Minichord: Open-Source Pocket Omnichord with DIY Spirit and Modern Synthesis
Open-Source Pocket Omnichord with Modern Synthesis
The Minichord brings the classic Omnichord experience into the modern age with an open-source design that fits in your pocket. Created by Benjamin Poilve, this tiny synthesizer combines the intuitive chord-playing approach of vintage autoharp instruments with contemporary digital synthesis and MIDI capabilities.
What Makes the Minichord Special?
The Minichord captures the essence of the beloved Suzuki Omnichord while adding modern features that go beyond what the original could do. It's built around a Teensy 4.0 microcontroller and features both hardware and software that are completely open-source, allowing musicians and makers to customize every aspect of the instrument.
Key Features and Design
Chord Generation System
- 21 main chord buttons arranged in 7 columns representing the C Major scale
- Each column contains major, minor, and 7th chord variations
- Sharp modifier button for chromatic chord access
- Advanced chord selection by combining multiple buttons
- Key and scale settings for different musical contexts
Touch-Sensitive Harp Zone
- 12-section vertical touch strip for individual note triggering
- Strum across all sections or pick notes individually
- Hold notes by maintaining contact with sections
- Arpeggiator mode for melodic patterns
Modern Synthesis Engine
The Minichord features surprisingly deep synthesis capabilities:
- Multiple oscillator types with configurable waveforms
- Built-in effects including tremolo, vibrato, and delay
- Envelope and filter controls for sound shaping
- 12 internal presets with full customization options
- Stereo panning and reverb controls
Power and Connectivity
- 7-hour battery life for true portability
- USB charging via mini cable
- MIDI over USB when connected to computer
- Works as both instrument and MIDI controller
Open-Source Philosophy
One of the Minichord's most appealing aspects is its completely open approach:
Hardware Design
- Full Bill of Materials available
- PCB schematics and Gerber files for main and touch boards
- 3D printable case files for custom enclosures
- Licensed under Creative Commons Attribution-NonCommercial 4.0
Software Freedom
- Complete firmware source code available on GitHub
- Minicontrol web interface for creating custom presets
- Software licensed under 3-clause BSD License
- Based on PJRC's Audio library for Teensy
Programming and Customization
The Minichord's synthesis engine offers extensive customization through its Minicontrol web interface:
- Configure oscillator parameters and waveforms
- Adjust envelope and filter settings separately for harp and chord sections
- Create custom rhythm patterns with BPM control
- Set up complex modulation and effects chains
- Export and share preset configurations
Strengths and Considerations
What It Does Well
- True portability: Battery operation enables music creation anywhere
- Deep customization: Open-source design allows complete personalization
- Educational value: Great for learning synthesis and DIY electronics
- MIDI capabilities: Functions as both instrument and controller
- Community-driven: Active development with user contributions
What to Consider
The Minichord embraces its DIY prototype aesthetic - while charming, it may not appeal to those seeking polished commercial products. You'll need to install the Minicontrol editor yourself, though preset configurations are available online. The open-source nature means ongoing development, but also potential compatibility changes over time.
Building Your Own
The Minichord can be built from scratch using the comprehensive documentation at minichord.com and the GitHub repository. The project includes everything needed: PCB designs, component lists, 3D printing files, and detailed assembly instructions.
For those preferring a ready-made option, Seeed Studio offers pre-assembled units, helping bring this community project to a wider audience.
Final Thoughts
The Minichord successfully modernizes the Omnichord concept while maintaining the intuitive, approachable nature that made the original so beloved. Its open-source philosophy sets it apart from commercial instruments, offering unprecedented customization and learning opportunities.
While it may look like a prototype, the Minichord's synthesis capabilities and programming depth rival much more expensive instruments. For musicians interested in chord-based composition, DIY electronics, or simply having a unique portable instrument, the Minichord offers an compelling combination of nostalgia and innovation.
The active community and ongoing development ensure the Minichord will continue evolving, making it as much a platform for musical exploration as it is a finished instrument.