08-28-2021, 07:26 PM
Ah, but 33-1/3 rpm records had already been developed for the Vitaphone system in 1927! Those early 33-1/3 rpm records were not microgroove as were the postwar Columbia LP records, and soon disappeared once sound-on-film techniques were perfected.
https://www.history-of-rock.com/record_formats.htm
https://www.history-of-rock.com/record_formats.htm
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Ron Ramirez
Ferdinand IN