1VOct

1VOct, commonly written 1V/oct, is a control voltage standard used in voltage-controlled analog synthesizers to translate keyboard pitch into voltages for voltage-controlled oscillators (VCOs). In this scheme, voltage increases produce octave shifts, so a rise of one volt raises the pitch by one octave.

The relationship between voltage and frequency is exponential. If a VCO is calibrated to 1V per octave, the frequency f follows f = f0 × 2^(V/1V), where V is the control voltage. This means that a semitone step corresponds to roughly 0.0833 V, and the octave above involves a doubling of frequency. Practical systems commonly use 0–5 V or 0–8 V CV ranges, with 0 V typically aligning to a chosen reference pitch. Calibration and tuning of VCOs are important for accurate pitch tracking across octaves.

History and usage have made 1V/oct the de facto standard in many modular and semi-modular formats, including Eurorack. It originated in the late 1960s and was popularized by early analog synthesizers designed to be keyboard-driven. Over time, 1V/oct became widely adopted due to its straightforward musical mapping and compatibility with many keyboards, sequencers, and MIDI-to-CV converters.

Variants and compatibility notes: not all equipment adheres strictly to 1V/oct, and some gear uses different pitch standards such as Hz/V or 2V/oct. Modern systems may offer calibration options or cross-conversion to bridge these standards. When integrating modules and keyboards, it is common to verify pitch tracking across the keyboard range and adjust calibrations to maintain musical tuning.

See also: CV/gate, MIDI-to-CV, VCO, modular synthesis, Hz/V.