Guides

How subtractive synthesis works

Most analog and virtual synths use “subtractive synthesis”: generate a harmonically rich waveform, remove parts of it with a filter, then shape its loudness and tone over time with an envelope.

1. Oscillator — the raw material

The signal starts at the oscillator (OSC). A saw wave is the brightest (most harmonics), a square is hollow, while triangle and sine are smooth.

The more harmonics a wave has, the more the filter has to work with — which is why the saw is the default starting point for basses and leads.

2. Filter — carving

A low-pass filter reduces harmonics above the cutoff frequency, making the tone darker and rounder. Raising resonance emphasizes the area around the cutoff for that classic synth color.

Move the cutoff with an envelope or LFO and the sound comes alive — this is the heart of subtractive expression.

3. Envelope & amplifier

After the filter, the signal passes through the amp (VCA), where an ADSR envelope shapes its loudness over time.

With the same oscillator and filter, a different envelope turns the patch into a pluck, a pad, or a bass.

Understanding ADSR envelopes

ADSR stands for Attack, Decay, Sustain and Release — the curve that a parameter (usually loudness) follows over time as you press and release a key.

Attack & Decay

Attack is the time from key-press to peak level. Short means a punchy start; long means a pad that swells in gradually.

Decay is the time from the peak down to the sustain level, shaping the percussive character.

Sustain & Release

Sustain is a level, not a time — the proportion of loudness held while the key stays down.

Release is the tail after you let go. Longer values leave a longer trailing decay.

Filter envelopes

Envelopes can drive the filter cutoff too, not just loudness. A fast attack and quick decay on the cutoff give you the classic synth pluck/bass that snaps open and shut.

Filters and resonance

A filter sculpts tone by passing or reducing certain frequency bands. The most common one in synthesis is the low-pass (lets low frequencies through).

Cutoff frequency

A low-pass filter progressively reduces frequencies above the cutoff. Lower it and highs disappear for a dark, warm tone; raise it for brightness and clarity.

Resonance

Resonance boosts frequencies right around the cutoff. A little adds color; a lot produces a whistling peak that can even self-oscillate.

Filter types

A high-pass thins the sound by removing lows; a band-pass keeps only a middle band for a telephone-like tone. 12dB vs 24dB is how steep the carving slope is.

Make a supersaw lead

A supersaw stacks many detuned saws into one massive, wide lead — the backbone of trance and festival EDM.

1. Stack voices

Set OSC A to SAW, raise VC (Voices) to 7 and spread DET to ≈58. One note becomes choir-thick.

2. Shape it

Open the filter CUT to around 85 for brightness; keep attack short (0.02) and release a touch longer (0.35).

3. Add space

Add chorus and reverb for width. Play a chord and you have the classic trance lead.

Make a Reese bass

A Reese bass is two detuned saws interfering to create a moving, growling low end — a drum & bass signature.

1. Two saws

Set OSC A and B to SAW, drop B by −12 semitones and detune slightly. Their interference makes the growl.

2. Go dark

Drop to octave −1, lower CUT to ≈48 for weight, add a little RES for definition, and add SUB for the floor.

3. Movement

Route an LFO or macro to CUT and sweep it slowly for a living Reese.

Make an acid bass (303-style)

Acid is the squelch of high resonance + a filter envelope. It defines acid house and techno.

1. Saw + low cutoff

SAW, octave −1, and a low CUT (≈34).

2. Resonance & envelope

Raise RES high (≈68) and filter ENV DEPTH to ≈70. Each attack snaps the filter open then shut for the signature color.

3. Short decay

Use a short decay so the squelch closes fast. Add glide for a true 303 feel.

Make an FM bell (DX-style)

FM wobbles one sine’s frequency with another to make metallic harmonics — the DX7 bells and e-pianos.

1. Sine + FM

Set the waveform to SINE, enable FM mode and raise the FM amount to ≈56. Bell-like harmonics appear.

2. Strike then fade

Set attack near 0, low sustain, and use decay/release for the fade length.

3. A living attack

Modulate the FM amount with an envelope so the metallic edge is strong only on the attack. Add reverb for space.

Make an electric piano

An electric piano is FM’s cousin: dial the FM amount back and add chorus for a soft, Rhodes-like key.

1. Gentle FM

SINE + FM mode, FM amount ≈34 (lower than a bell). Too high gets cold.

2. Key feel

Short attack + medium decay/sustain gives a struck, played feel.

3. Warm with chorus

Enable chorus for a slight shimmer and a touch of reverb for the classic electric piano.