Control voltage

CV/gate (an abbreviation of control voltage/gate) is an analog method of controlling synthesizers, drum machines and other similar equipment with external sequencers. The control voltage typically controls pitch and the gate signal controls note on-off.

This method was widely used in the epoch of analog modular synthesizers, beginning in the 1960s and up to the early 1980s. It was mostly superseded by the MIDI protocol, which is more feature-rich, easier to configure reliably, and more readily supports polyphony. The advent of digital synthesizers also made it possible to store and retrieve voice "patches" - eliminating patch cables and (for the most part) control voltages. However, numerous companies – including Doepfer, who designed a modular system for Kraftwerk in 1992Buchla, MOTM, Analogue Systems, and others continue to manufacture modular synthesizers that are increasingly popular and rely primarily on analog CV/gate signals for communication. Additionally, some recent non-modular synthesizers (such as the Alesis Andromeda) and many effects devices (including the Moogerfooger pedals by Moog as well as many guitar oriented devices) include CV/gate connectivity. Many modern studios use a hybrid of MIDI and CV/gate to allow synchronization of older and newer equipment.

In early modular synthesizers, each synthesizer component (e.g., low frequency oscillation (LFO), voltage controlled filter (VCF), etc.) can be connected to another component by means of a patch cable that transmits voltage. Changes in that voltage cause changes to one or more parameters of the component. This frequently involved a keyboard transmitting two types of data (CV and gate), or control modules such as LFOs and envelope generators transmitting CV data:

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