Many voltages in a modular synth – including the output of an audio oscillator, and most low frequency oscillators – fluctuates between positive and negative voltages. This is known as a bipolar voltage. Some voltages – such as the output of an envelope generator – only vary between 0 volts and some maximum positive voltage; this is referred to as unipolar. This is handy for “opening” a voltage-controlled amplifier or filter.
This variation between modules and functions drives some users crazy, especially when you want to use a voltage to control something other than what the module’s creator might have envisioned. That’s why it’s useful to have a utility module or two that can scale (attenuate or optionally amplify) and offset a voltage: among other tasks, it can convert a bipolar voltage to unipolar and vice versa.« Back to Glossary Index