Philips Compact Cassette

A cartridge measured against a coat pocket

The Compact Cassette was introduced in Europe on 28 August 1963 at the Berlin Radio Show, the Funkausstellung, as a two-track, two-direction mono format. Philips built the recorder that went with it, the Typ EL 3300, and shipped an updated machine to the United States in November 1964 under the Norelco brand as the Carry-Corder 150.

The project belonged to Lou Ottens, who had been put in charge of new product development at Philips in the early 1960s. His team worked at Hasselt and called the design the Pocket Recorder. Ottens kept a pocket-sized block of wood on his desk as the target, and the finished shell stayed close to it: about 10.2 by 6.35 by 1.27 centimetres at its largest dimensions, a plastic box small enough for a jacket pocket.

That constraint decided the rest. Two reels had to fit a shell that size, so the tape was narrow, the spools small, and the tape ran slowly with less magnetic material than the open-reel machines it came from. The cassette did not invent tape recording; it miniaturised it and sealed it in a cartridge that needed no threading.

The numbers that became the standard

The tape inside is 3.81 millimetres wide, slightly more than the eighth of an inch the trade usually quoted. In mono, each track is 1.5 millimetres wide with an unrecorded guard band between them. In stereo, each track splits into a left and right channel of 0.6 millimetres, separated by a 0.3 millimetre gap. The tape crosses the head at 4.76 centimetres per second, or 1 7/8 inches per second, the next step below the slowest open-reel speed.

Those dimensions became a global contract: the same openings, hubs and head window on every shell, so any cassette would play in any machine built to the standard. Philips settled on the familiar lengths of 30, 45 and 60 minutes per side, sold as C60, C90 and C120.

Two design teams and a rival format

Inside Philips the brief went to two groups. A team in Vienna, which knew dictation machines, developed a single-hole cassette with Grundig, the Einloch-Kassette. The Hasselt team under Ottens built the two-hole two-spool design, and Philips chose it. Grundig answered with its own DC-International format, drawn from the Compact Cassette and launched in 1965.

The rivalry ended in Philips' favour, and not only on engineering. Philips licensed the patented format freely to other manufacturers from 1966, and later gave way to pressure from Sony for a free licence, which let cassette production spread across Japan and Europe faster than one company could have managed. The DC-International was discontinued in 1967, two years after it arrived.

From dictation to high fidelity

Pre-recorded Musicassettes arrived in Europe in late 1965. The Mercury Record Company, a Philips affiliate in the United States, brought them to America in July 1966 with 49 titles, and British labels followed in October 1967. None of this made the cassette sound good: early players were built for speech, and narrow tracks at slow speed produced audible hiss.

The turning point was hardware. In 1971 the Advent Corporation introduced its Model 201 deck, combining Dolby B noise reduction with chromium dioxide tape and a commercial transport mechanism from 3M's Wollensak division. Dolby B became common through the middle of the decade, cutting the hiss enough for the cassette to be taken seriously as a music carrier. Better tape followed: chromium dioxide media in 1970, TDK's cobalt-doped Avilyn in 1974, and pure metal particle tape from 3M in 1979.

The format that outsold the record

The Sony Walkman TPS-L2 went on sale on 1 July 1979, and the cassette became the soundtrack of the following decade. Cassettes accounted for 4.6 per cent of American music sales in 1973, outsold eight-track tapes for the first time in 1980, and outsold LPs for the first time in 1984. According to RIAA figures, the format held at least half the American market from 1984 to 1989, and it was the most popular format for new music sales in the United States from 1983 to 1991.

Ottens was clear-eyed. "We expected that it would be a success but not a revolution," he said in the 2016 documentary Cassette: A Documentary Mixtape. An estimated 100 billion cassettes were sold worldwide.

The cheap blank tape changed behaviour as much as the hardware did. Home taping let a listener assemble a running order, copy a friend's record and hand the result on, and the record industry spent the late 1970s complaining about it. The same property made the cassette political: dubs carried banned music behind the Iron Curtain and through Chile under military rule, and sermons by the exiled Ayatollah Khomeini circulated on tape before the 1979 Iranian revolution.

A second life as computer storage

Cheap, rewritable and standardised, the cassette became the default storage for 8-bit home computers, including the Commodore 64, ZX Spectrum, MSX and Amstrad CPC 464. In Britain most 8-bit software was sold on cassette until that market disappeared in the early 1990s, and some radio stations broadcast programs as audio that listeners recorded and loaded.

The decline was gradual. CDs overtook pre-recorded cassettes in the United States in the early 1990s, though cassettes held on in cars and answering machines. American sales of pre-recorded cassettes fell from 442 million in 1990 to 274,000 in 2007. Sony stopped making personal cassette players in 2010, and the last new car offered with a cassette deck was a 2014 TagAZ AQUILA. A small manufacturing base survives for DIY releases, which is roughly where the cassette sits now: obsolete as a mass format, still in use by choice.