Structurally Passive Scattering Element for Modelling Guitar Pluck Action

Gianpaolo Evangelista; Julius O. Smith III
DAFx-2010 - Graz
In this paper we propose new models for the plucking interaction of the player with the string for use with digital waveguide simulation of guitar. Unlike the previously presented models, the new models are based on structurally passive scattering junctions, which have the main advantage of being properly scaled for use in fixed-point waveguide implementations and of guaranteeing stability independently of the plucking excitation. In a first model we start from the Cuzzucoli-Lombardo equations [1], within the Evangelista-Eckerholm [2] propagation formulation, in order to derive the passive scattering junction by means of bilinear transformation. In a second model we start from equations properly modeling the finger compliance by means of a spring. In a third model we formalize the interaction in terms of driving impedances. The model is also extended using nonlinear (feathering) compliance models.