(Fr. séquenceur; Ger. Sequencer; It. sequencer).
An electronic device that creates automated repeatable sequences of sound. The sequencer was pioneered in the analogue synthesizers designed by Donald Buchla in the mid-1960s, and continues to be incorporated into larger, especially modular synthesizers and also produced as a self-contained unit. Its automated functioning lends itself to digital and computerized control. In earlier models a series of knobs permitted the user to determine the value of up to three parameters (such as frequency, duration, filtering and modulation) for each step in the sequence, which typically comprised eight or more steps; such a repeated pattern is known as a loop, by analogy with a handmade loop of magnetic tape. The output of each step consists of a voltage whose level is determined by the position of the relevant knob(s), while the overall speed at which the sequencer cycles through the steps can be fixed or manually varied. Such a sequence of output voltages may vary a selected parameter of another device, such as a synthesizer module, by means of Voltage control.
Subsequently the capacity and capabilities of larger sequencers have been greatly expanded, running to many thousands of steps; since the mid-1980s they have often been replaced by equivalent software programmes for increasingly powerful microcomputers, controlling synthesizers and other devices via MIDI. Because with MIDI every parameter setting is codified numerically, a sequencer is capable of storing recordings of sequences of MIDI events (the information about the sounds, not the sounds themselves, in all parameters), and there is thus little differentiation now between a sequence as described above and a digital recording of a passage of music. The software provides a virtual multitrack recorder and mixing desk, and often also enables the music to be viewed and printed out as notation in both musical and graphic (‘player piano’) formats. At the other extreme the availability of sequencers has given rise to forms of rock music (Rap, etc.) that are based on the invasive monotonous rhythmic ostinatos of drum machines (see Electronic percussion) and simplistic looped electronic bass lines.
HUGH DAVIES