History & The Arts
Recording music and sound
...research at Columbia Records in America, demonstrated a 12-inch (30 cm) non-breakable microgroove vinyl disc capable of playing 23 minutes each side. Columbia called it the LP (for long-playing) disc. It revolved at 33⅓ rpm with up to 300 tracks to the inch (120 per cm). The rival company RCA-Victor seemed not to be impressed with the LP. They responded with a 7-inch...