A TDK D-C60 cassette, a common speech-quality tape with a 60-minute playing time, in a housing similar to that of the original Philips' Compact Cassette specification
|Media type||Magnetic tape|
|Capacity||Typically 30 or 45 minutes of audio per side (C60 and C90 formats respectively); less common capacities included C15, C20, C30, C120 and C180.|
|Read mechanism||Tape head|
|Write mechanism||Magnetic recording head|
|Usage||Audio and data storage|
The Compact Cassette or Musicassette (MC), also commonly called cassette tape, audio cassette, or simply tape, is an obsolete magnetic tape recording format for audio recording and playback. Compact cassettes come in two forms, either already containing content as a pre-recorded cassette, or as fully recordable "blank" cassette. It was designed originally for dictation machines, but improvements in fidelity led the Compact Cassette to supplant the Stereo 8-track cartridge and reel-to-reel tape recording in most non-professional applications. Its uses ranged from portable audio to home recording to data storage for early microcomputers. Between the early 1970s and the late 1990s, the cassette was one of the two most common formats for prerecorded music, first alongside the LP record and later the Compact Disc.
Compact Cassettes consist of two miniature spools, between which a magnetically coated plastic tape is passed and wound. These spools and their attendant parts are held inside a protective plastic shell. Two stereo pairs of tracks (four total) or two monaural analog audio tracks are available on the tape; one stereo pair or one monophonic track is played or recorded when the tape is moving in one direction and the second pair when moving in the other direction. This reversal is achieved either by manually flipping the cassette or by having the machine itself change the direction of tape movement ("auto-reverse").
In 1935, decades before the introduction of the Compact Cassette, AEG released the first reel-to-reel tape recorder (in German: Tonbandgerät), with the commercial name "Magnetophon", based on the invention of the magnetic tape (1928) by Fritz Pfleumer, which used similar technology but with open reels (for which the tape was manufactured by BASF). These instruments were still very expensive and relatively difficult to use and were therefore used mostly by professionals in radio stations and recording studios. For private use the (reel-to-reel) tape recorder was not very common and only slowly took off from about the 1950s; with prices between 700 and 1,500 DM (which would now be about € 1600 to 3400) such machines were still far too expensive for the mass market and their vacuum tube construction made them very bulky. In the early 1960s, however, the weights and the prices dropped when vacuum tubes were replaced by transistors. Reel-to-reel tape recorders then became more common in household use, though never but a small fraction of the number of homes using long playing record disc players.
In 1958, following four years of development, RCA Victor introduced the stereo, quarter-inch, reversible, reel-to-reel RCA tape cartridge. It was a cassette, big (5" × 7"), but offered few pre-recorded tapes; despite multiple versions, it failed.
In 1962 Philips invented the Compact Cassette medium for audio storage, introducing it in Europe on 30 August 1963 (at the Berlin Radio Show), and in the United States (under the Norelco brand) in November 1964, with the trademark name Compact Cassette.
Although there were other magnetic tape cartridge systems, Philips' Compact Cassette became dominant as a result of Philips' decision in the face of pressure from Sony to license the format free of charge. Philips also released the Norelco Carry-Corder 150 recorder/player in the U.S. in November 1964. By 1966 over 250,000 recorders had been sold in the US alone and Japan soon became the major source of recorders. By 1968, 85 manufacturers had sold over 2.4 million players.
In the early years, sound quality was mediocre, but it improved dramatically by the early 1970s when it caught up with the quality of 8-track tape and kept improving. The Compact Cassette went on to become a popular (and re-recordable) alternative to the 12-inch vinyl LP during the late 1970s.
Introduction of music cassettes 
The mass production of Compact 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. The Mercury Record Company, a U.S. affiliate of Philips, introduced M.C. to the U.S. in July 1966. The initial offering consisted of 49 titles. However, the system had been designed initially 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 that combined Dolby type B noise reduction and chromium dioxide (CrO2) tape, with a commercial-grade tape transport mechanism supplied by the Wollensak camera division of 3M Corporation. This resulted in the format being taken more seriously for musical use, and started the era of high fidelity cassettes and players.
During the 1980s, the cassette's popularity grew further as a result of portable pocket recorders and high-fidelity ("hi-fi") players, such as Sony's Walkman (1979), which used a body not much larger than the cassette tape itself, with mechanical keys on one side, or electronic buttons or display on the face. Sony's WM-10 was even smaller than the cassette itself and expanded to hold and play a cassette.
Like the transistor radio in the 1950s and 1960s, the portable CD player in the 1990s, and the MP3 player in the 2000s, the Walkman defined the portable music market of a decade, in its case the 1980s, with cassette sales overtaking those of LPs. 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.
Apart from the purely technological 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. For similar reasons, cassettes became popular in developing nations.
One of the most famous political uses of cassette tapes was the dissemination of sermons by the Ayatollah Khomeini throughout Iran before the 1979 Iranian Revolution, in which Khomeini urged the overthrow of the regime of the Shah, Mohammad Reza Pahlavi.
In 1970s India, they were blamed for bringing unwanted Christian and Islamic influences into traditionally Sikh and Hindu areas. Cassette technology was 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 as well as pirated tapes. Until recently, cassettes remained the dominant medium for purchasing and listening to music in some developing countries.
In Western Europe and North America, the market for cassettes has declined sharply since its peak in the late 1980s. This has been noticeable particularly with pre-recorded cassettes, whose sales were overtaken by those of Compact Discs during the early 1990s. By 1993, annual shipments of CD players had reached 5 million, up 21% from the year before, while cassette player shipments had dropped 7% to approximately 3.4 million. The decline continued such that in 2001 cassettes accounted for only 4% of all music sold. 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. Sales of pre-recorded music cassettes in the U.S. dropped from 442 million in 1990 to 274,000 by 2007. 2009 saw another record low with 34,000 cassettes sold. Most of the major U.S. music companies had discontinued them by late 2002 or 2003. However, as of 2011[update], 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 becoming gradually scarcer, but are still widely available and featured in a notable percentage of Hi-Fi systems.
Cassettes remained popular for specific applications, such as car audio, well into the 1990s. Cassettes and their players typically were more rugged and resistant to dust, heat, and shocks than the main digital competitor (the CD). Their lower fidelity was not considered a serious drawback inside the typically noisy automobile interior of the time. However, the advent of "shock proof" buffering technology in CD players, the reduction of in-car noise levels, the general heightening of consumer expectations, and the introduction of CD auto-changers meant that, by the early 2000s, the CD player rapidly was replacing the cassette player as the default audio component in the majority of new vehicles in Europe and America. However during the 2010s, the CD player is now being supplanted by USB flash drives which offer far more recording/playback time than either CDs or cassettes.
While digital voice recorders are now common, Compact Cassette (or frequently Microcassette) recorders may 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 sold frequently on cassette, as lower fidelity generally is not a drawback for such content. While most publishers sell CD audiobooks, usually they also offer a cassette version at the same price. In the audiobooks application, where recordings may span several hours, cassettes also have the advantage of holding up to 150 minutes of material, whereas the average CD holds less than 80.
While cassettes and related equipment have become increasingly marginal in commercial music sales, recording on analog tape remains a desirable option for some, though that method is being overtaken by portable digital recorders. Musicians in the indie rock community have shown slight interest in releasing cassettes. Such artists as Dirty Projectors and Deerhunter have made recent titles available on cassette, and Thurston Moore of Sonic Youth has claimed in 2009 "I only listen to cassettes."
Among the last in the developed countries to leave the cassette format are artists and groups belonging to the "dansband" genre, many of whom still, in the early 2000s, had released their albums both to CD and to cassettes. Since many of their fans now are older, they often belong to a generation less interested in buying a CD player. However, also in this genre, fewer artists and groups release recordings on cassette. As late as 2006, Lasse Stefanz and Torgny Melins released their latest albums to both cassette and CD.
In India, film and devotional music continues to be released in the cassette format due to its low cost.
In South Korea, the early English education boom for toddlers encourages a continuous demand for English language cassettes, as of 2011, due to the affordable cost.
In recent years, the Compact Cassette format has seen a revival with independent record labels ("indie" labels) preferring to issue releases in this format due to its low cost and the difficulty in sharing tape music over the internet. Underground and DIY communities release regularly, and sometimes exclusively, on cassette format, particularly in experimental music circles and to a lesser extent in hardcore punk, death metal, and black metal circles, out of a fondness for the format.
The cassette was a great step forward in convenience from reel-to-reel audio tape recording, although, because of the limitations of the cassette's size and speed, it initially compared poorly in quality. Unlike the 4-track stereo open-reel format, the two stereo tracks of each side lie adjacent to each other, rather than being interleaved with the tracks of the other side. 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 3.81 mm (0.150 in) wide, with each stereo track 0.6 mm wide and an unrecorded guard band between each track. The tape moves at 4.76 cm/s (1⅞ inch/s) from left to right. For comparison, the typical open-reel format in consumer use was 6.35 mm (¼ inch) wide, each stereo track nominally 1.59 mm (1⁄16 inch) wide, and running at either twice or four times the speed of a cassette.
Cassette types 
Cassette tapes are made of a polyester type plastic film with a magnetic coating. 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. Inexpensive cassettes commonly are labeled "low-noise," but typically are not optimized for high frequency response. For this reason, some low-grade IEC Type I tapes have been marketed specifically as better suited for data storage than for sound recording.
At about the same time, chromium dioxide (CrO2) was introduced by DuPont, the inventor of the particle, and BASF, the inventor of magnetic recording, 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-absorbed 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 trade name Metafine. The tape coating on most Cassettes sold today as either "Normal" or "Chrome" consists 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.
Simple voice recorders are designed to work with standard ferric formulations. Later tape decks usually are built with switches or detectors for the different bias and equalization requirements for high performance tapes. The most common, iron oxide tapes (defined by an IEC standard as "Type I"), use 120 µs equalization, while chrome and cobalt-absorbed tapes (IEC Type II) require 70 µs equalization. The recording "bias" equalizations also were different (and had a much longer time constant). BASF and Sony tried a dual layer tape with both ferric oxide and chrome dioxide known as 'ferrichrome' (FeCr) (IEC Type III), but these were available for only a short time in the 1970s. Metal Cassettes (IEC Type IV) also use 70 µs equalization, and provide still further improvement in sound quality as well as durability. The quality normally is reflected in the price; Type I cassettes generally are the cheapest, and Type IV are usually the most expensive. BASF chrome tape used in commercially pre-recorded cassettes used type I equalization to allow greater high-frequency dynamic range for better sound quality, but the greater selling point for the music labels was that the Type I cassette shell could be used for both ferric and for chrome music cassettes.
Notches on top of the cassette shell indicate the type of tape within. Type I cassettes have only 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 later cassette decks to detect the tape type automatically and select the proper bias and equalization. Virtually all recent hi-fi systems (with cassette decks) lack this feature; only a small niche of cassette decks (hi-fi separates) have the tape type selector. Playing Type II and IV tapes on a player without detection will produce exaggerated treble, but it may not be noticeable because such devices typically have amplifiers that lack extended high-frequency output. Recording on these units, however, results in very low sound reproduction, and sometimes distortion and noise is heard. Also, these cheaper units cannot erase high bias or metal bias tapes. Attempting to do so will result in an incomplete erasure. This is due to the fact that the bias levels for high and metal position requires greater levels.
Tape length 
Tape length usually is measured in minutes of total playing time. The most popular varieties are C46 (23 minutes per side), C60 (30 minutes per side), C90, and C120. The C46 and C60 lengths typically are 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 (433 feet) or 135 meters (442 feet) rather than 129 meters (423 feet) of tape for a C90 cassette. Even C180 tapes were available at one time, but these were extremely thin and fragile and suffered from such effects as print-through, which made them unsuitable for general use. 150 minute length is still available from Maxell (UR 150), Sony (CDixI 150) and TDK (TDK AE 150).
Although the TDK-D C180 was produced for a decade (1972–82 ), it is very rare, because of several technical flaws. The tape had to be so thin that it was nearly transparent and therefore had fewer particles to magnetize, resulting in a poor sound quality and even worse durability. It required a strong motor to be driven, and had high wow and flutter. Finally, it took a relatively long time to rewind.
Other lengths are (or were) also available from some vendors, including C10 and C15 (useful for saving data from early home computers and in telephone answering machines), C30, C40, C50, C54, C64, C70, C74, C80, C84, C100, C105, and C110. As late as 2010, Thomann still offered C10, C20, C30 and C40 IEC Type II tape cassettes for use with 4- and 8-track portastudios.
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 a blank side two. Except for C74 and C100, such non-standard lengths always have been hard to find, and tend to be more expensive than the more popular lengths. Home taping enthusiasts may have found certain lengths 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.
All cassettes include a write protection mechanism to prevent re-recording and accidental erasure of important 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 that 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. Occasionally, manufacturers provided a movable panel that could be used to enable or disable write-protect on tapes.
If later required, a piece of adhesive tape can be placed over the indentation to bypass the protection, or (on some decks), the lever can be manually depressed to record on a protected tape. Extra care is required to avoid covering the additional indents on high bias or metal bias tape cassettes adjacent to the write-protect tabs.
Tape leaders 
In most cassettes the magnetic tape was attached to each spool with a leader, usually made of strong plastic (see right-hand image). This leader protected the weaker magnetic tape from the shock occurring when the tape reached the end. Leaders can be complex: a plastic slide-in wedge anchors a short fully opaque plastic tape to the take-up hub; one or more tinted semi-opaque plastic segments follow; the clear leader (a tintless semi-opaque plastic segment) follows, which wraps almost all the way around the supply reel, before splicing to the magnetic tape itself. The clear leader spreads the shock load to a long stretch of tape instead of to the microscopic splice. Various patents have been issued detailing leader construction and associated tape player mechanisms to detect leaders. Cassette tape users would also use spare leaders to repair broken tapes.
The disadvantage with tape leaders was that the sound recording or playback did not start at the beginning of the tape, forcing the user to cue forward to the start of the magnetic section. For certain applications, such as dictation, special cassettes containing leaderless tapes were made, typically with stronger material and for use in machines that had more sophisticated end-of-tape prediction.
Endless loop cassette 
Some cassettes were made to play a continuous loop of tape without stopping. Lengths available are from around 30 seconds to a standard full length. They are used in situations where a short message or musical jingle is to be played, either continuously or whenever a device is triggered, or whenever continuous recording or playing is needed. Some include a sensing foil on the tape to allow tape players to re-cue. From as early as 1969 various patents have been issued, covering such uses as uni-directional, bi-directional, and compatibility with auto-shut-off and anti-tape-eating mechanisms.
For professional broadcasters wishing to play jingles, commercials or other short audio insert see "NAB" Fidelipac endless loop media.
While ubiquitous and accessible, cassette playback suffered from some flaws frustrating to both professionals and home recording enthusiasts. Tape speed could vary between devices, resulting in pitch that was too low or too high. Speed often was calibrated at the factory, and could not be changed by users. The slow tape speed increased tape hiss and noise, and in practice delivered higher values of wow-and-flutter. Different tape formulation and noise reduction schemes artificially boosted or cut high frequencies and inadvertently elevated noise levels. Noise reduction also adds some artifacts to the sound, which a trained ear can hear sometimes quite easily.
Cassette players and recorders 
The first cassette machines (e.g. the Philips EL 3300, introduced in August, 1963) were simple mono-record and -playback units. Early machines required attaching an external dynamic microphone. Most units from the 1980s onwards also incorporated built-in condenser microphones, which have extended high-frequency response, but may also pick up noises from the recorder motor. A portable recorder format still common today is a long box, the width of a cassette, with a speaker at the top, a cassette bay in the middle, and "piano key" controls at the bottom edge. Another format is only slightly larger than the cassette, also adapted for stereo "Walkman" player applications. The markings of "piano key" controls soon were standardized, and are a legacy still emulated on many software control panels. These symbols are commonly a square for "stop", a vertically pointed triangle with a line under it for "eject", a right-pointing triangle for "play", double triangles for "fast-forward" and "rewind", a red dot for "record", and a vertically divided square (two rectangles side-by-side) for "pause".
Stereo recorders eventually evolved into high fidelity and were known as cassette decks, after the reel-to-reel decks. Hi-Fi cassette decks, in contrast to cassette recorders and cassette players, often didn't have built-in amplification or speakers. Many formats of cassette players and recorders have evolved over the years. Initially all were top loading, usually with cassette on one side, and VU meters and recording level controls on the other side. Older models used combinations of levers and sliding buttons for control.
A major innovation was the front-loading arrangement. Pioneer's angled cassette bay and the exposed bays of some Sansui models eventually were 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[clarification needed]) with electronic LED or vacuum fluorescent displays, with level controls typically being controlled by either rotary controls or side-by-side sliders. BIC and Marantz briefly offered models that could be run at double speeds, but Nakamichi was widely recognized as one of the first companies to create decks that rivaled reel-to-reel decks with frequency response from the full 20–20,000 Hz range, low noise, and very low wow and flutter. The 3-head closed-loop dual capstan Nakamichi 1000 (1973) is one early example. Unlike typical cassette decks that use a single head for both record and playback plus a second head for erasing, the Nakamichi 1000, like the better reel-to-reel recorders, used three separate heads to optimize these functions.
Other contenders for the highest "HiFi" quality on this medium were two companies already widely known for their excellent quality reel-to-reel tape recorders: Tandberg and Revox (consumer brand of the Swiss professional Studer company for studio equipment). Tandberg started with combi-head machines, such as the TCD 300, and continued with the TCD 3x0 series with separate playback and recording heads. All TCD-models possessed dual-capstan drives, belt-driven from a single capstan motor and two separate reel motors. Frequency range extended to 18 kHz. After a disastrous overinvestment in colour television production, Tandberg folded and revived without the HiFi-branch these came from.
Revox went one step further: after much hesitation about whether to accept cassettes as a medium capable for meeting their strict standards from reel-to-reel recorders at all, they produced their B710MK I (Dolby B) and MK II (Dolby B&C) machines. Both cassette units possessed double capstan drives, but with two independent, electronically controlled capstan motors and two separate reel motors. The head assembly moved by actuating a damped solenoid movement, eliminating all belt drives and other wearable parts. These machines rivaled the Nakamichi in frequency and dynamic range. The B710MKII also achieved 20–20,000 Hz and dynamics of over 72 dB with Dolby C on chrome and slightly less dynamic range, but greater headroom with metal tapes and Dolby C. Revox adjusted the frequency range on delivery with many years of use in mind: when new, the frequency curve went upwards a few dB at 15–20 kHz, aiming for flat response after 15 years of use, and headwear to match.
A last step taken by Revox produced even more-advanced cassette drives with electronic finetuning of bias and equalization during recording. Revox also produced amplifiers, a very expensive FM tuner, and a pickup with a special parallel-arm mechanism of their own design. After releasing that product, Studer encountered financial difficulties. It had to save itself by folding its Revox-branch and all its consumer products (except their last reel-to-reel recorder, the B77).
While some might say that Nakamichi violated the tape recording standards to achieve the highest dynamics possible, producing non-compatible cassettes for playback on other machines, the reasons for this are more complex than they appear on the surface. Different interpretations of the cassette standard resulted in a 4 dB ambiguity at 16 kHz. Technically, both camps in this debate were still within the original cassette specification as no tolerance for frequency response was provided above 12.5 kHz and all calibration tones above 12.5 kHz are considered optional.
A third company, the Danish Bang & Olufsen, invented an improved system for improving headroom at high frequencies, to reduce tape saturation despite lower bias levels. This "head room extension method, HX" was called Dolby HX Pro in full and patented. HX Pro was adopted by other manufacturers, including Technics, while Aiwa incorporated the technology into their top of the range personal stereos, as well as into their static machines.
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. Although the quality would suffer each time a source was copied, there are no mechanical restrictions on copying from a record, radio, or another cassette source. Even as CD recorders are becoming more popular, some incorporate cassette decks for professional applications.
Another format that made an impact on culture in the 1980s was the radio-cassette, aka the "boom box" (a name used commonly only in the USA), which combined the portable cassette deck with a radio tuner and speakers capable of producing significant sound levels. These devices became synonymous with urban youth culture in entertainment, which led to the somewhat derisive nickname "ghetto blaster."
Applications for car stereos varied widely. Auto manufacturers in the U.S. typically would fit a cassette slot into their standard large radio faceplates. Europe and Asia would standardize on DIN and double DIN sized faceplates. In the 1980s, a high-end installation would have a Dolby AM/FM cassette deck, and they rendered the 8-track cartridge obsolete in car installations because of space, performance, and audio quality. In the 1990s and 2000s, as the cost of building CD players declined, many manufacturers offered a CD player. The CD player eventually supplanted the cassette deck as standard equipment, but some cars, especially those targeted at older drivers, were offered with the option of a cassette player, either by itself or sometimes in combination with a CD slot. Most new cars can still accommodate aftermarket cassette players, and the auxiliary jack advertised for MP3 players can be used also with portable cassette players, but 2011 is the first model year for which no manufacturer offered factory-installed cassette players.
Although the cassettes themselves were relatively durable, the players required regular maintenance to perform properly. Head cleaning may be done with long swabs, soaked with isopropyl alcohol, or cassette-shaped devices that could be inserted into a tape deck to remove buildup of iron-oxide from the heads, tape-drive capstan, and pinch-roller. Some otherwise normal recording tapes included sections of leader that could clean the tape heads. One of the concerns of the time however was the use of abrasive cleaning tape. Some of the cleaning tapes actually felt rough to the touch and were considered damaging to the heads.
Similarly shaped demagnetizers 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 spool faster than the take-up spool 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, and resulted in the common sight of tangled tape on the side of the road. Cutting blocks, analogous to those used for open-reel 1/4" tape were readily available, though used mainly for retrieving valued recordings, could be used to remove the damaged portion, or repair the break in the tape. Creation of compilations usually was by re-recording rather than splicing sections of songs because of the much smaller tape area.
The Compact Cassette originally was intended for use in dictation machines. In this capacity, some later-model cassette-based dictation machines could also run the tape at half speed (15⁄16 in/s) as playback quality was not critical. The cassette soon became a popular medium for distributing prerecorded music—initially through The Philips Record Company (and subsidiary labels Mercury and Philips in the U.S.). As of 2009, one still finds cassettes used for a variety of purposes, such as journalism, oral history, meeting and interview transcripts, audio-books, and so on. However, they are starting to give way to Compact Discs and more "compact" digital storage media.
The cassette quickly found use in the commercial music industry. One artifact found on some commercially produced music cassettes was a sequence of test tones, called SDR (Super Dynamic Range, also called XDR, or eXtended Dynamic Range) soundburst tones, at the beginning and end of the tape, heard in order of low frequency to high. These were used during SDR/XDR's duplication process to gauge the quality of the tape medium. Many consumers objected to these tones since they were not part of the recorded music.
News reporting, documentary, and human interest broadcast operations often used portable Marantz PMD-series recorders for the recording of speech interviews. The key advantages of the Marantz portable recorders were the accommodation of professional microphones with an XLR connector, normal and double tape speed recording for extended frequency response, Dolby and dbx noise reduction systems, manual or automatic gain control (AGC) level control, peak limiter, multiple tape formulation accommodation, microphone and line level input connections, unbalanced RCA stereo input and output connections, live or tape monitoring, VU meter, headphone jack, playback pitch control, and operation on AC power or batteries optimized for long duration. Unlike less-expensive portable recorders that were limited to automatic gain control (AGC) recording schemes, the manual recording mode preserved low noise dynamics and avoided the automatic elevation of noise.
Home studio 
In the simplest configuration, rather than playing a pair of stereo channels of each side of the cassette, the typical "portastudio" used a four-track tape head assembly to access four tracks on the cassette at once (with the tape playing in one direction). Each track could be recorded to, erased, or played back individually, allowing musicians to overdub themselves and create simple multitrack recordings easily, which could then be mixed down to a finished stereo version on an external machine. To increase audio quality in these recorders, the tape speed sometimes was doubled to 3¾ inches per second, in comparison to the standard 17⁄8 ips; additionally, dbx, Dolby B or Dolby C noise reduction provided compansion (compression of the signal during recording with equal and 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 ranged from easy-to-use beginner units up to professional-level recording systems.
Home dubbing 
Most cassettes were sold blank, and used for recording (dubbing) the owner's records (as backup, to play in the car, or to make mixtape compilations), their friends' records, or music from the radio. This practice was condemned by the music industry with such alarmist 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 their right to copy at least their own records onto tape. For a limited time in the early 1980s Island Records sold chromium dioxide “One Plus One” cassettes that had an album prerecorded on one side and the other was left blank for the purchaser to use. 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, such as the Grateful Dead, with a more counterculture bent. Blank 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 v. Amstrad (1988), the House of Lords found in favor 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. 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 likely were dubbing them at home. In both cases, the courts held that manufacturers and retailers could not be held accountable for the actions of consumers.
As an alternative to home dubbing, in the late 1980s, the Personics company installed booths in record stores across America that allowed customers to make personalized mixtapes from a digitally encoded back-catalogue with customised printed covers.
Institutional duplication 
Educational, religious, corporate, military, and broadcasting institutions benefited from messaging proliferation through accessibly priced duplicators, offered by Telex Communications, Wollensak, Sony, and others. The duplicators would operate at double (or greater) tape speed. Systems were scalable, enabling the user to purchase initially one "master" unit (typically with 3 "copy" bays) and add "slave" units for expanded duplication abilities.
Data recording 
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, IBM cassette tape was seldom used, as by 1981 floppy drives had become commonplace in high-end machines.
The typical encoding method for computer data was simple FSK, which resulted in data rates of typically 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.
Among home computers that used primarily data cassettes for storage in the late 1970s were Commodore PET (early models of which had a cassette drive built-in), TRS-80 and Apple II, until the introduction of floppy disk drives and hard drives in the early 1980s made cassettes virtually obsolete for day-to-day use in the US. However, they remained in use on some portable systems such as the TRS-80 Model 100 line - often in microcassette form - until the early 1990s. Due to the high price of disks, cassettes also remained the primary data storage medium for 8-bit computers, such as the Commodore 64, ZX Spectrum, MSX and Amstrad CPC 464, in many countries (for example, the UK, where 8-bit software was mostly sold on cassette until that market disappeared altogether in the early 1990s.) Reliability of cassettes for data storage is inconsistent, with gamers recalling repeated attempts to load video games.
In some countries, including the United Kingdom, Poland, Hungary, and the Netherlands, cassette data storage was so popular that some radio stations would broadcast computer programs that listeners could record onto cassette and then load into their computer. See BASICODE.
The use of better modulation techniques, such as 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 (up to 60 MB) and data transfer speeds of 10 to 17 kB/s on each cassette. They found use during the 1980s in data loggers for scientific and industrial equipment.
The cassette was adapted into what is called a streamer cassette, a version dedicated solely for data storage, and used chiefly for hard disk backups and other types of data. Streamer cassettes look almost exactly the same as a standard cassette, with the exception of having a notch about 1/4 inch wide and deep situated slightly off-center at the top edge of the cassette. Streamer cassettes also have a re-usable write-protect tab on only one side of the top edge of the cassette, with the other side of the top edge having either only an open rectangular hole, or no hole at all. This is due to the whole 1/8 inch width of the tape loaded inside being used by a streamer cassette drive for the writing and reading of data, hence only one side of the cassette being used. Streamer cassettes can hold anywhere from 50 to 160 megabytes of data.
Elcaset was a short-lived audio format created by Sony in 1976 that was about twice the size, using larger tape and a higher recording speed. Unlike the original cassette, the Elcaset was designed from the outset for sound quality. It was never widely accepted, as the quality of standard cassette decks rapidly approached high fidelity.
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 format, major companies, such as Sony, shifted their focus to new media. In 1992, Philips introduced the Digital Compact Cassette (DCC), a DAT-like tape in almost the same shell as a Compact 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 failed in both home and mobile environments, and was discontinued in 1996.
The microcassette has in many cases supplanted the full-sized 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. Since the rise of cheap CD-R discs, and flash memory-based digital audio players, the phenomenon of "home taping" has effectively switched to recording to Compact Disc or downloading from commercial or music sharing Web sites.
Because of consumer demand, the cassette has remained influential on design, more than a decade after its decline as a media mainstay. 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 as well, and generally are more reliable than the FM transmitters that must be used to adapt CD players and digital audio players to car stereo systems. Digital audio players shaped as cassettes have also become available, which can be inserted into any cassette player and communicate with the head as if they were normal cassettes.
See also 
- Cassette culture
- Digital cassettes
- Electronic journalism
- List of audio formats
- Magnetic tape data storage
- Magnetic tape sound recording
- Mix tape
- Pocket Rockers
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||This article's use of external links may not follow Wikipedia's policies or guidelines. (November 2012)|
- "Project C-90": Photos of many brands of cassettes
- "Vintage Cassettes": Photos of cassettes gathered in the chronological order
- tapedeck.org: Online collection of audio tape cassettes
- AudioTools: Cassette Tape Reference
- Technical data and photographs of vintage cassette decks
- A brief history of the recording media industry
- Tape recording and playback concepts
- Cassette Tape Sales Rising Again
- Zimbabwe to mass-produce Cassette Tapes to counter piracy
- Audio media evolution history (Spanish)