The Control Voltage, German control voltage, the modular synthesizers used in analog synthesizers, and above all to control the various parameters of a sound. Also known by the abbreviation CV / Gate technology is used for example to control on / off, pitch, volume and grade or quality of the filtering.
Was systematically introduced and successfully disseminated this principle to the sale of the synthesizer by Robert Moog. But numerous other devices such as Arp synthesizer, Korg MS10/20, EMS and Crumar mastered this technology. With patchbays you could interconnect all free for some devices.
In the 1980s, this analog control method has been largely displaced by the introduction of the MIDI protocol. With the advent of digitization, the corresponding musical instruments are also initially disappeared, but were in the techno era in the 1990s, a brief revival. Here in particular by the Roland TB- 303. Also various stage lighting via CV / Gate could be controlled, such as strobe lights.
A great advantage of the analog control is the high resolution. While MIDI with 7 bits just offers a resolution in 128 levels, an analog resolution is almost infinite. Another big difference is that will be differentiated in the control voltage is not between control and audio signals. Thus, audio signals can be used as control voltage, and vice -versa. Under MIDI they are divided into separate worlds.
Modern software synthesizers like Reason is possible these days to simulate a virtual analog control modules, for example, to effect not only the on and off of a note but also to determine the velocity.
In 2009 published Mark of the Unicorn ( MOTU ) with Volta a virtual instrument plug- in that allows precise control voltage controlled instruments on music software.