high-fidelity cassettes and players.<ref name=Camras>Template:Cite book</ref>

Image:WalkmanTPS-L2.jpg
1979 Sony Walkman

During the 1980s, the cassette's popularity grew further as a result of portable pocket recorders and high fi players such as Sony's Walkman, which used a body not much larger than a cassette tape. Some would partially collapse if they were not actually holding a cassette, with mechanical keys on one side, or electronic buttons on or display on the face. As the transistor radio defined small music in the 1960s, and the iPod in the 2000s, so did the Walkman define very small portable music in the 1980s, with cassette sales overtaking those of LPs.<ref name=Walkman>Template:Cite book</ref><ref name=Daniel>Template:Cite book</ref> Total vinyl record sales remained higher well into the 1980s due to greater sales of singles, although cassette singles achieved popularity for a period in the 1990s.<ref name=Walkman>Template:Cite book</ref>

Apart from the purely technical advances cassettes brought, they also served as catalysts for social change. Their durability and ease of copying helped bring underground rock and punk music behind the Iron Curtain, creating a foothold for western culture among the younger generations.<ref>Template:Cite book</ref> For similar reasons, cassettes became popular in developing nations. In 1970s India, they were blamed for bringing unwanted secular influences into traditionally religious areas. Cassette technology created a booming market for pop music in India, drawing criticism from conservatives while at the same time creating a huge market for legitimate recording companies and pirated tapes.<ref name=Manuel>Template:Cite book</ref> In some countries, particularly in the third world, cassettes still remain the dominant medium for purchasing and listening to music.<ref name=BBCthirdworld>Template:Cite web</ref>

Decline

In many western countries, the market for cassettes has declined seriously since its peak in the late 1980s. This has been particularly noticeable with pre-recorded cassettes, whose sales were overtaken by those of CDs during the early 1990s. In 1993 alone, CD shipments reached 5 million, up 21% from the year before, while cassette shipments dropped 7% to approximately 3.4 million.<ref>Template:Cite web</ref> By 2001, cassettes accounted for only 4% of all music sold in the United States.<ref>Template:Cite news</ref> Since then, the pre-recorded market has undergone further decline, with few retailers stocking them because they are no longer issued by the major music labels.<ref name=BBCthirdworld>Template:Cite web</ref> However, as of 2006, blank cassettes are still being produced and are sold at many retail stores, and facilities for cassette duplication remain available. Cassette recorders and players are gradually becoming more scarce, but are still widely available.<ref name=Stoll>Template:Cite web</ref>

Despite the wide availability of higher-fidelity media, cassettes also remain popular for specific applications, including car audio and other difficult environments. Cassettes are typically more rugged and resistant to dust, heat and shocks than most digital media (especially CDs). Their lower fidelity is not considered a serious drawback inside the typically noisy automobile interior. Although the "shock proof" buffering technology in many new CD players allows time to recover from intermittent skips, the cassette remains more resilient in the face of periodic and repeated shocks. However, cassettes generally have poor resistance to the excessive levels of heat encountered in parked cars during the summertime.

While digital voice recorders are now common, Compact Cassette (or frequently microcassette) recorders tend to be cheaper and of sufficient quality to serve as adjuncts or substitutes for note-taking in business and educational settings. Audiobooks, church services, and other spoken word material are still frequently sold on cassette, as lower fidelity is generally not a drawback for such content. While most publishers sell CD audiobooks, they usually also offer a cassette version at a lower price. In the audiobooks application, where recordings may may span several hours, cassettes also have the advantage of holding up to 120 minutes of dialog whereas the average CD holds less than 80.<ref name=Stoll>Template:Cite web</ref>

While cassettes and related equipment have become increasingly marginalized in the field of commercial music sales, recording on analog tape remains a desirable option for some. In 2002, Imation received an $11.9 million grant from the National Institute of Standards and Technology for research into increasing the data capacity of magnetic tape.<ref>Template:Cite web</ref> Some musicians still prefer to record their masters on magnetic tape for artistic reasons, and some consumers prefer to buy cassettes for the richness of analog sound.<ref name=Stoll>Template:Cite web</ref><ref>Template:Cite web</ref>

Features of the cassette

The cassette was a great step forward in convenience from reel-to-reel audio tape recording, though because of the limitations of the cassette's size and speed, it initially compared poorly in quality. Unlike the open reel format, the two stereo tracks lie adjacent to each other rather than a 1/3 and 2/4 arrangement. This permitted monaural cassette players to play stereo recordings "summed" as mono tracks and permitted stereo players to play mono recordings through both speakers. The tape is 3.18 mm wide (nominally 18 inch), with each stereo track being 0.79 mm wide (132 inch) and moves at 4.76 cm/s (178 ips) from left to right. <ref name=IEC>Template:Cite book</ref> For comparison, the typical open reel format in consumer use was ¼ inch (6.35 mm) wide, each stereo track being 116 inch (1.59 mm) wide, and running at either 3¾ or 7½ inches/s (9.5 or 19 cm/s).

Cassette types

Image:Cassette Write Protect IV.jpg
Notches on the top surface of the audio cassette indicate its type. The top cassette, with only write protect notches (here covered by write protect tabs), is a Type I. The next cassette down, with additional notches adjacent to the write protect notch, is a Type II. The bottom two cassettes, featuring the Type II notches plus an additional pair in the middle of the cassette are type IV (metal); note the removal of the tabs on the second of these, meaning the tape is write-protected.

The original magnetic material was based on gamma ferric oxide (Fe2O3). Circa 1970, 3M Company developed a cobalt volume-doping process combined with a double-coating technique to enhance overall tape output levels . This product was marketed as "High Energy" under its Scotch brand of recording tapes.<ref name=BTG>Template:Cite web</ref>

At about the same time chromium dioxide (CrO2) was introduced by BASF<ref>Template:Cite book</ref>, and then coatings using magnetite (Fe3O4) such as TDK's Audua were produced in an attempt to approach the sound quality of vinyl records. Cobalt-adsorbed iron oxide (Avilyn) was introduced by TDK in 1974 and proved very successful. Finally pure metal particles (as opposed to oxide formulations) were introduced in 1979 by 3M under the tradename Metafine. The tape coating on most Cassettes sold today as either "Normal" or "Chrome" consist of Ferric Oxide and Cobalt mixed in varying ratios (and using various processes) there are very few cassettes on the market that use a pure (CrO2) coating.<ref name=Daniel>Template:Cite book</ref>

These each had different bias and equalization requirements requiring specialized settings. The most common, iron oxide tapes (defined by an IEC standard as "Type I"), use 120 µS playback equalization, while chrome and cobalt-adsorbed tapes (IEC Type II) require 70 µS playback equalization. The record equalisations were also different (and had a much longer time constant). Sony tried a dual layer tape with both ferric oxide and chrome dioxide known as 'ferrichrome' (FeCr) (IEC Type III) but these were only available for a short time in the 1970s. Metal Cassettes (IEC Type IV), also use 70 µS playback equalization, and provide still further improvements in sound quality, as well as improved resistance to wear.<ref name=BTG>Template:Cite web</ref> The quality is normally reflected in the price; Type I cassettes are generally cheapest, and Type IV usually the most expensive. BASF developed a chrome cassette designed for use with 120 microsecond playback equalisation but this idea only caught on for commercially pre-recorded cassettes.<ref name=Daniel>Template:Cite book</ref>

Notches on top of the cassette shell indicate the type of tape within. Type I cassettes only have write-protect notches, Type II have an additional pair next to the write protection ones, and Type IV (metal) have a third set in the middle of the cassette shell. These allow cassette decks to automatically detect the tape type and select the proper bias and equalization.

Playback length

Image:CassetteTypes1.jpg
Cassettes of varying tape quality and playing time.

Tape length is usually measured in minutes total playing time. The most popular varieties are C46 (23 minutes per side) and C60 (30 minutes per side), C90, and C120. The C46 and C60 lengths are typically 15-16 µm thick, but C90s are 10-11 µm and C120s are just 9 µm thick rendering them more susceptible to stretching or breakage. Some vendors are more generous than others, providing 132 meters or 135 meters rather than 129 meters of tape for a C90 cassette. C180 and even C240 tapes were available at one time, but these were extremely thin and fragile and suffered badly from effects such as print-through which made them unsuitable for general use. Other lengths are (or were) also available from some vendors, including C10 and C15 (useful for saving data from early home computers), C50, C70, C74, C80, C100, C105, C110 and C180.<ref name=BTG>Template:Cite web</ref>

Some companies included a complimentary blank cassette with their portable cassette recorders in the early 1980s. Panasonic's was a C14 and came with a song recorded on side one, and side two blank. Except for C74 and C100, such non-standard lengths have always been hard to find, and tend to be more expensive than the more popular lengths. Home taping enthusiasts may have found them useful for fitting an album neatly on one or both sides of a tape. For instance, the initial maximum playback time of Compact Discs was 74 minutes, explaining the relative popularity of C74 cassettes.

Image:Cassetteinternals.jpg
Inside a cassette. The tape is pressed into close contact with the head by the pressure pad; guide rollers help keep the tape in the correct position. Smooth running is assisted by a slippery liner between the reels and the shell - here the liner is transparent. The magnetic shield reduces pickup of stray signals by the heads of the player.

Write-protection

All cassettes include a write protection mechanism to prevent re-recording and accidental erasure of important program material. Each side of the cassette has a plastic tab on the top that may be broken off, leaving a small indentation in the shell. This indentation allows the entry of a sensing lever which prevents the operation of the recording function when the cassette is inserted into a cassette deck. If the cassette is held with one of the labels facing the user and the tape opening at the bottom, the write-protect tab for the corresponding side is at the top-left.

If later required, a piece of adhesive tape can be placed over the indention to record over the "protected" material, or (on some decks), the lever can be manually depressed to record on a protected tape. Extra care is required when doing this with high bias tape cassettes; the additional indents (adjacent to the write-protect tabs) used to differentiate them from normal bias cassettes should not be inadvertently covered up. One manufacturer, Bib, even made small plastic inserts to fit into the record tab indent, and a special tool for removing them.

Cassette Players and Recorders

Main article: Cassette deck

Stereo recorders were known as "cassette decks", after the reel-to-reel "decks". Many formats of cassette players and recorders have evolved over the years. Initially all were top loading, usually with cassette on one side, VU meters and recording level controls on the other side. One of the oldest surviving forms is the long box with speaker above the cassette compartment with "piano key" controls near the handle still emulated on many software control panels. The cassette deck also introduced the symbols of square for stop, right pointing triangle for play, double triangles for fast forward and rewind, red dot for record, and the pause button. Older models used combinations of levers and sliding buttons for control.

Image:Nakamichi RX 505 Front edited.jpg
Nakamichi RX-505 audio cassette deck

A major innovation was the front loading arrangement. Pioneer's angled cassette bay and the exposed bays of some Sansui models were eventually standardized as a front-loading door into which a cassette would be loaded. Later models would adopt electronic buttons, and replace conventional meters (which could be "pegged" when overloaded) with electronic LED or flourescent displays, with level controls typically either being controlled by rotary controls or side-by-side sliders. BIC briefly offered models which could be run at higher speeds, but Nakamichi was widely recognized as one of the first companies to create decks which rivaled reel-to-reel decks with frequency response from the full 20-20,000 Hz range, low noise, and very low wow and flutter.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> As they became aimed at more casual users, fewer decks had microphone inputs. Dual decks became popular and incorporated into home entertainment systems of all sizes for tape dubbing. Even as CD recorders are becoming more popular, some incorporate cassette decks for professional applications.

Image:Ghettoblaster-family.jpg
An assortment of boomboxes

Another format which made an impact on culture in the 1980s was the "boombox" which combined the portable cassette deck with speakers capable of producing significant sound levels. Boomboxes became synonymous with urban youth culture in entertainment. Spike Lee's Do The Right Thing features one with comically exaggerated proportions, and Spock disables the user of one in a scene from 1986's Star Trek IV: The Voyage Home.

Applications for car stereos varied widely. Auto manufacturers in the US would typically fit a cassette slot into their standard radio faceplates, while Europe and Asia would standardize on DIN and double DIN sized faceplates. Many manufacturers would either trade cassette for a CD slot or offer multiple openings to accomodate a CD player and cassette deck at the same time.

Although the cassettes themselves were relatively durable, the players required regular maintenance to perform properly. Head cleaners were cassette-shaped devices that could be inserted into a tape deck to polish the heads and remove smudges and dirt. Most head cleaners also used magnets to degauss the deck, which kept sound from becoming distorted. A common mechanical problem occurred when a worn-out or dirty player rotated the supply reel faster than the take-up reel or failed to release the heads from the tape upon ejection. This would cause the magnetic tape to be fed out through the bottom of the cassette and become tangled in the mechanism of the player. In these cases the player was said to have "eaten" the tape, and it often destroyed the playability of the cassette altogether.<ref>Template:Cite web</ref>

Applications

Audio

The Compact Cassette was originally intended for use in dictation machines. In this capacity, some later-model cassette-based dictation machines could also run the tape at half speed (1516 ips) as playback quality was not critical. The Compact Cassette soon became a popular medium for distributing prerecorded music—initially through The Philips Record Company (and subsidiary labels Mercury and Philips in the US). As of 2006, one finds cassettes used for a variety of purposes such as journalism, oral history, meeting and interview transcripts and so on. However, they are starting to give way to Compact Discs and more "compact" storage media.

Home studio

In the 1980s, Tascam introduced the Portastudio line of four and eight-track cassette recorders for home studio use, allowing amateur musicians (and some professionals) to overdub themselves easily. To increase audio quality in these recorders, the tape speed is doubled in comparison to the standard; additionally, dbx noise reduction provides compansion (compression of the signal during recording and equal & opposite expansion of the signal during playback) which yields increased dynamic range by lowering the noise level and increasing the maximum signal level before distortion occurs. Multi-track cassette recorders with built-in mixer and signal routing features provide a wide range of features and benefits from easy-to-use beginner units up to professional level recording systems.<ref>Template:Cite web</ref>

Home dubbing

Image:Dualdeck.jpg
A Magnavox dual deck recorder with high-speed dubbing

Most cassettes were sold blank and used for recording (dubbing) the owner's records (as backup or to make compilations), their friends' records or music from the radio. This practice was condemned by the music industry with such slogans as "Home Taping is Killing Music". However, many claimed that the medium was ideal for spreading new music and would increase sales, and strongly defended at least their right to copy their own records onto tape. Cassettes were also a boon to people wishing to tape concerts (unauthorized or authorized) for sale or trade, a practice tacitly or overtly encouraged by many bands with a more counterculture bent such as the Grateful Dead. Blank Compact Cassettes also were an invaluable tool to spread the music of unsigned acts, especially within Tape trading networks.

Various legal cases arose surrounding the dubbing of cassettes. In the UK, in the case of CBS Songs vs Amstrad (1988), the House of Lords found in favour of Amstrad that producing equipment that facilitated the dubbing of cassettes, in this case a high-speed twin cassette deck that allowed one cassette to be copied directly onto another, did not constitute the infringement of copyright.<ref>CBS Songs v. Amstrad (1988)</ref> In a similar case, a shop owner who rented cassettes and sold blank tapes was not liable for copyright infringement even though it was clear that his customers were likely dubbing them at home.<ref>CBS v. Ames (1982)</ref> In both cases, the courts held that manufacturers and retailers could not be held accountable for the actions of consumers.

Data recording

Image:Commodore-Datassette.jpg
A Datassette recorder for Commodore computers

The Hewlett Packard HP 9830 was one of the first desktop computers in the early 1970s to use automatically controlled cassette tapes for storage. It could save and find files by number, using a clear leader to detect the end of tape. These would be replaced by specialized cartridges such as the 3M DC-series. Many of the earliest microcomputers implemented the Kansas City standard for digital data storage. Most home computers of the late 1970s and early 1980s could use cassettes for data storage as a cheaper alternative to floppy disks, though users often had to manually stop and start a cassette recorder. Even the first version of the IBM PC of 1981 had a cassette port and a command in its ROM BASIC programming language to use it. However, this was seldom used, as even then floppy drives had become commonplace in high-end machines. The typical encoding method was simple FSK which resulted in typical data rates 500 to 2000 bit/s, although some games used special faster loading routines, up to around 4000 bit/s. A rate of 2000 bit/s equates to a capacity of around 660 kilobytes per side of a 90 minute tape.

The use of better modulation techniques like QPSK or those used in modern modems, combined with the improved bandwidth and signal to noise ratio of newer cassette tapes allowed much greater capacities and speeds (10–17 kB/s for data rate, and up to 60 MB on each cassette). These were typically used as hard disk backup for PCs in the late 1980s. They also found use during the 1980s in data loggers for scientific and industrial equipment.

Successors

Image:CassetteAndMicrocassette.jpg
A Compact Cassette and a microcassette

Technical development of the cassette effectively ceased when digital recordable media such as DAT and MiniDisc were introduced in the late 1980s and early 1990s. Anticipating the switch from analog to digital, major companies such as Sony shifted their focus to new media.<ref>Template:Cite news</ref> In 1992, Philips introduced the Digital Compact Cassette (DCC), a DAT-like tape in the same form factor as the compact audio cassette. It was aimed primarily at the consumer market. A DCC deck could play back both types of cassettes. Unlike DAT, which was accepted in professional usage because it could record without lossy compression effects, DCC was not a success in either home or mobile environments, and was discontinued in 1996.<ref>Template:Cite news</ref>

The microcassette has in many cases supplanted the full-sized audio cassette in situations where voice-level fidelity is all that is required, such as in dictation machines and answering machines. Even these, in turn, are starting to give way to digital recorders of various descriptions.<ref>Template:Cite web</ref> Since the rise of cheap CD-R discs, and flash memory-based MP3 and iPod-like players, the phenomenon of "home taping" has effectively switched to recording to Compact Disc or downloading from commercial or music sharing websites.<ref>Template:Cite web</ref>

Because of consumer demand, the cassette has remained influential on design nearly two decades after its decline. As the Compact Disc grew in popularity, cassette-shaped audio adapters were developed to provide an economical and clear way to obtain CD functionality in vehicles equipped with cassette decks. A portable CD player would have its analog line-out connected to the adapter, which in turn fed the signal to the head of the cassette deck. These adapters continue to function with MP3 players players as well, and are generally more reliable than the FM transmitters that must be used to adapt CD players to MP3s. Mp3 players shaped as audio cassettes have also become available, which can be inserted into any audio cassette player and communicate with the head as if they were normal cassettes.<ref>Template:Cite web</ref><ref>Template:Cite web</ref>

See also

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References

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External links

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