The 12-inch single (often simply called 12") is a type of gramophone record that has wider groove spacing compared to other types of records. This allows for louder levels to be cut on the disc by the cutting engineer, which in turn gives a wider dynamic range, and thus better sound quality. This record type is commonly used in disco and dance music genres, where DJs use them to play in discos or clubs. They are generally intended to be played at 45 rpm.
The 12-inch single gramophone record came into existence with the advent of disco music in the 1970s. The first 12" (30 cm) single was actually a 10" (25 cm) acetate used by a mix engineer (Jose Rodriquez) in need of a Friday night test copy for famed disco mixer Tom Moulton. As no 7" (18 cm) acetates could be found, a 10" (25 cm) blank was used. Moulton, feeling silly with a large disc which only had a couple of inches of groove on it, asked Rodriguez to re-cut it so that the grooves looked more spread out. Because of the wider spacing of the grooves, a broader overall dynamic range (distinction between loud and soft) was made possible. This was immediately noticed to give a more favorable sound for discothèque play.
Moulton's position as the premiere mixer and "fix it man" for pop singles ensured that this fortunate accident would instantly become industry practice. This would perhaps have been a natural evolution: As songs became much longer than had been the average for a pop song, and the DJ in the club wanted sufficient dynamic range, the format would have surely had to be changed from the 7 inch (18 cm) single eventually.
Also worth noting is that the visual spacing of the grooves on the 12" assisted the DJ in locating the approximate area of the "breaks" on the disc's surface (without having to listen as he dropped and re-dropped the stylus to find the right point). A quick study of any DJ's favorite discs will reveal mild wear in the "break points" on the discs' surfaces that can clearly be seen by the naked eye, which further eases the "cueing" task (a club DJ's tone-arm cartridge will be heavily weighted and mild wear will seldom spoil the sound quality). Many DJ-only remix services, such as Ultimix and Hot Tracks, issued sets with deliberately visualised groove separations (i.e., the record was cut with narrow and wider spacings that could be seen on the surface, marking the mix points on the often multi-song discs).
A broader dynamic range or louder recording level requires more space as the grooves' excursions (i.e., the width of the groove waves and distance traveled from side to side by the turntable stylus) become much greater in amplitude, especially in the bass frequencies so important for dance music. Many record companies began producing 12-inch (30 cm) singles at 33⅓ rpm, as the slower speed enhances the bass on the record. By the same token, however, 45 rpm gives better treble response and was used on many 12-inch singles, especially in the UK.
The first very first 12" single was released in 1973 by soul/R&B musician/songwriter/producer Jerry Williams, Jr. aka Swamp Dogg. 12" promotional copies of "Straight From My Heart" were released on his own Swamp Dogg Presents label (Swamp Dogg Presents #501/SDP-SD01, 33⅓ r.p.m.) with distribution by Jamie/Guyden Distribution Corporation. It was manufactured by Jamie Record Co. of Philadelphia PA. The B-side of the record is blank.
The first official promotional 12" single was Southshore Commissions' "Free Man". At first, these special versions were only available as promotional copies to DJs. Examples of these promos, released at almost the same time in 1975 are, GARY TOMS EMPIRE - "Drive My Car", DON DOWNING - "Dream World", BARRABAS - "Mellow Blow", THE TRAMMPS - "Hooked For Life", ACE SPECTRUM - "Keep Holdin' On", SOUTH SHORE COMMISSION - "Train Called Freedom", THE CHEQUERS - "Undecided Love", ERNIE RUSH - "Breakaway", RALPH CARTER - "When You're Young and in Love", Michael ZAGER & The Moon Band Feat. Peabo BRYSON - "Do it With Feeling", MONDAY AFTER - "Merry-Go-Round", THE RITCHIE FAMILY - "I Want To Dance" and FRANKI VALLI - "Swearin' to God".
By 1976, with the release of "Ten Percent" by Double Exposure on Salsoul Records, the new format was sold to the general public. The second song found on a 12" single is "Love to Love You Baby" by Donna Summer, released in 1976. This song was originally a full side of her North American debut release, but released again in early 1977 backed with "Try Me, I Know We Can Make It", on the Oasis/Casablanca label.
Increasingly in the 1980s, many pop and even rock artists released 12-inch singles that included longer, extended, or remixed versions of the actual track being promoted by the single. These versions were frequently labeled with the parenthetical designation "12-inch version", "12-inch mix", "extended remix", "dance mix", or "club mix".
Later musical styles took advantage of this new format and recording levels on vinyl 30 cm (12 in) maxis have steadily increased, culminating in the extremely loud (or "hot") cuts of drum and bass records of the 1990s and early 2000s.
Many record labels produced mainly 12-inch singles (in addition to albums) during the 1980s, such as Factory Records, who only ever released a handful of 7-inch (18 cm) records. One of Factory's resident artists, alternative rock/dance quartet New Order, produced the biggest-selling 12-inch record ever in the United Kingdom, "Blue Monday", selling about 800,000 copies on the format and over a million copies in total. It was somewhat helped by the fact that Factory did not release a 7-inch version of the single until 1988, five years after the single was originally released as a 12-inch-only release. By way of comparison, "Blue Monday" came in 76th on the 2002 UK list of all-time best-selling singles.
The term "12-inch" usually refers to a single with several remixes. Now that advances in compact disc player technology have made the CD acceptable for mixing and "turntablism", the term maxi single is increasingly used.
In the mid-late 1980s, prior to the rise in popularity of the CD single, vinyl maxi-singles for popular artists often included "bonus" songs that were not included on albums, just as a 7" single included a B-side cut that was often not to be found on the referenced album. Many CD singles contain a number of such cuts, in a manner similar to the older EP vinyl format.
In the days of the 7" single, and especially in R&B releases, the single would occasionally be "flipped" by radio DJs who found the B-side cut to be better for airplay than the intended A-side. One noteworthy example is the now-classic "I'll Be Around", the first of the Spinners' Thom Bell-produced hits for Atlantic Records in the mid 1970s. Around the time 12" releases became standard for pop records, this practice faded, because of the increase in marketing costs, the reliance on video to sell single releases, and the public's expectation of quality packaging with photo or picture sleeves. The birth of the CD single has all but ended such practices, and it seems apparent that the growing trend of Internet marketing will put an end to such moves.
http://www.djsportal.com/disco-single-story-p-171.html?cPath=2 12 DISCO SINGLE - story in pix]