Basic Subtractive Synth

A classic subtractive synthesizer with oscillators, filter, envelope, and modulation.

The basic subtractive synth patch

Overview

Subtractive synthesis starts with a harmonically rich waveform (saw or square) and uses a filter to "subtract" frequencies, shaping the tone. Combined with envelopes for dynamic control, this creates expressive, versatile sounds.

Character: Warm, punchy, expressive Good for: Bass, leads, pads, keys

Modules Used

• 1x Oscillator
• 1x SVF Filter
• 1x VCA
• 2x ADSR Envelope
• 1x Keyboard Input
• 1x Audio Output

Patch Diagram

┌──────────┐      ┌──────────┐      ┌─────┐      ┌────────┐
│ Keyboard │─V/Oct─▶│Oscillator│─Audio─▶│Filter│─Audio─▶│  VCA   │─▶ Output
│          │      │  (Saw)   │      │(SVF) │      │        │
└────┬─────┘      └──────────┘      └───▲──┘      └───▲────┘
     │                                  │             │
     │ Gate                             │             │
     │         ┌──────────┐             │      ┌──────┴──────┐
     └────────▶│  ADSR 1  │─────────────┘      │   ADSR 2    │
               │ (Filter) │                    │ (Amplitude) │
               └──────────┘                    └─────────────┘
                                                      ▲
                                                      │ Gate
               ┌──────────────────────────────────────┘
               │
        [From Keyboard Gate]

Step-by-Step Setup

1. Add Core Modules

Add and position:

1. Keyboard Input (left side)
2. Oscillator (center-left)
3. SVF Filter (center)
4. VCA (center-right)
5. Audio Output (right)

2. Create the Audio Path

Connect the main audio signal:

[Oscillator Audio Out] ──▶ [Filter Input]
[Filter Lowpass Out] ──▶ [VCA Input]
[VCA Output] ──▶ [Audio Output Mono]

3. Add Pitch Control

[Keyboard V/Oct] ──▶ [Oscillator V/Oct]

4. Add Amplitude Envelope

Add ADSR 1 for volume control:

[Keyboard Gate] ──▶ [ADSR 1 Gate]
[ADSR 1 Env] ──▶ [VCA CV]

ADSR 1 Settings (Amplitude):

5. Add Filter Envelope

Add ADSR 2 for filter movement:

[Keyboard Gate] ──▶ [ADSR 2 Gate]
[ADSR 2 Env] ──▶ [Filter Cutoff CV]

ADSR 2 Settings (Filter):

6. Set Module Parameters

Oscillator:

• Waveform: Saw (harmonically rich)
• Frequency: 440 Hz (controlled by keyboard)

Filter:

• Cutoff: 800 Hz (base cutoff)
• Resonance: 0.3 (slight emphasis)
• CV Amount: 0.6 (envelope range)

VCA:

• Level: 1.0
• Response: Exponential

Playing the Patch

1. Press keys on your computer keyboard
2. Adjust filter Cutoff for brightness
3. Adjust filter Resonance for character
4. Modify envelopes for different articulation

Variations

Punchy Bass

Oscillator: Square wave
Filter Cutoff: 400 Hz
Filter Resonance: 0.1
ADSR 1: A:1ms D:100ms S:0.5 R:50ms
ADSR 2: A:1ms D:200ms S:0.1 R:50ms

Smooth Lead

Oscillator: Saw wave
Filter Cutoff: 2000 Hz
Filter Resonance: 0.2
ADSR 1: A:50ms D:100ms S:0.8 R:500ms
ADSR 2: A:20ms D:500ms S:0.5 R:300ms
Keyboard Glide: 100ms

Plucky Keys

Oscillator: Saw wave
Filter Cutoff: 1500 Hz
Filter Resonance: 0.4
ADSR 1: A:1ms D:200ms S:0.0 R:100ms
ADSR 2: A:1ms D:150ms S:0.0 R:100ms

Soft Pad

Oscillator: Triangle wave
Filter Cutoff: 3000 Hz
Filter Resonance: 0.1
ADSR 1: A:500ms D:200ms S:0.8 R:1000ms
ADSR 2: A:200ms D:500ms S:0.6 R:800ms

Enhancements

Add a Second Oscillator

For thicker sound:

[Oscillator 2 (Saw, +7 cents detune)] ──▶ [Mixer]
[Oscillator 1] ──▶ [Mixer]
[Mixer] ──▶ [Filter]

Add Vibrato

For expressiveness:

[LFO (5 Hz, low depth)] ──▶ [Oscillator FM]

Add Effects

For space:

[VCA] ──▶ [Delay] ──▶ [Reverb] ──▶ [Output]

Troubleshooting

No sound: Check all connections, ensure keyboard is focused

Always sounds: Check envelope gate connections

Too quiet: Increase VCA level or Output level

Too bright: Lower filter cutoff or envelope CV amount

Too dull: Raise filter cutoff or use Saw waveform

What You've Learned

• Basic subtractive synthesis signal flow
• Using separate envelopes for amplitude and timbre
• How filter cutoff and resonance affect tone
• Creating variations with envelope settings