Cassette tape

The Compact Cassette or Musicassette (MC), also commonly called the tape cassette, cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. It was developed by the Dutch company Royal Philips in Hasselt, Belgium, by Lou Ottens and his team. It was introduced in September 1963. Compact Cassettes come in two forms, either already containing content as a prerecorded cassette (Musicassette), or as a fully recordable "blank" cassette. Both forms have two sides and are reversible by the user.
The compact cassette technology was originally designed 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. The first cassette player (although mono) designed for use in car dashboards was introduced in 1968. From the early 1970s to mid-2000s, the cassette was one of the two most common formats for prerecorded music, first alongside the LP record and later the compact disc (CD).
Compact Cassettes contain two miniature spools, between which the magnetically coated, polyester-type plastic film (magnetic tape) is passed and wound. These spools and their attendant parts are held inside a protective plastic shell which is at its largest dimensions. The tape itself is commonly referred to as "eighth-inch" tape, supposedly wide, but it is slightly larger: . 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 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 flipping the cassette, or by the reversal of tape movement ("auto-reverse") when the mechanism detects that the tape has come to an end.
History.
Before the Compact Cassette.
In 1935, AEG released the first reel-to-reel tape recorder with the commercial name "Magnetophon". It was based on the invention of the magnetic tape by Fritz Pfleumer in 1928. These machines were very expensive and relatively difficult to use and were therefore used mostly by professionals in radio stations and recording studios.
After the Second World War, the magnetic tape recording technology proliferated across the world. In the U.S., Ampex, using equipment obtained in Germany as a starting point, began commercial production of tape recorders. First used in studios to record radio programs, tape recorders quickly found their way into schools and homes. By 1953, 1 million U.S. homes had tape machines. 
In 1958, following four years of development, RCA Victor introduced the stereo, quarter-inch, reversible, reel-to-reel RCA tape cartridge. The cartridge was large (5 × 7 in, or 13 × 20 cm), and few pre-recorded tapes were offered. Despite the multiple versions, it failed.
Consumer use of magnetic tape machines took off in the early 1960s, after playback machines reached a comfortable, user-friendly design. This was aided by the introduction of transistors which replaced the bulky, fragile, and costly vacuum tubes of earlier designs. Reel-to-reel tape then became more suitable for household use, but still remained an esoteric product.
Introduction of the Compact Cassette.
In the early 1960s Philips Eindhoven tasked two different teams to design a tape cartridge for thinner and narrower tape compared to what was used in reel-to-reel tape recorders. By 1962, the Vienna division of Philips developed a single-hole cassette, adapted from its German described name "Einloch-Kassette". The Belgian team created a two-spool cartridge similar to an earlier RCA design, but much smaller. 
Philips selected the two-spool cartridge as a winner and introduced it in Europe on 30 August 1963 at the Berlin Radio Show, and in the United States (under the "Norelco" brand) in November 1964. The trademark name "Compact Cassette" came a year later. The team of Dutch and Belgian origin at Philips was led by the Dutch Lou Ottens in Hasselt, Belgium.
Philips also offered a machine to play and record the cassettes, the Philips "Typ EL 3300". An updated model, "Typ EL 3301" was offered in the U.S. in November 1964 as Norelco "Carry-Corder 150". 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. By the end of the 1960s, the cassette business was worth an estimated 150 million dollars. By the early 1970s the compact cassette machines were outselling other types of tape machines by a large margin.
Philips was competing with Telefunken and Grundig (with their DC International format ) in a race to establish its cassette tape as the worldwide standard, and it wanted support from Japanese electronics manufacturers. Philips' Compact Cassette became dominant as a result of Sony pressuring Philips to license the format to them free of charge.
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.
Popularity of music cassettes.
The mass production of "blank" (not yet recorded) Compact Cassettes began in 1964 in Hanover, Germany. Prerecorded music cassettes (also known as "Music-Cassettes", and later just Musicassettes; M.C. for short) were launched in Europe in late 1965. The Mercury Record Company, a US affiliate of Philips, introduced M.C. to the US 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 an unreliable mechanical design. In 1971, the Advent Corporation introduced their Model 201 tape deck that combined Dolby type B noise reduction and chromium(IV) oxide (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.
Although the birth and growth of the cassette began in the 1960s, its cultural moment took place during the 1970s and 1980s. The cassette's popularity grew during these years as a result of being a more effective, convenient and portable way of listening to music. Stereo tape decks and boom boxes became some of the most highly sought-after consumer products of both decades. Portable pocket recorders and high-fidelity ("hi-fi") players, such as Sony's Walkman (1979), also enabled users to take their music with them anywhere with ease. The increasing user-friendliness of the cassette led to its popularity around the globe.
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 for the decade of the '80s, 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. Another barrier to cassettes overtaking vinyl in sales was shoplifting; compact cassettes were small enough that a thief could easily place one inside a pocket and walk out of a shop without being noticed. To prevent this, retailers would place cassettes inside oversized "spaghetti box" containers or locked display cases, either of which would significantly inhibit browsing, thus reducing cassette sales. During the early 1980s some record labels sought to solve this problem by introducing new, larger packages for cassettes which would allow them to be displayed alongside vinyl records and compact discs, or giving them a further market advantage over vinyl by adding bonus tracks. Willem Andriessen wrote that the development in technology allowed "hardware designers to discover and satisfy one of the collective desires of human beings all over the world, independent of region, climate, religion, culture, race, sex, age and education: the desire to enjoy music at any time, at any place, in any desired sound quality and almost at any wanted price". Critic Robert Palmer, writing in "The New York Times" in 1981, cited the proliferation of personal stereos as well as extra tracks not available on LP as reasons for the surge in popularity of cassettes.
Between 1985 and 1992, the cassette tape was the most popular format in the UK and record labels experimented with innovative packaging designs. A designer during the era explained: "There was so much money in the industry at the time, we could try anything with design." The introduction of the cassette single, called a "cassingle", was also part of this era and featured a music single in Compact Cassette form. Until 2005, cassettes remained the dominant medium for purchasing and listening to music in some developing countries, but compact disc (CD) technology had superseded the Compact Cassette in the vast majority of music markets throughout the world by this time.
Cassette culture.
Compact cassettes served as catalysts for social change. Their small size, 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. During the military dictatorship of Chile (1973–1990) a "cassette culture" emerged where blacklisted music or music that was by other reasons not available as records was shared. Some pirate cassette producers created brands such as "Cumbre y Cuatro" that have in retrospect received praise for their contributions to popular music. Armed groups such as Manuel Rodríguez Patriotic Front (FPMR) and the Revolutionary Left Movement (MIR) made use of cassettes to propagandize their struggle.
In 1970s India, cassettes 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. Some sales channels were associated with cassettes: in Spain filling stations often featured a display selling cassettes.
While offering also mainstream music these cassettes became associated with genres such as Gipsy rhumba, light music and joke tapes that were very popular in the 1970s and 1980s.
Decline.
Cassettes remained popular for specific applications, such as car audio, personal stereo and telephone answering machines, well into the 1990s. Cassettes players were typically more resistant to shocks than CD players, and their lower fidelity was not considered a serious drawback. With the introduction of electronic skip protection it became possible to use portable CD players on the go, and automotive CD players became viable.
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. By the early 2000s, the CD player rapidly replaced the cassette player as the default audio component in the majority of new vehicles in Europe and America.
Sales of pre-recorded music cassettes in the U.S. dropped from 442 million in 1990 to 274,000 by 2007. Most of the major U.S. music companies had discontinued production of pre-recorded cassettes by 2003.
For audiobooks, the final year that cassettes represented greater than 50% of total market sales was 2002 when they were replaced by CDs as the dominant media. Many out of print titles, such as those published during the cassette's heyday of the 1970s-2000s, are only available on the original cassettes.
The last new car with an available cassette player was a 2010 Lexus SC 430. The same year Sony stopped the production of personal cassette players. In 2011, the Oxford English Dictionary removed the word "cassette player" from its 12th edition Concise version. Some media sources mistakenly claimed that the term "cassette tape" was being removed.
21st-century use and revival.
Although portable digital recorders are most common today, analog tape remains a desirable option for certain artists and consumers. Older genres like "dansband" may favor the format most familiar to their fans. Some musicians and DJs in the independent music community maintain a tradition of using and releasing cassettes due to its low cost and ease of use. 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. Even among major label stars, the form has at least one devotee: Thurston Moore claimed in 2009, "I only listen to cassettes." Very few companies (as of 2021) still make cassettes. Among those are National Audio Company, from the US, and Mulann, also known as Recording The Masters, from France. They both make their own magnetic tape, which used to be outsourced.
In 2010, Botswana-based Diamond Studios announced plans for establishing a plant to mass-produce cassettes in a bid to combat piracy. It opened in 2011.
In South Korea, the early English education boom for toddlers encourages a continuous demand for English language cassettes, , due to the affordable cost.
In India, film and devotional music continued to be released in the cassette format due to its low cost until 2009.
National Audio Company in Missouri, the largest of the few remaining manufacturers of audiocassettes in the U.S., oversaw the mass production of the "Awesome Mix #1" cassette from the film "Guardians of the Galaxy" in 2014.
They reported that they had produced more than 10 million tapes in 2014 and that sales were up 20 percent the following year, their best year since they opened in 1969. In 2016, cassette sales in the United States rose by 74% to 129,000. In 2018, following several years of shortage, National Audio Company began producing their own magnetic tape, becoming the world's first known manufacturer of an all-new tape stock. Mulann, a company which acquired Pyral/RMGI in 2015 and originates from BASF, also started production of its new cassette tape stock in 2018, basing on reel tape formula.
In Japan and South Korea, the pop acts Matsuda Seiko, SHINee, and NCT 127 have released their recent material on limited-run cassettes.
In 2016, retail chain Urban Outfitters, which had long sold LPs, started selling new pre-recorded cassettes (both new and old albums), blank cassettes, and players.
Some synthwave artists, such as The Midnight, Michael Oakley, and Anders Enger Jensen, have released their albums on cassette, in addition to digital downloads. Some tracks in this genre, such as The Midnight's "Endless Summer" and "Memories", LeBrock's "Please Don't Cry", and Michael Oakley's "Rabbit in the Headlights", include sound effects at the beginning or end of the track that are reminiscent of cassette listening even when another medium is used.
Since 2016, cassette sales have seen a modest resurgence, with 2016, 2017, and 2018 all showing increases.
In 2019 musical artist Madonna, known as "The Queen of Pop", released her acclaimed 14th album Madame X in a classic cassette tape version.
Features.
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 wide, with each mono track wide, plus an unrecorded guard band between each track. In stereo, each track is further divided into a left and a right channel of each, with a gap of . The tape moves past the playback head at , the speed being a continuation of the increasingly slower speed series in open-reel machines operating at 30, 15, , or inches per second. For comparison, the typical open-reel -inch 4-track consumer format used tape that is wide, each track 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.
In 1968 DuPont, the inventor of chromium dioxide (CrO2) manufacturing process, began commercialization of CrO2 media. The first CrO2 cassette was introduced in 1970 by Advent, and later strongly backed by BASF, the inventor and longtime manufacturer of magnetic recording tape. Next, coatings using magnetite (Fe3O4) such as TDK's Audua were produced in an attempt to approach or exceed the sound quality of vinyl records. Cobalt-"adsorbed" iron oxide (Avilyn) was introduced by TDK in 1974 and proved very successful. "Type IV" tapes using 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 and earlier cassette decks are designed to work with standard ferric formulations. Newer tape decks usually are built with switches and later detectors for the different bias and equalization requirements for higher grade tapes. The most common, iron oxide tapes (defined by the IEC 60094 standard, as "Type I") use 120 µs equalization, while chrome and cobalt-adsorbed tapes (IEC Type II) require 70 µs equalization. The recording bias levels also were different. 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. These also use 70 µs, just like Type II did. 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. 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 near the middle of the top of the cassette shell. These allow later cassette decks to detect the tape type automatically and select the proper bias and equalization.
An exception to this standard were mechanical storytelling dolls from the 1980s (e.g. Teddy Ruxpin) which used the Type IV metal configuration cassette shell but had normal Type I voice grade tape inside. These toys used the Type IV notches to detect that a specially coded tape had been inserted, where the audio of the story is stored on the left channel and various cue tones to tell the doll's servos how and when to move along with the story on the right channel.
Most pre-recorded chrome cassettes require 120 µs equalisation and are treated as Type I (with notches as Type I ferric cassettes), to ensure compatibility with budget equipment.
Tape length.
Tape length usually is measured in minutes of total playing time. The most popular varieties (sometimes sold with a capital letter "C" prefixed) are C46 (23 minutes per side), C60 (30 minutes per side), C90, and C120. The C46 and C60 lengths typically are thick, but C90s are and (the less common) C120s are just thick, rendering them more susceptible to stretching or breakage. 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 were in past available from Maxell (UR 150), Sony (CDixI 150) and TDK (TDK AE 150, CDing1 150 and CDing2 150), only in Japan. All of these were discontinued - Maxell simplified its cassette offer to 10, 20, 60 and 90-minute lengths, Sony exited the audio cassette market globally, and Imation, licensee of the TDK trademark, exited the consumer products market.
Other lengths are (or were) also available from some vendors, including C10, C12 and C15 (useful for saving data from early home computers and in telephone answering machines), C30, C40, C50, C54, C64, C70, C74, C80, C84, C94, 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.
Most manufacturers load more tape that a label indicates, for example rather than of tape for a C60 cassette, and rather than of tape for a C90 cassette, providing an extra minute or two of playback time per side.
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.
Track width.
The full tape width is 3.8 mm. For mono recording the track width is 1.5 mm. In stereo mode each channel has width of 0.6 mm with a 0.3 mm separation to avoid crosstalk.
Head gap.
The head gap of a tape recorder is the space, along the tape path, between the ends of the pole pieces of the head. Without a gap. the head would produce a "closed" magnetic field and would not interact enough with the magnetic domains on the tape.
The head-gap width is 2 µm which gives a theoretical maximum frequency of about 12 kHz (at the standard speed of 1 7/8 ips or 4.76 cm/s). A narrower gap would give a higher frequency limit but also weaker magnetization. However, such limitations can be corrected through equalization in the recording and playback amplification sections, and narrower gaps were quite common, particularly in more expensive cassette machines. For example, the RP-2 series combined record/playback head (used in many Nakamichi cassette decks from the 1980s and 1990s) had a 1.2 µm gap, which allows for a playback frequency range of up to 20 kHz. A narrower gap width makes it harder to magnetize the tape, but is less important to the frequency range during recording than during playback, so a two-head solution can be applied: a dedicated recording head with a wide gap allowing effective magnetization of the tape and a dedicated playback head with a specific width narrow gap, possibly facilitating very high playback frequency ranges well above 20 kHz.
Separate record and playback heads were already a standard feature of more expensive reel-to-reel tape machines when cassettes were introduced, but their application to cassette recorders had to wait until demand developed for higher quality reproduction, and for sufficiently small heads to be produced.
Write-protection.
Most cassettes include a write protection mechanism to prevent re-recording and accidental erasure of important material. There are two indentations on the top of a cassette corresponding to each side of the cassette. On blank cassettes these indentations are protected with plastic tabs that can be broken off to prevent recording on the corresponding side of the cassette. Occasionally and usually on higher-priced cassettes, manufacturers provided a movable panel that could be used to enable or disable write-protect on tapes. Pre-recorded cassettes do not have protective tabs, leaving the indentations open.
If later required, the cassette can be made recordable again by either covering the indentation with a piece of adhesive tape or by putting some filler material into the indentation. On some decks, the write-protect sensing lever can be manually depressed to allow recording 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 is attached to each spool with a leader, usually made of strong plastic. This leader protects the weaker magnetic tape from the shock occurring when the tape reaches the end. Some leaders are designed to clean the magnetic heads each time the tape is played. Leader also enables to record over an existing recording cleanly, without a blip of sound that otherwise would be left from the previous recording.
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 is that the sound recording or playback does 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 are made, typically with stronger material and for use in machines that had more sophisticated end-of-tape prediction. Home computers that made use of cassettes as a more affordable alternative to floppy discs (e.g. Apple II, Commodore PET) were designed to not start writing or reading data until leaders had spooled past.
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. One variant has a half-width loop of tape for an answering machine outgoing message, and another half-width tape on spools to record incoming messages.
Cassette tape adapter.
Cassette tape adapters allow external audio sources to be played back from any tape player, but were typically used for car audio systems. An attached audio cable with a phone connector converts the electrical signals to be read by the tape head, while mechanical gears simulate reel to reel movement without actual tapes when driven by the player mechanism.
Optional mechanics.
In order to wind up the tape more reliably, the former BASF (from 1998 EMTEC) patented the Special Mechanism or Security Mechanism advertised with the abbreviation SM in the early 1970s, which was temporarily taken over by Agfa under license. This feature each includes a rail to guide the tape to the spool and prevent an unclean roll from forming.
The competition responded by inserting additional deflector pins closer to the coils in the lower plastic case half. Some low-priced and pre-recorded compact cassettes were made without pulleys; the tape is pulled directly over the capstan drive. For the pressure of the tape to the head there is a thinner felt on a glued foam block instead of the usual felt on a leaf spring.
Flaws.
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. Wow and Flutter, however, can sometimes be added intentionally to recordings for aesthetic reasons. (See Lo-fi music)
A common mechanical problem occurred when a defective player or resistance in the tape path causes a failure to keep sufficient tension on the take-up spool. 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" or "chewed" the tape, often destroying the playability of the cassette.<ref>