Voltage Standard

Pitch is everything in a synth. To keep oscillators in tune, Eurorack follows the 1 V/oct standard — every extra volt pushes the pitch up by exactly one octave. This idea goes back to Robert Moog, who wanted tuning to feel musical instead of purely technical. 

Musicians typically think in terms of intervals — it’s irrelevant to them that 440 Hz is one octave lower than 880 Hz. 

In 1 V/oct, the frequency follows f ∝ 2^V. That means every time you add 1 volt, the oscillator frequency doubles (one octave up). Subtract 1 volt, and the frequency halves (one octave down). This makes it easy to transpose pitches without having to readjust everything.

1 V/Oct = Standard for Pitch Control

+5 V ≈ Gate/Trigger (not fully standard)

10 Vpp ≈ Standard for Audio Signals

Another reason for using 1 volt as a reference is that it offers sufficient accuracy to control oscillators via potentiometers and keyboards, while keeping the voltage low enough that a range of 4–5 octaves does not require something like 20 volts.

For gate and trigger signals, an informal standard has emerged at around 5 V. However, this is not fully standardised and may vary between manufacturers, so always check your manuals to confirm the signal types your modules require or produce.

Audio signals also follow certain standards. The waveforms typically fluctuate between -5 V and +5 V, giving a 10 V peak-to-peak range. This provides enough headroom when voltages are mixed and add up.