Also known as a half step or half tone, this is the smallest pitch division in most Western music – such as the difference between a C and a C#. With equal temperament (the most common way of tuning a Western scale), this pitch division is 1/12 of an octave.
In a typical modular synth that follows the 1 volt per octave (v/oct) standard for pitch control, changing the pitch voltage to an oscillator’s main input by 1/12 of a volt (0.08333 volts) results in a one semitone change in pitch. Given that funny-looking number, it’s now easy to understand why Buchla standardized on 1.2v/oct – so each semitone would be 0.1 volts.
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