The Mellotron is an electro-mechanical, polyphonic tape replay keyboard originally developed and built in Birmingham, England, in 1963. It evolved from a similar instrument, the Chamberlin, but could be mass-produced more effectively. The instrument is played by pressing its keys, each of which presses a length of magnetic tape against a capstan, drawing it across a playback head. Then as the key is released, the tape is retracted by a spring to its initial position. Different portions of the tape can be played to access different sounds. Later models such as the M400, the best selling model, dispensed with the accompaniments and some sound selection controls in order to be used by touring musicians. The instrument’s popularity declined in the 1980s after the introduction of polyphonic synthesizers and samplers. Production of the Mellotron ceased in 1986, but it regained popularity in the 1990s and was used by several notable bands. This led to the resurrection of the original manufacturer, Streetly Electronics. In 2007, Streetly produced the M4000, which combined the layout of the M400 with the bank selection of earlier models. (Wikipedia Source)