Gramophone record

A gramophone record, (also phonograph record - often simply record) is an analog sound recording medium: a flat disc rotating at a constant angular velocity, with inscribed spiral grooves in which a stylus or needle rides. Analogue audio recording onto a disc was the main technology used for the storing of recorded sound for most of the 20th century. By 1988 digital media such as the compact disc surpassed the gramophone record in popularity, but gramophone records continue to be made (although in very limited quantities) into the 21st century, particularly for DJs doing live remixes and for local acts recording on small regional labels. Used records are still sold in decent numbers and remain a common part of many music collections. Most major releases still recieve a vinyl release, sometimes with bonus tracks and artwork.

Basics

The normal commercial disc is normally engraved with two sound bearing concentric spiral grooves, one on each side of the disc, running from the outside edge towards the centre. (A small number of early phonograph systems and radio transcription discs started the groove from the inside rather than the edge of the disc. A small number of novelty records were manufactured with multiple separate grooves.) Other albums, like Goodbye Blue and White by Less Than Jake, a hidden track, or the entire side, will be played from the centre out). Since the late 1910s, both sides of the record have been used to carry the grooves.

Related Topics:
Radio - Goodbye Blue and White - Less Than Jake - 1910s

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Common formats

• 12" (30 cm) 33⅓ rpm long-playing (LP) format
• 12" (30 cm) 45 rpm extended-playing (12-inch (30 cm) single, Maxi Single and EP) format
• 7" (17.5 cm) 45 rpm (single) format

Less common formats

• 10" (25 cm) 33⅓ rpm long-playing (LP) format
• 10" (25 cm) 45 rpm extended-playing (EP) format
• 7" (17.5 cm) 33⅓ rpm extended-playing (EP) format
• 16⅔ rpm format for voice recording, and (very rarely) for music too http://www.plosin.com/milesAhead/prlp/prlp7150.html http://www.worldwidewax.com/hrecs/g0/g018.htm
• 12" (30 cm), 10" (25 cm) and 7" (17.5 cm) picture discs and shaped discs
• Specialty sizes (5" (12 cm), 6" (15 cm), 8" (20 cm), 9" (23 cm), 11" 28 cm), 13" (33 cm))
• Flexidiscs, often square 7"s (17.5 cm)

The majority of records are pressed on black vinyl. The colouring material used to blacken the transparent PVC plastic mix is Carbon Black, the trade name for the finely divided carbon particles produced by the incomplete burning of a mineral oil sourced hydrocarbon. Without this, the record would be transparent and would show the dirt collected in the grooves, the scratch marks and other damage to both sides of the record. Carbon Black also increases the strength of the disc.

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Some records are pressed on vinyl dyed other colours than black, or with pictures in them. These are relatively rare and tend to become collectors' items. In recent years, the release of records on high quality, colour vinyl - often with large inserts that can be used as posters - has been seen as an attempt to make records competitive with compact discs.

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Vinyl record standards for the United States follow the guidelineshttp://www.aardvarkmastering.com/riaa.htm of the RIAA (the Record Industry Association of America). The inch designations are nominal, and are not accurate indications of the diameter. The actual dimension of a 12 inch record is 302 mm (11.89 in), for a 10 inch it is 250 mm (9.84 in), and for a 7 inch it is 175 mm (6.89 in).

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Records made in other countries are standardized by different organizations, but are similar in size. The record diameters are typically 300 mm, 250 mm and 175 mm in most countries.

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There is usually an area around 10 mm (1/4") wide at the outer edge of the disk where the groove is widely spaced and silent. This section allows the stylus to be dropped at the start of the record groove, eliminating the risk of damage to the recorded section of the groove when the stylus head is dropped carelessly onto the LP. Towards the label centre, at the end of the groove there is another silent section known as the "Run-off" where the groove joins itself to form a complete circle. When the stylus reaches this point, it circles repeatedly until lifted from the record. Automatic turntables rely on the sudden change of direction of travel of the arm as it reaches these more widely spaced grooves to trigger the mechanism that raises it.

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To allow for auto-changing turntables, records typically have a raised outer edge and label area. This allows records to be stacked onto each other without the relatively delicate grooves coming into contact, reducing the risk of damaging them. Auto-changing turntables do not have the ability to play both sides of an LP without the user having to reload them, though juke boxes with their more sophisticated loading systems could do this.

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In between each track on the recorded section of a record there is usually a short gap where the groove is widely spaced. This space is clearly visible so it is easy to find an particular track.

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