Control Voltage (Often abbreviated to CV) is at it’s most basic a signal which can be applied to an analog circuit to modify it’s behavior. This modification can take many forms but typically with analog synthesis we will be using it to either turn a circuit on and off, or adjust the frequency and intensity of oscillation (which will adjust tone and volume). What makes this interesting is it allows us to modify or control various components of a synthesizer from a separate circuit or device. Probably the easiest example of this would be a basic CV keyboard, When you press a key on the keyboard a DC signal is sent from the keyboard to your synthesizer which tells the synthesizer what note to play and how long to play it. When you press different keys on the keyboard the signal sent will be a slightly different voltage which will modify the synthesizers oscillation, amplifier and envelope to different degrees thus producing different notes and sounds.
To continue reading please visit Control Voltage 101 in The Basics