The Minichord is a compact, chord-focused musical instrument developed by Benjamin Poilve through a co-creation effort with Seeed Studio. Designed for musicians of all skill levels, it combines a tactile chord selection system with a responsive touch interface and MIDI output capabilities. With fully open-source firmware and hardware design, the device encourages community-driven modification and customization.

The Minichord is powered by a 600 MHz ARM Cortex-M7 processor and includes a 1000 mAh Li-poly battery, providing up to 7 hours of runtime on a full charge. It features a 3.5mm audio output jack, a micro-USB port for charging and data, and visual indicators for preset and rhythm modes. Firmware updates are handled using PJRC’s Teensy Loader tool, and the hardware design is fully accessible for modification and extension.

Minichord Chord Mapping Table
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The front panel houses 21 dedicated chord buttons for direct access to major, minor, and seventh chords. A “sharp” button shifts notes by a semitone, and combinations of buttons enable more complex chords such as major 7ths, minor 7ths, augmented, diminished, and slash chords. This layout supports both beginner-friendly usage and more advanced harmonic exploration.

A key feature is the harp-style touch zone—a vertically aligned strip divided into 12 sections. Users can trigger melodic lines by tapping or strumming across the sections, with note output dynamically linked to the selected chord. This allows for expressive transitions between harmonic and melodic playing.

Three potentiometers provide real-time control over chord volume, harp volume, and a preset-specific parameter. Each knob also supports a secondary function when adjusted while holding the “sharp” button, offering additional sound-shaping options.

Minichord includes 12 built-in sound presets, all of which can be modified using a browser-based tool called Minicontrol. This editor allows users to adjust synthesis parameters for both chord and harp engines, manage the 12 onboard preset slots, and share patches using encoded preset strings. Parameters are grouped by global, harp, and chord categories.

Synthesis Schematic
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As a USB MIDI device, the Minichord presents two independent MIDI ports—one for the chord section and one for the harp. This allows for flexible routing in digital audio workstations and virtual instrument setups. It supports standard MIDI protocols and is compatible with macOS, Windows, and Linux. In simpler environments like GarageBand, both outputs are merged into a single MIDI stream.

Additional features include a rhythm mode with both continuous and discrete playback options, and a 16-step arpeggiator that can be enabled via a long press of the rhythm button. Tempo can be adjusted manually using tap tempo.

Minichord Synthesizer
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Comprehensive documentation is available, including usage guides, firmware instructions, and detailed synthesis schematics for both harp and chord sections.

Further information

The Minichord Synthesizer can be pre-ordered for $129.00 from Seeed Studio.