Magnetic Resonator Piano

The key's first string, its motion in slow motion and hugely exaggerated, from the engine's partials. The coil over it lights up with its current; the hammer strikes at the left, an eighth of the way along; the bridge is at the right. A partial whose node sits under the coil cannot be driven.

The last eight seconds of the focused note: the coil current's peak (gold), the string's swing under the coil (blue, in dB) and how far the phase-locked loop has pulled its oscillator from the partial it drives (green, in cents). A bass string swells for seconds; a treble string within a fraction of one.

A struck note thins from the top down. A driven note does the opposite: it grows from nothing, and holds its partials as long as the key is down. The partials sit a little sharp of the harmonics (the wire's stiffness), which is why a rich drive never quite locks its upper harmonics.

For each partial: how strongly the coil pulls it (the string's shape under the coil, averaged over its 21 mm), and what the drive sends (outlined). The partial the loop drives is filled. A bar near zero is a partial with its node under the coil.