After the war the record changed shape twice and gained a second channel. The album as a long listening experience, and the single as a three-minute hit, both come from these years.
The LP
Columbia Records introduced the LP, the long-playing record, in 1948: a 12- or 10-inch disc of PVC, "vinyl", with a fine "microgroove", played at 33⅓ rpm. Each side of a 12-inch LP held about 25 minutes, around 50 in all. The whole US industry soon adopted it. Records for the home until then were mostly noisy shellac with a wide groove at about 78 rpm.
The 45 single
RCA Victor's rival format was the smaller 7-inch "45", the single. The two competed, and the LP eventually came out on top. Vinyl records were introduced in 1948 and by 1958 had become standard, replacing the 78.
Stereo
Modern stereo was invented in the 1930s by the British engineer Alan Blumlein at EMI, who patented stereo records, stereo film and also surround sound. In two-channel stereo recording, two microphones are placed at chosen positions and record at the same time; a coincident pair keeps the phase difference between channels small. Stereo was added to the LP in 1957.
| Year | Format | What it held |
|---|---|---|
| 1948 | LP, 33⅓ rpm, 12-inch vinyl | About 25 minutes a side |
| Same years | 45, 7-inch single | RCA Victor's rival format |
| 1957 | Stereo on the LP | Two channels in one groove |
| By 1958 | Vinyl standard | The 78 retired |
What it changed
With 25 minutes a side, an artist could plan a set of songs as one work. With two channels, the mix gained a left and a right: panning became a decision, and the stereo image something an engineer designed.
Sources
Every date, name, tempo and origin on this page comes from these pages, read on 2026-10-24.