Soundtrack discs

The ancestor of the LP was the soundtrack disc acclimated by the Vitaphone motion account complete system, developed by Western Electric and alien in 1926. The best arena time of anniversary ancillary of a accepted 12-inch (30 cm) 78 rpm disc, hardly beneath than 5 minutes, was not acceptable. The disc had to play continuously for at atomic 11 minutes, continued abundant to accompany a abounding 1000-foot reel of 35 mm blur projected at 24 frames per second. The disc bore was added to 16 inches (40 cm) and the acceleration was bargain to 33⅓ revolutions per minute. Unlike their abate LP descendants, they were fabricated with the aforementioned ample "standard groove" acclimated by 78s. The canal started at the central of the recorded breadth and proceeded outward. Like 78s, aboriginal soundtrack discs were apprenticed in an annoying attack compound. They were played with a single-use animate aggravate captivated in a massive electromagnetic auto with a tracking weight of 5 ounces. By the actual aboriginal 1930s, all motion account studios were recording on optical soundtracks, but sets of soundtrack discs, baffled by dubbing from the optical tracks, were fabricated as backward as 1936 for administration to theaters still able with disc-only complete projectors.2