78 rpm record

78 rpm recording time

The playing time of a phonograph record is directly proportional to the available groove length divided by the turntable speed. Total groove length in turn depends on how closely the grooves are spaced, in addition to the record diameter. At the beginning of the 20th century, the early 7-inch (180 mm) discs played for two minutes, the same as cylinder records. The 10-inch (250 mm) disc, introduced by Victor in January 1901, increased the playing time to three and a half minutes. The short-lived 14-inch (360 mm) record was introduced by Victor in the spring of 1903, the 12-inch (300 mm) disc in the summer of 1903 and the 8-inch (200 mm) disc in 1906, all increasing the playing time and fidelity over the 7-inch (180 mm) format. Even before the introduction of 14-inch (360 mm), 12-inch (300 mm) and 8-inch (200 mm) the10-inch (250 mm) rapidly overtook sales of the 7-inch (180 mm). Because the standard 10-inch (250 mm) 78 rpm record could hold about 3.5 minutes of sound per side, most popular recordings were limited to that duration. For example, when King Oliver's Creole Jazz Band, including Louis Armstrong on his first recordings, recorded 13 sides at Gennett Records in Richmond, Indiana, in 1923, one side was 2:09 and four sides were 2:52–2:59.