Random voltage refers to a control voltage (CV) signal that varies unpredictably over time, generated by a module designed to create random or stochastic fluctuations. This random voltage can be used to modulate various parameters of other modules in a modular synthesizer, such as oscillator frequency, filter cutoff, or amplitude, introducing organic, unpredictable, and evolving behaviors to the sound.
Random voltage is often generated using modules such as noise generators, sample & hold (S&H) circuits, or dedicated random voltage generators. Here are some examples of how random voltage is created and used in modular synthesis:
- Sample & Hold (S&H): A sample and hold module takes an input signal (often white noise) and samples it at regular intervals, determined by an external clock signal. The sampled voltage is then held constant until the next sampling event. This results in a staircase-like random voltage signal, which can be used to modulate other modules.
- Noise generator: A noise generator module can output different types of noise, including white noise, which contains random fluctuations in amplitude. By passing the noise through a low-pass filter, you can create slower and smoother random voltage signals.
- Dedicated random voltage generators: Some modules are specifically designed to produce random voltage signals with various degrees of control over the range, distribution, and smoothness of the output voltage. These modules often include options for generating random gates, triggers, or sequences as well.