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| Media type | Magnetic tape cartridge |
|---|---|
| Encoding | Analog signal |
| Read mechanism | Tape head |
| Write mechanism | Magneticrecording head |
| Developed by | Earl Muntz |
| Usage | Car audio playback |
| Released | 1952; 73 years ago (1952) |
TheMuntz Stereo-Pak, commonly known as the4-track cartridge,[1] is amagnetic tape sound recordingcartridge technology.
The Stereo-Pak cartridge was inspired by theFidelipac 2-track monaural (audio & cue tracks, later 3-track for stereo) tape cartridge system invented byGeorge Eash in 1954 and used by radio broadcasters for commercials and jingles in 1959. The Stereo-Pak was adapted from the Fidelipac cartridge design byEarl "Madman" Muntz in 1962, in partnership with Eash, as a way to play pre-recorded tapes in cars.[2][3][4]
The tape is arranged in an infinite loop that traverses a central hub and crosses a tape head, usually under a pressure pad to assure proper tape contact. The tape is pulled by tension, and spooling is aided by a lubricant, usuallygraphite.[5]
Theendless loop tape cartridge was designed in 1952 byBernard Cousino ofToledo, Ohio.[6][7]
Previously, music in the car had been restricted mostly to radios. Records, due to their methods of operation and size, were not practical for use in a car, although several companies tried to market automobile record players such as theHighway Hi-Fi and the Auto-Com flexidisc.[8]
EntrepreneurEarl "Madman" Muntz of Los Angeles, California, saw a potential in Fidelipac broadcast carts for an automobile music tape system, and in 1962 introduced his "Stereo-Pak 4-Track Stereo Tape Cartridge System" and pre-recorded tapes, initially in California and Florida. He licensed popular music albums from the major record companies and duplicated them on these 4-track cartridges, or CARtridges, as they were first advertised.[8]
Music came in four cartridge sizes.
Muntz developed and marketed a variety of mobile and stationary players and recorders for his 4-track tapes.[9]
The B- and C-size carts would have their stereo sound split to mono and be used for background music systems all the way up to the early 1990s, when digital took over. In the last part of that period, a last-ditch effort to reduce cost came in the form of reducing the tape speed first to 1-7/8IPS and then to 15/16 IPS, while reducing the cartridge size first back to the standard widely available A-size and then to a hybrid size between the AA (single) size and the A-size. At first, chromium high-bias tape was used to offset the loss of fidelity from the lower speed, and then, when that proved too expensive, cobalt-based tape was substituted.[citation needed]
After riding in Muntz's car and listening to his 4-track cartridge system, electronics and aerospace entrepreneurBill Lear had an employee ofLear Jet Corporation create a modified derivative, resulting in the more convenient and long-playing8-track cartridge system, which quickly supplanted and surpassed the 4-track in the market until being surpassed, itself, by thecassette tape system.[2]