On June 21, 1948, the first 33 rpm in history was launched on the market, thanks to Columbia Records. An epochal innovation was therefore presented in New York, compared to the much older 78 rpm, on the market since the late 1800s.

The 78 rpm was completely replaced, thanks to this new lighter, modern, resistant format but above all thanks to its extended recording capacity: the new 33 rpm, in fact, allowed a reproduction of about 23 minutes of music per side.

Long playing (also known as LP) or 33 rpm is the standard format of vinyl records on which record albums are recorded in analog form; by extension it also indicates the collection of musical pieces, even when published on completely different media from the vinyl record both in terms of technology and sampling and playback methods such as cassette, compact disc or Digital Audio Tape.

Long playing was introduced in 1948 by Columbia Records and progressively supplanted the 78 rpm shellac record, thanks to the better quality and durability of vinyl.

The vinyls reached their greatest success around the end of the 1970s, when almost a billion records were sold.

Starting in the late eighties, the advent of the compact disc reduced interest in vinyl records, which were gradually supplanted, becoming a niche product for collectors and enthusiasts, sometimes printed in limited edition. In the 21st century, the interest in vinyl records started to rise again while that for CDs went into crisis.

Long playing generally consists of two sides indicated on the central labels as sides A and B, or 1 and 2, each of which can contain about 30 minutes, reaching a maximum of about 40 minutes per side, especially for operas. . The longer the disc life implies a lower sound level and lower dynamics.

LPs are played through the turntable: the musical piece is played through a diamond or sapphire needle inserted in the head which, during rotation at a predefined speed, mechanically transmits the irregularities of the groove engraved on the surface of the record to a complex electromagnetic, which transforms movement into an electrical signal.

The process of recording LPs and any other vinyl support is based on the creation of a master disc in two phases.

In the first phase, the sound to be recorded, collected with microphones or other analog instruments, is translated into a groove that a metal pin traces on a disc of deformable plastic material. This disk, called a lacquer, is placed on a lathe that turns at the same speed as the support to be produced, in this case 33 rpm and ⅓ per minute.

Once the shape has been taken, a cast of the lacquer is made (which is imprinted on one side only and whose name recalls that of shellac), generally by pouring the metal itself in fusion carried out in order to fill the grooves left by the stylus. This cast (called metal master) serves in the second phase as a casting mold for the mass production of vinyl records.

Due to their physical characteristics, both the lacquer and the metal master undergo rapid deterioration with use and therefore sometimes more master discs are produced, or “second generation” lacquers are made, obtained by mold and not by engraving. in order not to stop production. In some cases the process is carried out directly, before the start of industrial printing.

An important starting point for a growing music market, also advantageous for artists, who began to produce their own music at decidedly reduced prices, giving people the opportunity to enjoy music in a simpler way.