Where does this come from, and can I check it?

The 1949 format had a wide centre hole so automatic changers could grip it. The figure is taken from Library of Congress, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a music fact?

Yes. It sits on the Music shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

RCA's seven-inch single spun at 45 rpm

The 1949 format had a wide centre hole so automatic changers could grip it RCA Victor launched the 45 in 1949 as a rival to Columbia's long-playing disc, pressing it in bright coloured vinyl at first. The oversized hole let a changer's spindle mechanism drop each record cleanly. The format outlasted the changers, and a plastic spider soon let it play on ordinary turntables. It sits in Mondo's music collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Library of Congress

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Technology trivia

More facts like this

The long playing record arrived in 1948Columbia's microgroove LP turned at 33 and a third and held about 22 minutes a side Records outsold compact discs againVinyl passed CD revenue in the late 2010s and kept climbing One side of an LP holds hundreds of metres of grooveThe spiral on a twelve inch record unrolls to roughly 460 metres The Hot 100 blends sales, airplay and streamsBillboard's main singles chart began in 1958 and now counts three kinds of data A vinyl side trades loudness for playing timeFitting more minutes on a disc means narrower grooves and a quieter cut Mastering for vinyl cuts a physical grooveA lathe engraves a lacquer disc that is plated and pressed

Tags: vinyl, singles, formats

RCA's seven-inch single spun at 45 rpm: the short answers

Where does this come from, and can I check it?: The 1949 format had a wide centre hole so automatic changers could grip it. The figure is taken from Library of Congress, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a music fact?: Yes. It sits on the Music shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.