Hz/Volt is a voltage standard used in modular synthesis to represent pitch information in control voltage (CV) signals. In the Hz/Volt standard, a 1-volt change in CV corresponds to a one-octave change in pitch. Specifically, a CV of 0 volts corresponds to a pitch of 0 Hz (no sound), while a CV of 1 volt corresponds to a pitch one octave higher at 440 Hz.
This voltage standard differs from other standards used in modular synthesis, such as the Volt/Octave standard, which uses a 1-volt change in CV to correspond to a change of one octave in pitch. In the Hz/Volt standard, the pitch range is represented linearly, meaning that equal changes in CV result in equal changes in frequency.
The Hz/Volt standard is used by some manufacturers of modular synthesizer equipment, while others use the Volt/Octave standard or other voltage standards. Some modular synthesizers are designed to support multiple voltage standards, allowing users to choose the standard that works best for their particular setup.