What's in a Number?
Records are often referred to by the number of revolutions that they make on a turntable per minute, or RPMs. This number gives the listener an idea of how much is recorded on the record [source: Phonograph].
- 78s -- Manufactured until the late 1950s, these records made 78 revolutions per minute and carried only about five minutes of sound. The fragile records were made with shellac.
- 33s or LPs -- Short for "long play," LPs rotated at 33 and one-third revolutions per minute. Successfully introduced in 1948, they played for about 25 minutes per side. Because they were made of polyvinyl chloride, these records earned the nickname "vinyl."
- 45s -- Only 7 inches (17.5 centimeters) in diameter, the 45 debuted in 1949 and was often called a "single," as it held one song on each side.
How a Vinyl Record is Made
The success of the gramophone to play recorded sounds was dependent on the ability to mass produce records.
The process of making records has its roots in Thomas Alva Edison's phonograph. First, a master recording is made, usually in a studio where engineers perfect the recorded sound. Then an object called a lacquer is placed on a record-cutting machine, and as it rotates, electric signals from the master recording travel to a cutting head, which holds a stylus, or needle. The needle etches a groove in the lacquer that spirals to the center of the circular disc. The imprinted lacquer is then sent to a production company.
There, the lacquer is coated in a metal, such as silver or nickel, to produce a metal master. When the metal master is separated from the lacquer, the resulting disc has ridges instead of grooves. The metal master is then used to create a metal record, also called the mother, which is then used to form the stamper. Stampers are just negative versions of the original recording that will be used to make the actual vinyl records.
Next, the stamper is placed in a hydraulic press, and vinyl is sandwiched in between. Steam from the press softens the plastic as the stampers push an impression of the master recording onto it. Finally, the disc is stiffened using cool water.
Once the record is ready to be played, it will need a proper machine to bring its sounds to life. Up next, we'll break down how exactly a record player's components work together to bring you the music.