In modular synthesis, “DC” refers to Direct Current, a type of electrical current that flows in a constant direction. In the context of modular synthesizers, DC signals are essential for controlling parameter via modulation. Unlike audio signals, which are alternating current (AC) and vary in amplitude and frequency to produce sound, DC signals are used primarily for control voltages (CV).
Control voltages are DC signals that dictate various parameters of a synthesizer module, such as pitch, filter cutoff, amplitude, and other modulations. These voltages do not produce sound directly but control the behavior of modules that generate or modify sound. DC signals can be constant, providing steady control, or they can change over time, shaped by modules like envelopes, LFOs, or sequencers, to create dynamic changes in the sound.
Additionally, issues related to DC include DC offset, which occurs when a signal’s average voltage is shifted away from zero volts. This can lead to problems in audio fidelity, such as unwanted clicks, reduced headroom, or signal distortion, and is typically corrected with a high-pass filter or DC offset correction circuit in the signal path.
