 "Your Steps To Music" |
About 45 RPM RecordsThe 45 RPM record was developed by RCA Victor company in 1948 - immediately following the invention of "vinyl" plastic and the development of the 12" LP record by CBS engineers (also in 1948). The 45 RPM speed was the only one to be decided by a precise optimization procedure. Calculus was used to show that the optimum use of a disc record of constant rotational speed occurs when the innermost recorded diameter is half the outermost recorded diameter. That's why a 7-inch single has a label 3 1/2 inches in diameter. Given the CBS LP vinyl groove dimensions and certain assumptions about the bandwidth and tolerable distortion, a speed of 45 rpm comes out of the formula. (Peter Copeland, British Library National Sound Archive, London). RCA 45 RPM Player (about 1950) To market their format against the currently "reigning" 78 RPM (and the CBS 12" LP) RCA released a series very low priced 45 RPM only players in the late 1940s and early 1950s. Both amplified & non amplified models were manufactured. The player above was sold in the early 1950s and was equipped with a ceramic cartridge and an "RCA" jack - also "invented" at the time! The model above did not include an amplifier or speaker but was meant to plugged into the corresponding female RCA jack in an RCA radio or TV - and use that product's amplifier and speaker. If you're aged 50 or older, you may remember quite a number of these players by 1955 - sitting atop TV sets! In spite of the popularity of LPs, the sales of 45 RPM records continued to increase all through the 1950s, 1960s and 1970s. In their "peak" sales years from 1973 to 1976 more than 100 million were sold each year in the USA. 45s made since 1971 are in stereo and have the same fidelity output as CDs - i.e., 20 Hz to 20,000 Hz - a credit to the RCA engineers more than 50 years ago! Both "oldie" and "newie" 45 RPM records are still being manufactured today. More than 2 million were pressed in 1998! (Neil Patte, 1999) |
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