Acetate disc

An acetate disc (also known as a test acetate, lacquer, or transcription disc) is an audio disc that is created as part of the process of producing a gramophone record. Acetates are typically produced from the master tape recording and represent an intermediate stage prior to the production of the master disc - the disc from which retail copies of the recording will be pressed. The purpose of the acetate 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.

Material and packaging

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.

Despite their name, most acetate discs do not contain any acetate. Instead, they comprise 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 pressings 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 in order to indicate clearly that the disc is test acetate.

Use in the mastering process

When recorded from a master tape, an acetate represents an intermediate stage prior to the production of a master disc from which retail copies of the recording will be pressed. The purpose of the acetate 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.

Other uses

Test acetates have not always been used solely as a means of checking the quality of a disc recording.

From the 1930s to the early 1950s, before the introduction of magnetic tape, recordings were often made directly to acetate discs, which then served as the master from which other discs were made. 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. Also, in the dance music world, DJs sometimes create acetates containing various sounds, samples and loops that they can use during their performance. These discs are known as "dub plates".

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 and Nico, sold on eBay in 2006 for $25,200 , with an earlier dishonoured bid of $155,401.