Virtual analog polyphonic synthesizer inspired by the legendary Moog synthesizers, Prophet synthesizer family by Sequential, and Oberheim.
Created by Jarmo Annala.
LeadSynth is a software synthesizer built with JUCE/C++ that recreates the warm, rich character of classic analog polysynths. It runs as a standalone macOS app or as a VST3/AU plugin in any compatible DAW.
- Dual oscillators with selectable waveforms (Sine, Saw, Square, Triangle) using polyBLEP anti-aliasing
- Oscillator 2 detune with coarse (+-24 semitones) and fine (+-100 cents) control
- White noise generator with level control
- Multi-mode ladder filter — switchable between 12 dB/oct (Oberheim-style) and 24 dB/oct (Moog-style) with cutoff, resonance, envelope amount, and key tracking
- Dual ADSR envelopes — independent filter and amplitude envelopes with real-time visualization
- LFO with rate, depth, and selectable destination (pitch, filter, or both)
- Glide/portamento with adjustable time
- 8-voice polyphony
- Patterns: Up, Down, Up/Down, Random
- Rate divisions: 1/4, 1/8, 1/8T (triplet), 1/16, 1/16T, 1/32
- Tempo: Internal BPM (30-300) or host sync
- Latch mode: Notes sustain after release; new notes replace when all keys released
- Octave range: 1-4 octaves
- Gate length: 5%-100%
- All arp settings saved per preset
| # | Name | Group | Inspired by |
|---|---|---|---|
| 001 | Analog Lead | Classic | Pink Floyd / MMEB |
| 002 | VH Jump Brass | Van Halen | "Jump" — Oberheim OB-Xa |
| 003 | VH Ill Wait Pad | Van Halen | "I'll Wait" — Oberheim OB-Xa |
| 004 | VH Why Cant Lead | Van Halen | "Why Can't This Be Love" — OB-Xa |
| 005 | VH Why Cant Arp | Van Halen | "Why Can't This Be Love" arp — OB-Xa |
| 006 | OB Brass | Classic | Oberheim brass |
| 007 | Moog Lead | Classic | Moog prog lead |
| 008 | OB Strings | Classic | Oberheim string pad |
| 009 | Prophet Lead | Classic | Sequential Prophet-5 |
| 010 | Analog Bass | Classic | Moog bass |
| 011 | KR Arp Seq | Knight Rider | Roland Jupiter-8 arpeggio |
| 012 | KR Brass | Knight Rider | Oberheim OB-X brass |
| 013 | KR Chords | Knight Rider | Sequential Prophet-5 chords |
| 014 | KR Deep Bass | Knight Rider | Moog Minimoog bass |
| 015 | KR Lead | Knight Rider | Roland Jupiter-8 lead |
| 016 | KR Odyssey | Knight Rider | ARP Odyssey |
- Custom analog-style UI with wood side panels, brushed metal faceplate, and metallic pointer knobs
- Real-time ADSR envelope visualization (amber curves)
- Real-time oscilloscope with 70s CRT phosphor aesthetic
- On-screen piano keyboard with computer keyboard input (two octaves)
- Preset browser with groupings and inspirations (click preset name)
- Resizable window with locked aspect ratio
- Kiosk/fullscreen mode
- Footer bar showing MIDI device, active octave range, voice count, and CPU load
- Click MIDI LEARN to enter learn mode (knobs turn green)
- Click any knob, then move a CC on your controller to assign it
- Assigned knobs show a blue tint and CC number label
- Mappings are saved per MIDI controller device and persist across sessions
- CLR removes all CC mappings
Two octaves mapped to the QWERTY keyboard:
Lower octave (black): S D G H J
Lower octave (white): Z X C V B N M
C D E F G A B
Upper octave (black): 2 3 5 6 7
Upper octave (white): Q W E R T Y U I
C D E F G A B C
Click the piano keyboard to give it focus, then play.
| Key | Action |
|---|---|
| Left / Right | Previous / next preset |
| Up / Down | Octave up/down (when keyboard focused) or preset switch |
| F | Toggle fullscreen (kiosk mode) |
| S | Panic — stop all sounding notes |
| Escape | Return focus from keyboard to main editor |
- macOS with Xcode Command Line Tools
- CMake (install via
brew install cmake) - JUCE Framework — cloned into the project root as
JUCE/
# Clone JUCE (if not already present)
git clone --depth 1 https://github.com/juce-framework/JUCE.git
# Build everything
./scripts/build-all.sh
# Run standalone
open build/LeadSynth_artefacts/Release/Standalone/LeadSynth.app| Script | Description |
|---|---|
scripts/build-all.sh |
Build all targets (Standalone, VST3, AU) |
scripts/build-standalone.sh |
Build standalone app only. Pass --run to launch after build |
scripts/install-plugins.sh |
Build and install VST3 + AU to system plugin folders |
scripts/clean.sh |
Remove build directory |
| Target | Path |
|---|---|
| Standalone | build/LeadSynth_artefacts/Release/Standalone/LeadSynth.app |
| VST3 | build/LeadSynth_artefacts/Release/VST3/LeadSynth.vst3 |
| AU | build/LeadSynth_artefacts/Release/AU/LeadSynth.component |
./scripts/install-plugins.shCopies to ~/Library/Audio/Plug-Ins/VST3/ and ~/Library/Audio/Plug-Ins/Components/. Restart your DAW after installing.
lead_vst/
├── Source/
│ ├── PluginProcessor.h/cpp # Audio engine, parameter system, state
│ ├── PluginEditor.h/cpp # UI, layout, visualizations
│ ├── SynthVoice.h/cpp # Per-voice DSP (oscillators, filter, envelopes)
│ ├── Oscillator.h # Band-limited oscillator (polyBLEP)
│ ├── LadderFilter.h # Multi-mode ladder filter (12/24 dB)
│ ├── Arpeggiator.h # Lock-free arpeggiator engine
│ ├── SynthLookAndFeel.h # Custom knob and UI rendering
│ ├── MidiLearnManager.h # Lock-free CC-to-parameter mapping
│ ├── SettingsManager.h # Per-device settings persistence
│ ├── PresetManager.h # Factory preset definitions
│ └── StandaloneApp.cpp # Custom standalone app with macOS menu
├── Assets/
│ ├── icon_1024.png # App icon source
│ └── LeadSynth.icns # Multi-resolution macOS icon
├── scripts/ # Build and install scripts
├── JUCE/ # JUCE framework
└── CMakeLists.txt # Build configuration
All rights reserved. This is a private project.