Subtractive synthesis is the most common method of creating sounds on a synthesizer, and it works by starting with a harmonically rich waveform and then “subtracting” frequencies with a filter until you get the tone you want. If you are new to sound design, subtractive synthesis is the best place to start because its signal flow is intuitive: you can hear exactly what each control does.
This guide explains the building blocks and then walks you through making a simple sound, so the controls on any synth start to make sense.
How subtractive synthesis works
The name says it all: you begin with more harmonic content than you need, then remove what you do not want. The classic signal chain is:
- Oscillator generates a raw, harmonically rich waveform.
- Filter removes frequencies to shape brightness.
- Amplifier controls the volume over time.
Envelopes and LFOs then add movement to those stages. For the bigger picture of how synths are built, see our explainer on what a synthesizer is.
Step one: the oscillator
Oscillators produce the basic waveform. Each has a different harmonic character:
- Sawtooth — bright and buzzy, full of harmonics. Great for leads and basses.
- Square/pulse — hollow and reedy, good for woodwind-like and retro tones.
- Triangle — softer, with fewer harmonics.
- Sine — pure, no harmonics, ideal for sub bass.
Subtractive synths usually start with the brighter waveforms because there is more for the filter to work with.
Step two: the filter
The filter is the heart of subtractive synthesis. The most common type is a low-pass filter, which lets low frequencies through and cuts the highs above its cutoff point. Lowering the cutoff darkens the sound; raising it brightens it. The resonance control emphasises frequencies right at the cutoff, adding bite or a vocal quality. Sweeping the filter cutoff is one of the most recognisable sounds in electronic music.
Step three: envelopes
Envelopes control how a parameter changes over the life of a note. The standard is the ADSR envelope — attack, decay, sustain, release. Applied to the amplifier, it shapes volume; applied to the filter, it shapes how brightness evolves. Our full ADSR envelope guide breaks down each stage in detail.
Step four: LFOs and modulation
An LFO (low-frequency oscillator) adds automatic, repeating movement — a wobble on the pitch (vibrato), a pulse on the volume (tremolo), or a sweep on the filter. LFOs are what stop synth sounds from feeling static. For a deeper look, read what is an LFO.
Building a simple patch
Try this on any subtractive synth to hear the parts working together:
- Select a sawtooth oscillator.
- Lower the low-pass filter cutoff until the sound is dark, then add a little resonance.
- Set a filter envelope with a quick attack and medium decay so the sound opens up then closes — an instant “pluck.”
- Add a slow LFO to the filter cutoff for gentle movement.
From there, experiment. Changing one control at a time is the fastest way to learn what each does.
Using your synth sounds in a track
You play subtractive synth patches with a controller — see what a MIDI controller is — then sequence and balance them like any other part. The wider mixing and mastering hub covers fitting bright, filtered synth sounds into a full mix without harshness.
Frequently asked questions
Why is it called subtractive synthesis?
Because you start with a harmonically rich waveform and then subtract frequencies with a filter to shape the final tone, rather than building the sound up from simpler parts.
What is the most important control in subtractive synthesis?
The filter, especially the low-pass cutoff and resonance. It defines the brightness and character of the sound, and sweeping it is central to the subtractive sound.
Is subtractive synthesis good for beginners?
Yes. Its signal flow — oscillator, filter, amplifier — is intuitive, and each control has an audible effect, so it is the easiest method to learn sound design with.
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