"RCA Victor tried cutting some 33 1/3 records in the early 30's, but they didn't sound particularly good and could only get about 10 minutes worth of music….so they were quickly withdrawn." ~ OP


You already mention that. Trouble was, not all the parts fit at that time and it flopped.

The first modern LP was announced to the public on either June 20 or 21, 1948 and was exclusive to Columbia.

David Sarnoff of RCA was shown the final product before the public. Thomas Paley of CBS expected Sarnoff to be impressed and sign a licencing agreement and start their own line of LP records on friendly terms.

Instead, Sarnoff thought that Paley was rubbing his nose in it. He left angry and immediatley started his own LP developement unit. It took two years to catch up.

BTW, the term Long Player or LP was copyrighted by Columbia but the production processes were not.