PartialString

Method

1Model

PartialString simulates the vibration of a plucked string by numerically solving the one-dimensional wave equation in real time using the finite-difference time-domain (FDTD) method. The string is represented as a list of displacements in memory. A lower note requires a longer string, which needs more points to represent it. You can then excite the string at any point along its length, and the FDTD scheme will compute how that change in displacement propagates. A pickup measures the displacement at a chosen location, and this generates the audio output. 8-voice polyphony is supported (up to 8 simultaneous strings).

2Controls

You can set the position and shape of the excitation, both velocity-sensitive. An LFO can sweep the pickup position, up to audio rate for AM-like sidebands. The string's decay time is adjustable, with or without dampers applied. The dampers can behave like a piano's, closing when a note ends. Combined with a long undamped decay, this makes pad-like sounds. Reducing the simulation accuracy generates unrealistic, soft and inharmonic sounds.

3Performance

Simultaneously simulating many low notes (long strings) accurately is quite computationally intensive. PartialString will automatically reduce the accuracy of low notes if necessary to prevent CPU overload, and this is indicated on the UI. But on a modern CPU this shouldn't happen much, if at all.

Available for macOS, Windows and Linux. Free to download and use.