Control voltage (CV) refers to a continuous electrical signal that is used to modulate or control various parameters of modules within a modular system. It is the single most essential element to understand in modular synthesis.
Control voltage signals typically vary between a specific voltage range, such as -5V to +5V or 0V to +10V, depending on the synthesizer format and the module’s design. The voltage levels of a CV signal correspond to specific parameter values or ranges, with higher voltages generally representing higher values (e.g., higher pitch or greater modulation depth).
In modular synthesis, CV signals can originate from various sources, such as:
- Envelope generators: These produce CV signals that change over time according to the envelope’s attack, decay, sustain, and release (ADSR) stages, typically used to control the amplitude of a sound or to modulate other parameters, such as filter cutoff frequency.
- Low-frequency oscillators (LFOs): These generate slow, periodic CV signals that can be used to modulate parameters in a cyclical manner, such as creating vibrato, tremolo, or filter sweeps.
- Sequencers: These generate a series of CV signals based on a programmed sequence of values, often used for creating melodies or controlling rhythmic patterns.
- Random sources: These generate random or pseudo-random CV signals that can be used to introduce unpredictability and variation to a patch, such as random pitch, filter modulation, or panning.
- Manual controllers: These include devices like knobs, sliders, or touch-sensitive controls that allow users to generate CV signals by manipulating the controller manually.
CV signals are routed within a modular synthesizer using patch cables, connecting the output of a CV source module to the input of a destination module. This flexibility in routing and combining CV signals is a key characteristic of modular synthesis, allowing for extensive experimentation and the creation of complex and evolving soundscapes.