Acetate disc

The damage to the edge of this test acetate shows that the underlying material is aluminum, rather than the vinyl of a record sold at retail.

An acetate disc (also known as a test acetate, dub plate, lacquer, or transcription disc) is a type of mechanical sound storage medium closely related to the gramophone record and its manufacturing process. Acetates are typically produced from a master tape recording. By electroplating the acetate master, stampers (special moulds) can be created, which in turn are used to press large quantities of records. Acetates are also used for testing the quality of the tape-to-disc transfer. A typical acetate disc is an aluminum disc, 10 or 12 inches in diameter, that is covered with a thin coating of nitrocellulose lacquer in which the sound groove is cut. Discs of this type can be played on any normal phonograph, but wear out very quickly. Some acetates are highly prized for their rarity.

Uses

Acetates have not always been used solely as a means of checking the quality of a disc recording. They were widely used before magnetic tape was invented and in the modern era they are used by dance music DJs. Because of their limited useful lifetime, acetates were often used as "demos" of new recordings by artists and record labels.

Recording

From the 1930s to the late 1950s, before the introduction of magnetic tape, recordings were often made directly to acetate discs (see direct to disc recording). Acetates were also used as a storage medium for radio commercials; since commercials only run for a limited time it doesn't matter if the disc wears out relatively quickly. During the early tape era (1950s, primarily), acetate discs and portable disc recorders competed with magnetic tape as a location-recording medium, both for broadcast and semi-pro use. Acetate discs inherently are less durable than magnetic tape, and also cannot be directly edited (cut and spliced).

Gramophone disc mastering

In preparation for a record pressing, acetates are used for quality control prior to the production of the stampers, from which retail copies of the record will be pressed. The purpose of the test acetate(s) in the mastering process is to allow the artist, producer, engineer, and other interested parties to check the quality of the tape-to-disc recording process and make any necessary changes to ensure that the audio fidelity of the master disc will be as close as possible to that of the original master tape. The actual stampers can be made either from normal acetates, or from a DMM disc (see Direct Metal Mastering).

Dance music

In the dance music world, DJs cut new or otherwise special tracks on acetates, in order to test crowd response and find potential hits. This practice started as early as in the 1960s in Jamaica, between so called sound systems, as a way of competing and drawing bigger crowds. These discs are known as dubplates. But the word "dubplate" can interchangeably mean an actual disc or just the music/recording, which can be on any other medium (e.g. CD). Dubplates were used by reggae soundsystems worldwide, and later adopted by producers of various dance music genres, most notably Drum and Bass and Dubstep. Trading dubplates between different DJ's is an important part of DJ culture. Actual acetate dubplates are declining in popularity, and being increasingly replaced by CD's because of weight, durability and cost.

Material and packaging

Despite their name, most acetate discs do not contain any acetate. Instead, most are an aluminum disc with a coating of nitrocellulose lacquer. (Glass was also used during World War II, when aluminum was in short supply.) This production process results in a disc that is different in many ways from the vinyl records sold to customers at retail. Whereas vinyl records are light and semi-flexible, acetates are rigid and somewhat heavier. More significantly, the thin coating of lacquer on an acetate is much more susceptible to wear; the playback head of a stylus quickly damages the grooves of the record such that after only a relatively few number of plays the audio quality is noticeably degraded. This is not a problem, however, since acetates are only test recordings and are not designed to be able to stand the test of time.

Acetates typically come in two sizes: 10" discs for singles and 12" discs for albums. The record's sleeve is typically nothing more than a generic cover from the manufacturing company and the disc's label is similarly plain, containing only basic information about the content (title, artist, playing time, etc.), which is usually typed but is often just hand-written. Many acetates also have a second hole near the center hole to ensure that the disc does not slip while it is "cut" or recorded.

Value

Due to their rarity, some acetates can command high prices at auction. Brian Epstein's collection of Beatles acetates fetched between $1,000 and $10,000 per disc. An acetate from The Velvet Underground, containing music that would later appear on their first album, The Velvet Underground & Nico, sold on eBay in 2006 for $25,200.

See also

• Fonopost A service offering recordings by mail using acetate discs.