PartialString

PartialString is a free physically modelled string synthesiser that uses the finite-difference time-domain method to simulate plucked string vibrations. It is designed for use in digital audio workstations as an AU and VST3 plugin on macOS, Windows, and Linux. Different Instruments developed the tool to provide a physics-based approach to string synthesis.

The synthesiser numerically solves the one-dimensional wave equation in real time. A string is represented as a list of displacements in memory, with lower notes requiring longer strings and more points. Users can excite the string at any point along its length, after which the finite-difference time-domain scheme computes how the change in displacement propagates. A pickup measures displacement at a chosen location to generate the audio output. Up to 10-voice polyphony is supported, though the actual number of simultaneous strings is dynamically adjusted according to the computer's capability and the lengths of the strings being simulated.

Controls include the position and shape of the excitation, both of which are velocity-sensitive. An LFO can modulate the pickup position at rates up to audio rate, producing AM-like sidebands. The string's decay time is adjustable. The interface allows direct interaction by clicking on a visual representation of the string to change the plucking position.

PartialString is distributed at no cost. It is available for download from the Different Instruments website.