The Sparksichord: Practical Implementation of a Lorentz Force Electromagnetic Actuation and Feedback System

Adam Schmidt; Jeffrey Snyder; Gian Torrano Jacobs; Joyce Chen; Joseph Gascho; Andrew McPherson

The Sparksichord: Practical Implementation of a Lorentz Force Electromagnetic Actuation and Feedback System
Image credit: Adam Schmidt; Jeffrey Snyder; Gian Torrano Jacobs; Joyce Chen; Joseph Gascho; Andrew McPherson

Abstract:

In line with a sustained community interest in electromagnetic actuation of musical instruments, we describe practical considerations for Lorentz Force actuation in conductive strings, exemplified by the Sparksichord – an augmented harpsichord that uses Lorentz Force actuation, optical feedback, and analog circuitry to sustain vibrations of its brass strings. Electromagnetically-actuated and feedback instruments have grown increasingly popular in NIME, though most systems rely on the use of solenoid-style electromagnetic coils. By running current through the string itself, Lorentz Force actuation offers an alternate arrangement of magnets and wire that can afford new modes of interaction, a broader frequency response, and cheaper implementation. We aim to empower practitioners with a toolbox for designing and building actuated instruments of this style and describe our specific implementation for this instrument.