Subtractive Synthesis Tutorial: Bass, Lead, Pad and Pluck From a Saw

What is subtractive synthesis?

Subtractive synthesis builds sounds by taking away: you start with a waveform full of harmonics and remove the parts you do not want with a filter. Apple's Logic Pro guide borrows the Michelangelo line about carving David by cutting away everything that does not look like David, and describes the synth as filtering away parts of the frequency spectrum.^[1]

Sound On Sound's Synth Secrets defines it the same way: you attenuate or remove harmonics from harmonically rich waveforms, either statically or with filters, envelopes and modulators that change the sound over time.^[2] Most of the synths you already own, from Serum and Vital to Ableton's Drift, work on this principle even when they add wavetables or FM on top.^[3] If you want the bigger map of synthesis types first, read synthesis types explained.

Oscillator, filter, amp: the subtractive signal flow

The signal runs in one direction: the oscillator creates the raw tone, the filter removes frequencies, and the amplifier shapes loudness over time. Apple describes the filter as representing the frequency-dependent losses and resonances of an instrument's body, with the amplifier section shaping the filtered signal over time.^[1] Modulators such as envelopes and LFOs sit beside that chain and move its knobs.

The saw is the default starting point because it contains every harmonic, which gives the filter the most to work with. Apple lists the sawtooth as ideal for string, pad, bass and brass sounds.^[4]

Set up a clean init saw patch in Vital

Vital works well for this tutorial because its free Basic tier includes the full synth with all features.^[5] Any synth with one oscillator, one low-pass filter and two envelopes can follow along; the Vital beginner tutorial covers the interface if you have not opened it before.

1. Initialize
   Choose Initialize Preset from the preset menu. According to a community-written Vital user guide, this clears all settings and sets Osc 1 to a saw wave with a simple envelope and LFO.^[6]
2. Show cutoff in Hz
   In the Advanced tab, set Frequency Units to Hertz so the cutoff values in this tutorial match what you see.^[7]
3. Route through the filter
   Turn on Filter 1 and make sure Osc 1 is routed to it. Pick an analog low-pass; Vital's analog filters offer 12 and 24 dB slopes and a Blend control that morphs from low-pass to band-pass to high-pass.^[8]
4. Check the amp envelope
   Envelope 1 controls the patch's overall volume; Vital forum users describe it as hardwired to the master volume.^[9] Every patch below starts by setting it.
5. Save the init
   Save this state as a user preset called Init Saw so each patch below starts from the same place.

Patch 1: build a saw bass

A subtractive saw bass is a mono saw with a dark 24 dB low-pass filter and a short filter envelope that adds bite to each note. Play it between C1 and C3 while you set it up.

1. Voices to 1
   Set voices to 1 and turn on legato if you want slides; add 40-80 ms of glide for a smoother line.
2. Close the filter
   Analog low-pass at 24 dB, cutoff 250-400 Hz, resonance 10-20%, key tracking 0% so every note keeps the same tone.
3. Amp envelope
   Envelope 1: attack 0 ms, decay 300 ms, sustain 80%, release 40-80 ms.
4. Filter envelope
   Drag Envelope 2 onto the cutoff: attack 0 ms, decay 150-250 ms, sustain 0%, with a moderate amount so each note opens briefly.
5. Add a sub
   Turn on Osc 2 as a sine one octave lower at about -6 dB so the low end stays solid when the filter moves.
6. Grit last
   Raise filter drive a few dB for harmonics that help the bass read on small speakers.

For growls and heavier modulation, designing bass in Serum takes the same idea further.

Patch 2: build a saw lead

A saw lead keeps more of the harmonics, adds a little unison for size and uses vibrato and glide so it sounds played. Load Init Saw and play it between C4 and C6.

1. Thicken the saw
   Osc 1 unison 5 voices, detune about 20%, stereo spread moderate.
2. Open the filter
   Low-pass 12 dB, cutoff 2-4 kHz, resonance around 15%, key tracking 50% so high notes stay bright.
3. Amp envelope
   Attack 5 ms, decay 400 ms, sustain 70%, release 200 ms.
4. Filter accent
   Envelope 2 to cutoff with a small amount, attack 0 ms and decay 300 ms, so notes start slightly brighter.
5. Add vibrato
   LFO 1 to Osc 1 pitch, sine, about 5-6 Hz, very small amount, with a short delay so it arrives after the note starts.
6. Mono and glide
   Voices 1, legato on, glide 60-120 ms for slides between overlapping notes.

Patch 3: build a saw pad

A saw pad is a polyphonic, heavily filtered and slowly enveloped saw with wide unison and slow movement. Load Init Saw and hold three- or four-note chords while you set it up.

1. Widen the source
   Unison 6-8 voices, detune 25-30%, stereo spread high, random phase high so the stack sounds even.
2. Soften the filter
   Low-pass 12 dB, cutoff 800 Hz-1.5 kHz, resonance about 10%.
3. Slow the amp
   Attack 0.8-1.5 s, decay 1.5 s, sustain 80%, release 2-3 s.
4. Add slow motion
   LFO 1 to cutoff, synced to 2 or 4 bars, small amount, retrigger off so it keeps evolving across chords.
5. Clear the low end
   Add an EQ or high-pass around 150-200 Hz so the pad stays out of the bass and kick.

Long releases overlap, so keep an eye on CPU and voice count on dense progressions. Envelope timing is explained in ADSR envelopes explained.

Patch 4: build a saw pluck

A pluck is a saw that is bright for a split second and then closes down, which comes almost entirely from zero sustain on both envelopes. Load Init Saw and program a short melody of 8th or 16th notes.

1. Light unison
   Unison 3 voices with small detune, or leave it at 1 for a tighter sound.
2. Dark resting filter
   Low-pass 24 dB, cutoff 300-500 Hz, resonance 15-25%.
3. Zero-sustain amp
   Attack 0 ms, decay 250-400 ms, sustain 0%, release 200-300 ms.
4. Snappy filter envelope
   Envelope 2 to cutoff with a high amount: attack 0 ms, decay 150-250 ms, sustain 0%.
5. Velocity to brightness
   Map velocity to the Envelope 2 amount so harder notes open further.
6. Space
   Add a synced delay and a short reverb; plucks need the tail to feel full.

For trap-specific variations, see trap bells and plucks. For more on filter choices, see synth filter types explained.

The four patches at a glance, for any synth

Put the four recipes side by side and the lesson is obvious: the oscillator barely changes, while the filter, envelopes and voice mode do almost all the work. Use this table to rebuild the patches in Serum, Drift, Retro Synth or any other subtractive synth.

• Patch sounds thin Filter opened too far or no low-octave layer. Lower cutoff or add a sub oscillator.
• Patch sounds dull Cutoff too low with no envelope movement. Add a filter envelope instead of just opening the knob.
• Everything sounds the same You are only changing the oscillator. Change the envelopes first; they define the instrument.
• Clicks Attack or release at exactly zero on sustained patches. Raise them to a few milliseconds.