In the mid-1950s all record companies agreed to a common recording standard called RIAA equalization. Prior to the establishment of the standard each company used its own preferred standard, requiring discriminating listeners to use preamplifier with multiple selectable equalization curves.
A number of recordings were pressed at 16? RPM, but these were mostly used for radio transcription discs or narrated publications for the blind and visually impaired, and were never widely commercially available, although it was still common to see turntables with a 16 RPM speed setting produced as late as the 1970s.
The older 78 music record format continued to be mass produced alongside the newer formats into the 1950s, and in a few countries, such as India, into the 1960s. As late as the 1970s, some children's records were released at the 78 rpm speed.
The commercial rivalry between RCA Victor and Columbia Records led to RCA Victor's introduction of what it had intended to be a competing vinyl format, the 7" (175 mm) /45 rpm disc. For a two-year period from 1948 to 1950, record companies and consumers faced uncertainty over which of these formats would ultimately prevail in what was known as the "War of the Speeds".
Eventually the 12" (300 mm) 33? rpm LP prevailed as the predominant format for musical albums, and the 7" (175 mm) 45 rpm disc or "single" established a significant niche for shorter duration discs, typically containing one song on each side. The 45 rpm discs typically emulated the playing time of the former 78 rpm discs, while the LP discs provided up to one half hour of time per side (though typically 15 to 20 minutes). The 45 rpm discs also came in a variety known as Extended play (EP) which achieved up to 10-15 minutes play at the expense of attenuating (and possibly compressing) the sound to reduce the width required by the groove.
From the mid-1950s through the 1960s, in the U.S. the common home "record player" or "stereo" would typically have had these features: a three- or four-speed player with changer (78, 45, 33?, and sometimes 16? rpm); a combination cartridge with both 78 and microgroove styluses; and some kind of adapter for playing the 45s with their larger center hole. The large center hole on 45s allows for easier handling by jukebox mechanisms. RCA 45s can also be adapted to the smaller spindle of an LP player with a plastic snap-in insert known as a "spider"; such inserts were prevalent starting in the 1960s.