Today’s quiz is about physical audio platters(records), their rpm speeds & sizes
Background: In the golden age of physical audio records, certain rpm speeds became the industry standards after the famous “War of the Speeds” in 1948–1949 between Columbia records and RCA. By the 1960s, nearly every consumer record player (turntable/phonograph) included a speed selector knob with these rpm speed options to play the full range of formats.
Question: What were the main RPM speeds that emerged as standards and what were the platter sizes?
Answer: 33⅓ RPM, 45 RPM, and 78 RPM emerged as the standard on newer record players. The most common platter sizes (diameters) associated with these standards are:
78 RPM → 10-inch (most common; some 12-inch for longer classical pieces, but 10″ was the everyday standard for pop and shellac records)
33⅓ RPM → 12-inch (the classic LP album size; 10-inch was used early on for shorter albums, but 12″ became dominant)
45 RPM → 7-inch (the iconic single with the big center hole for jukeboxes and auto-changers)
The Winners
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KF4XD
VE3BW
AA4E
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KE4SKA
W4HI
Thanks for participating in the May 30th Net!
Ron / K4RJT