Loudspeaker virtualization–Part I: Digital modeling and implementation of the nonlinear transducer equivalent circuit

Abstract

This manuscript, the first of a two-part series, presents a methodology for efficiently implementing an equivalent circuit of nonlinear loudspeakers in the discrete-time domain. This is a crucial step that will allow us to design new algorithms for loudspeaker virtualization in part II of this series. The presented implementation, in fact, is based on Wave Digital Filter (WDF) principles, which lead to a fully explicit model, in the sense that no iterative solvers are needed to compute the output signal. The proposed WDF is highly efficient and modular, since the reference circuit is modeled as a computable interconnection of input-output processing blocks. The accuracy of the implementation is confirmed by comparing it to a ground-truth SPICE simulation of the reference circuit and to measurements on real loudspeakers. This confirms that the proposed Wave Digital modeling approach can be reliably used for the rapid simulation of the transduction behavior of a loudspeaker (within the frequency limits of validity of the equivalent circuit), and can be employed to develop the digital preprocessing method for loudspeaker virtualization described in the second manuscript of this two-part series.