subtractive synthesis

Subtractive synthesis is one of several methods of sound synthesis. In subtractive synthesis, frequencies are removed from a sound spectrum. In terms of the process, a voltage-controlled oscillator generates a sinusoidal signal or a frequency spectrum containing harmonics, i.e. a square, pulse or triangular signal. Downstream voltage-controlled filters filter out certain harmonics from the frequency spectrum, causing the same frequencies to sound different.

The oscillator frequency, the filter function and the downstream amplifiers are voltage-controlled, which means that subtractive synthesis can be used to create a wide variety of sounds synthetically.

Synthesizers with subtractive sound synthesis can be described by the terms Voltage Controlled Oscillator( VCO), Voltage Controlled Filter( VCF) and Voltage Controlled Amplifier( VCA). Synthesizers with subtractive synthesis often use lowpass filters with relatively high slopes, since steeper filter curves limit the harmonic spectrum better. In addition to lowpass filters, however, highpass filters and bandpass filters are also used.