A synth which is constructed from discrete functional modules (such as VCOs, VCAs, envelope generators, mixers, etc.), which the performer can purchase and install individually as needed to construct any desired configuration. The first practical synthesizers as we know them today, beginning with the work of Donald Buchla, Bob Moog and Herb Deutsch in the early 1960s, were modular in design construction. In a typical modular synth, all inputs and output within each module are accessible via jacks on the front panel, and are routed by the use of patch cords; there is no pre-defined routing. (If no patch cords are plugged in, the modular makes no sound.)