Harper  Electronic Harp with 4 strings

kHarper is not a conventional synthesizer.
It’s a tactile sound design instrument for musicians and sound artists interested in texture, distortion, and sonic experimentation.

kHarper is an experimental string instrument built around a physical implementation of the Karplus-Strong string synthesis model. It combines digital sound engines with a tactile interface, allowing you to pluck, touch, and shape strings directly. The result ranges from cinematic swells to distorted textures and delicate plucked tones.

Designed as a platform for exploration, kHarper works as a standalone device or in Eurorack format and supports future sound engines and firmware updates.

Core Design

• 4 touch-controlled strings — each string acts as an independent voice

• LED bar per string shows activity and string behavior

• Touch strips allow direct interaction with the string models

• Tone knob per string with CV input for modulation

• Gate input per string to trigger plucks externally

• Built from multiple Karplus-Strong sound engines producing rich, dynamic string behavior

Touching and plucking the models introduces subtle variations and natural chaos, making each interaction slightly different—much like a physical instrument.

Sound Engines

kHarper includes 9 sound models, organized into three character groups:

Herring – cinematic textures

• Deep, atmospheric sounds

• Slow emotional chords and large cinematic swells

KoiKarp – rhythmic and percussive

• Short, punchy plucks

• Ideal for rhythmic patterns and sequences

Dolphin – experimental and glitchy

• Overdriven and distorted algorithms

• Noisy, chaotic, and unpredictable textures

Each group contains three variations, giving nine selectable engines in total.

Controls

• Pond / River / Ocean — selects one of three engine variations

• Herring / KoiKarp / Dolphin — selects the sound engine family

• Tone and Decay controls with knob and CV modulation

• STRUM gate input — triggers all four strings simultaneously

• Per-string tone knob + CV input

• Per-string gate input for individual plucks

Connectivity

Inputs

• MIDI In

• CV and Gate inputs

• STRUM gate input

Outputs

• Stereo audio output (Left / Right)

• Control outputs: Gate and CV

Open Platform

kHarper is designed as an evolving sound platform.

A USB port allows new firmware, algorithms, and sound engines to be uploaded. Possible future expansions include:

• Alternative sound engines

• Generative or ambient patches

• New quantization systems

• Expanded modulation and sequencing

• Custom community firmware