The most common standard for controlling pitch in a modular synthesizer. Under the system, increasing the voltage going into a VCO (Voltage Controlled Oscillator) 1 volt – say, from 0.5v to 1.5v – would raise its pitch by one octave.

Following this 1v/octave scheme requires an exponential (steeply curved) relationship between voltage and frequency, as each change in octave requires an additional doubling or halving in frequency (for example, raising the control to the oscillator 2 volts would result in a frequency that was four times higher; a 3 volt increase results in a frequency eight times higher, etc.). Precisely reproducing this exponential curve from module to module is one of the weak links in analog synthesizers in particular, as temperature changes and aging electronic components can result in a deviation in pitch. These deviations are often referred to as tracking errors.

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