Going in a different direction for my case so I’m selling my Error Instruments KHarper synth module. Comes with original box and power cable. A bit of info for it:

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.