This inadequacy generated the recognition of record players which developed into record players that change records that increased in popularity. Records of 33 1/2 rpm were developed in conjunction with films. A 12-inch 78 with Berliner-type grooves could hold between 4 and 5 minutes per side. A reel of film might run for 11 minutes, so a rotational speed of about 32 rpm was required to make the sound match the picture. They then a new groove dimensions was developed which gave an acceptable signal-to-noise ratio with the new plastic material vinyl in the late 1920s had their sound on separate disc records and it was more important for the sound to be continuous. A reel of film might run for 11 minutes, so a rotational speed of about 32 rpm was required to make the sound match the picture. History doesn't tell us why precisely 33 1/3 was chosen. It appeared that CBS engineers developed the first LPs in 1948 by simply experimenting with old machines that was lying around in their workshop. They then developed new groove dimensions which gave an acceptable signal-to-noise ratio with the new plastic material; the vinyl. The 45 rpm speed was the only one to be decided by a precise optimal procedure by RCA Victor in 1948. Calculus was used to show that the optimum use of a disc record was of constant rotational speed. his occurs when the innermost recorded diameter is half the outermost recorded diameter. That's why a 7-inch single has a label 31/2 inches in diameter. Given the CBS vinyl groove dimensions and certain supposition about the bandwidth and tolerable distortion, a speed of 45 rpm came out of the formula. From 1894 to 1930, there were many different recording speeds ranging from 65 to 90 rpm. | 
