The history of the turntable being used as a musical instrument has its roots dating back to the 1930s, 1940s and 1950s when musique concrète and other experimental composers (such as John Cage and Pierre Schaeffer), used them in a manner similar to that of today's producers and DJs, by essentially sampling and creating music that was entirely produced by the turntable. Cage's "Imaginary Landscape No. 1" (1939) is composed for 2 variable speed turntables, frequency recordings, muted piano & cymbal. Even earlier, Edgard Varèse experimented with turntables in 1930, though he never formally produced any works using them.
Examples of turntable effects can also be found on popular records produced in the 1960s and 1970's. Creedence Clearwater Revival's 1968 self-titled debut album features a backspin effect in the song "Walk on the Water". However, turntablism as we know it now did not surface until the introduction of hip hop in the late 1970s
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http://en.wikipedia.org/wiki/Technics_MK2
The Technics SL-1200 is a series of turntables manufactured since October 1972 by Matsushita under the brand name of Technics. Originally released as a high fidelity consumer record player, it quickly became adopted among radio and club disc jockeys. Since its release in 1978, SL-1200MK2
The SL-1200MK2, released in 1978, has a silver finish. This was a continuing trend, as later 1200 models would be silver and matte black. Technics improved the motor and shock resistance, added a ground wire, and
changed the rotary pitch control to a slider style.
http://en.wikipedia.org/wiki/Lenco
Lenco' is now a Dutch brand of audio & video equipment and part of the STL Group of brands.[1]
However, when audio hobbyists refer to Lenco turntables, they are typically referring to the defunct Lenco AG of Oberburg, Switzerland, a turntable manufacturer of the 1950-1980's
Pitch control
A variable speed pitch control (or vari-speed) is a control on an audio device such as a turntable, tape recorder, or CD player that allows the operator to deviate from a standard speed (such as 33⅓, 45 or even 78 rpm on a turntable). The latter term "vari-speed" is more commonly used for tape decks, particularly in the UK. Analog pitch controls vary the voltage being used by the playback device; digital controls use digital signal processing to change the playback speed or pitch. A typical DJ deck allows the pitch to be increased or reduced by up to 8%, which is achieved by increasing or reducing the speed at which the platter rotates. Turntable or CD playing speed may be changed for beatmatching and other DJ techniques, while pitch shift using a pitch control has myriad uses in sound recording.
Tapedeck speeds
There are many different tape speeds which are in use in all sorts of tape recorders. Most often these speeds appear on tapedecks. Variations in tape speed cause flutter, which can be reduced by using dual capstans. Higher speeds used in professional recorders are prone to cause "head bumps," which are fluctuations in low-frequency response. Multitrack technology enabled the development of modern art music and one such artist, Brian Eno, described the tape recorder as "an automatic musical collage device".