Sound Synthesizer

Any grouping of electronic equipment intended for sound synthesis. Such equipment usually incorporates a combination of oscillators, filters, mixers, envelope generators, white noise generators, switches, reverberation units, etc. The term is now generally applied to digital sound synthesizers as well as their analog antecedents.

Such equipment became popular in the early 1960s, the major types of which were those created by Donald Buchla (the Buchla Box), Robert A. Moog (the Moog synthesizer), Peter Zinovieff (the Putney and Synthi synthesizers), and ARP Corporation (the ARP synthesizer). Since then many types of smaller and larger synthesizers have entered the commercial market as their use has become popular in electronic music studios, classrooms, and among professional musicians.

Compare: Musique Concrete, Sound Object, Tape Music.

All analog synthesizers use the principle of voltage control to determine the values of the various sound parameters, and much of the use of a synthesizer involves the production, transformation and application of control voltages to units such as oscillators (to control frequency), amplifiers (to control amplitude), filters (to control cut-off frequencies and/or centre frequency and bandwidth), and mixers (to control amplitude of an input signal being mixed).

See: Direct Current, Rectification, Subaudio.

Sequences of control voltages may be produced by a keyboard or by a sequencer where the voltages are pre-set and then generated in a fixed sequence. The abbreviations VCO, VCA and VCF are used to describe voltage-controlled oscillators, amplifiers and filters, respectively.

Digital synthesizers utilize techniques of digital sound synthesis, ranging from those which implement specific synthesis algorithms, to those (called samplers) based on reproducing digitally sampled sounds, to those which are programmable and therefore can implement a variety of digital signal processing (DSP) techniques. Increasingly, however, stand-alone hardware digital synthesizers (other than keyboards and the like) are being replaced by systems implemented in software on general-purpose computers. See: Digital Recording.