Subtractive synthesis is a method of sound synthesis commonly used in modular synthesizers. Subtractive synthesis involves shaping a harmonically rich waveform by removing or “subtracting” certain frequencies from it using filters. The basic components of a subtractive synthesis patch include an oscillator, a filter, and an amplifier, often with additional modulation sources like envelopes and low-frequency oscillators (LFOs).
In the context of modular synthesizers, subtractive synthesis typically involves the following steps:
- Generate a harmonically rich waveform using an oscillator module (VCO). Common waveforms include sawtooth, square, or triangle waves.
- Sculpt the frequency content of the waveform by sending it through a filter module (VCF), which can be a low-pass, high-pass, band-pass, or other types of filters. This process removes or attenuates certain frequencies, emphasizing or de-emphasizing specific harmonics.
- Control the amplitude of the filtered signal using an amplifier module (VCA) often modulated by an envelope generator to shape the overall volume contour of the sound.
- Further modulate the parameters of the oscillator, filter, and amplifier using additional modulation sources like LFOs, sequencers, or other control voltage sources to create movement and dynamic changes in the sound.
Subtractive synthesis is a widely used technique in modular synthesizers because of its versatility and simplicity, allowing users to create a vast range of sounds by shaping and modulating the harmonic content of waveforms.
