Media type | Audio playback |
---|---|
Encoding | Analog groove modulation |
Capacity | Originally 23 minutes per side, later increased by several minutes, much longer possible with very low signal level |
Read mechanism | Microgroove stylus (maximum tip radius 0.001 in or 25 μm) |
Developed by | Columbia Records |
Dimensions | 12 inches (30 cm), 10 inches (25 cm), 90–240 g (3.2–8.5 oz) |
Usage | Audio storage |
Released | 1948 |
The LP (from long playing[1] or long play) is an analog sound storage medium, specifically 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. Introduced by Columbia Records in 1948, it was soon adopted as a new standard by the entire US record industry and, apart from a few relatively minor refinements and the important later addition of stereophonic sound in 1957,[2] it remained the standard format for record albums during a period in popular music known as the album era.[3] LP was originally a trademark of Columbia[4] and competed against the smaller 7-inch sized "45" or "single" format by RCA Victor, eventually ending up on top.[5] Today in the vinyl revival era, a large majority of records are based on the LP format and hence the LP name continues to be in use today to refer to new records.[6][7]
LP - Exclusive trade mark of Columbia Records Inc.