12-inch single

The 12-inch [30 cm] single gramophone record came into existence with the advent of disco music in the 1970s. The first 12" single was actually a 10" acetate used by a mix engineer (Jose Rodriquez) in need of a Friday night test copy for famed disco mixer Tom Moulton. As no 7" acetates could be found, a 10" blank was used. Mr. Moulton, feeling silly with a large disc that only had a few centimeters of groove on it, asked Rodriguez to re-cut it so the grooves looked more spread out. Because of the wider spacing of the grooves, a broader overall dynamic range (distinction between loud and soft) was made possible. This was immediately noticed to give a more favorable sound for discotheque play.
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