Unless the quantity required was very small, pressed discs were a more economical medium for distributing high-quality audio than tape, and CD mastering was, in the early years of that technology, very expensive, so the use of LP-format transcription discs continued into the 1990s. History īy mid-1931 all motion picture studios were recording on optical soundtracks, but sets of soundtrack discs, mastered by dubbing from the optical tracks and scaled down to 12 inches to cut costs, were made as late as 1936 for distribution to theaters still equipped with disc-only sound projectors. Each side of a 12-inch LP could play for about 22 minutes. The new product was a 12- or 10-inch (30 or 25 cm) fine-grooved disc made of PVC ("vinyl") and played with a smaller-tipped "microgroove" stylus at a speed of 33 + 1⁄ 3 rpm. Format advantages Īt the time the LP was introduced, nearly all phonograph records for home use were made of an abrasive (and therefore noisy) shellac compound, employed a much larger groove, and played at approximately 78 revolutions per minute (rpm), limiting the playing time of a 12-inch diameter record to less than five minutes per side. Apart from a few relatively minor refinements and the important later addition of stereophonic sound, it remained the standard format for record albums (during a period in popular music known as the album era) until its gradual replacement from the 1980s to the early 2000s, first by cassettes, then by compact discs, and finally by digital music distribution.īeginning in the late 2000s, the LP has experienced a resurgence in popularity. Introduced by Columbia in 1948, it was soon adopted as a new standard by the entire record industry. The LP (from "long playing" or "long play") is an analog sound storage medium, a phonograph record format characterized by: a speed of 33 + 1⁄ 3 rpm a 12- or 10-inch (30- or 25-cm) diameter use of the "microgroove" groove specification and a vinyl (a copolymer of vinyl chloride acetate) composition disk. Originally 23 minutes per side, later increased by several minutes, much longer possible with very low signal level
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