LP album
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Long playing (LP) record albums are either 10 or 12-inch diameter, 33-1/3 rpm vinyl phonograph records. They were first introduced in 1948 and served as the primary release format for recorded music until Compact Discs (CDs) began to significantly displace them in the 1980s.
The long-playing record is an analog format. The digital recording of sound was only made practical by the technical advances in microprocessors and computing which occurred in the 1970s and 1980s.
Between 1948 and 1955, the majority of LPs were 10 in. (25 cm) in diameter, matching that of 78 rpm singles. The diameter was eventually increased to 12 in. (30 cm), matching higher-priced classical 78s, and 10 in. records were relegated to the status of EPs (extended play). When initially introduced, LPs played for a maximum of 45 minutes, divided over two sides. However, in 1952, Columbia Records began to bring out "extended play" LPs that played for as long as 52 minutes, or 26 minutes per side. These were used mainly for the original cast albums of some Broadway musicals, such as Kiss Me, Kate and My Fair Lady, or in order to fit an entire play, such as the 1950 production of Don Juan in Hell, onto just two LPs. The 52+ minute playing time remained rare, however, due to mastering limitations, and most LPs continued to be issued with a 30- to 45-minute playing time throughout the lifetime of their production.
Even so, the 45-minute play time of the LP was a significant improvement over the previous dominant format, the 45 rpm single, which was generally limited to 3- to 5-minutes. At around 15–20 minutes per side, LPs provided a measured time to enjoy a recording before having to flip discs. Incidentally, having both an A-side and a B-side (unlike the first 78s) also gave users the option to continue playing the other side of the album.
Some record turntables, called record changers, could play a "stack" of records piled on a specially-designed spindle and arm arrangement. Because of this, many multiple-record sets were released in what's called "automatic sequence." A two-record set would have Side 1 and Side 4 on one record, and Side 2 and Side 3 on the other, so that the first two sides could play in a changer without the listener's intervention, and then they could simply flip the stack over. Larger boxed sets used appropriate automatic sequencing (1+8, 2+7, 3+6, 4+5 for example) leading to a sometimes-bewildering search.
In contrast to today's CD players, very few record players (e.g., laser turntables) could provide a per-track programmable interface, so the record albums play in the same order every time. As the LP achieved market dominance, musicians and producers began to pay special attention to the flow from song-to-song, to keep a consistent mood or feel, or to provide thematic continuity, as in concept albums.
Records are susceptible to damage from mishandling: Dropping the record or contact with its exposed surface could easily result in scratches. This would cause a "tick" sound every revolution on playback, if it did not abort playback of one or more tracks entirely, due to physical mis-tracking of the record player stylus, a sapphire or diamond needle which tracked the groove. The large surface area of the record, being vinyl and therefore statically charged, would pull dust and smoke suspended particles out of the air, also causing ticks, pops and (in worst cases of contamination) distortion during playback. Therefore, audiophiles would commonly clean the record surface carefully before playing, using an appropriate record cleaner and/or some antistatic record cleaning fluid. [1]
LP discs being delicate, as well as deceptively heavy for their size, people were less inclined to lug the significant weight of a stack of them around, for example, when visiting friends or when traveling, than a similar quantity of music compiled onto 90-minute cassettes compilation-tapes or in comparison with today's digital formats.
The average LP had about 1,600 feet of groove on each side, or about a third of a mile. The needle travels approximately 1 mph on average. It travels fastest on the outside edge, unlike CDs, which change their speed of rotation to provide constant linear velocity. (Also, CDs play from the inner radius outward, the reverse of phonograph records.)
The RIAA equalization curve (used since 1954) provides a de-emphasis in the bass notes, allowing closer spacing of record grooves and hence more playing time. Turntable cartridge preamplifiers reverse the RIAA curve to flatten out the frequencies again.
Disc jockeys (or DJs) still rely heavily on vinyl records, as there is no efficient way to cue tracks from cassette tapes and CDs do not allow creative playback options. The term "DJ" has come to encompass all kinds of skills in "scratching" (record playback manipulation) and mixing dance music, rapping over the music or even playing musical instruments, but the original definition was simply somebody who played records (LP tracks or 12" singles) in a club, alternating between two turntables. The skill came in subtly matching beats or instruments from one song-to-the-next, providing a consistent dance floor tempo. DJs also made occasional announcements and chatted with patrons to take requests while songs were actually playing.
The audio quality of LPs increased greatly over time, and a small contingent of analog fans still maintain they are superior to digital media. Early LP recordings were monaural, but stereo LP records became commercially available in 1957. In the 1970s, quadraphonic sound (4-channel) records became available. These did not achieve the popularity of stereo records, partly due to scarcity of consumer playback equipment and partly due to the lack of quality in quad-remix releases. Quad never escaped the reputation of being a "gimmick".
Besides the standard black vinyl, specialty records were also pressed on different colors of PVC (red, yellow, green, blue, white, clear, pink, multi-color and more) or special "picture discs" with a cardboard picture sandwiched between two clear sides. Records in different novelty shapes were also produced.
Although most LPs played at 33-1/3 rpm, some "super fidelity" discs were designed to play at 45 rpm. There were also, early in the evolution of the LP, some records (primarily spoken word) designed to play at 16-2/3 rpm, though players were rare.
The composition of vinyl used to press records varied considerably over the years. Virgin vinyl is preferred, but during the petrochemical crisis on the late 1970s it became commonplace to use recycled vinyl, melted unsold records with all the impurities. Sound quality suffered, with increased ticks, pops and other surface noises. Other experiments included reducing the thickness of LPs, leading to inherent warpage or increased susceptibility to damage. Using a bead of 130 grams of vinyl had been the standard, but some labels experimented with as little as 90 grams per LP. Today, high fidelity pressings follow the Japanese standard of 160, 180 or 200 grams.