Creating your own unique sound palette is a challenging task that requires technical knowledge to correctly manipulate sound and connect synth modules. Since subtractive synthesis stands as a fundamental method, where tones and frequencies must be removed for the sound to take shape, on this blog, we’ll delve into the fundamentals of this type of synthesis based on my experience creating a synthesiser in Reaktor.
Key components in a subtractive synthesiser :
Oscillator: this module generates a repeating waveform (Sine, Sawtooth, Square or Triangle) which acts as our main source of audio to be manipulated. Using different types of waveforms can introduce totally different results.
Filter: Passing sound through a Voltage Controlled Filter (VCF), this module helps eliminate unwanted frequencies to manipulate and start giving shape to the sound.
Envelope Generator: It’s an amplifier that controls volume to further manipulate the sound by adjusting Attack, Decay, Sustain and Release stages (ADSR).
Low-Frequency Oscillator (LFO): This module operates in very low (inaudible) frequencies to modulate pitch, volume or filter cutoff.
Voltage Controlled Filter
An important step to start ‘sculpturing’ the desired timbre is the VCF. Low Pass Filters (LPF) and High Pass Filters (HPF) minimise specific frequency ranges by altering the sonic output through Cutoff and Resonance parameters to dictate the filter’s behaviour. This allows for further tonal adjustments by creating resonance (peak) based effects.
Envelope Generator
The VCA (voltage-controlled amplifier) controls the sound volume to create an ADSR envelope generator. As it affects the dynamics and speed of how the sound evolves, it opens the possibility of controlling the sound to construct short transient sounds (to recreate drum sounds) or long transient sounds (to recreate a violin crescendo).
LFO
Although it’s inaudible, the function of LFO is crucial to add movement and pitch variation to the sound. By adjusting the frequency range potentiometer, it can be automated to change the note so it can fluctuate to create a siren sound through the vibrato effect (when is connected to the pitch input of the main oscillator). On the other hand, the LFO can create a tremolo effect when it is connected to the amplitude input of the main oscillator.
To conclude, subtractive synthesis involves shaping sound by filtering and modulating different types of waveforms. It serves as a tool for creatives with the ability to deconstruct sound to be used for artistic (music) or crafting purposes (sound design). This guide elaborates on utilising oscillators, filters, and envelope generators to craft personalised sonic textures.