A type of synthesizer developed in the 1950s and popularized in the 1970s in which components such as controllers, oscillators, filters, and amplifiers are designed as separate devices and interconnected by patch cords. Every module has various control and audio input and output sockets that are used for interconnecting with the others. Early modular synthesizers didn’t have MIDI capabilities, memories, or presets, and they very rarely had hard-wired internal connections; thus, all connections were from module to module via cables.

The underlying principle of analog modular synthesis is voltage control, used to control VCOs or trigger an ADSR envelope. Well known modular synths were created by Moog, Buchla, Serge, and others. A number of modular synth manufacturers continue to develop and build systems today.