Now we do mention 78RPM records because they are often mentioned when discussing vinyl record speeds as an option however they are very uncommon. They are often vintage records that are made of shellac instead of modern PVC records.
Nearly all of the records you can buy is one of three common speeds: 33, 48 and 78 rotations per minute, otherwise listed as RPMs. That term is exactly what it sounds like, referencing the speed at which the vinyl record you’re listening to is supposed to rotate on the turntable you’re using. If you play at the incorrect speed the music may sound a bit funny.
These numbers actually date all the way back to the original phonograph, which didn’t have an automated motor and instead worked off a hand crank. Legend has it that the average user cranked the device at around 80 RPM. As turntables with motors were developed and a standard speed was needed, 78 RPMs essentially rose up to answer that call. This format allowed for about three to four minutes per side.
33 RPM records rose to prominence when record companies realized that they could print information onto a smaller-sized record without losing any audio quality in the process. Suddenly, this format was capable of about a 22 minute playing time per side.
The major advantage that 45 RPM records brought to the table was again one of size. They were physically smaller than 78s, which meant that the records themselves could be produced less expensively. In terms of audio quality, the two were about the same, so that size quickly became a large part of the reason why 45s quickly surpassed 78s in terms of mass audience appeal.