This tutorial will cover the basic principles of the Wave Digital Filter (WDF) approach to virtual analog modeling, incorporating recent work. Recent research has expanded the class of circuits that can be modeled with this approach far beyond the original simple linear, passive, static, ladder circuits considered in the 1970s and 80s, to include analog circuits with multiple nonlinearities, time-varying components, complex topologies, and active devices. Recent research has also relaxed assumptions about signal variables (traditionally only voltage waves), discretization methods (traditionally only bilinear transform), and simulation time steps (traditionally fixed), now admitting a wide class of signal variables, traditional and novel discretization methods, and variable time steps.
Dr. Kurt James Werner has been a Lecturer in Audio at the Sonic Arts Research Centre (SARC) of Queen's University Belfast since early 2017. His research sits at the intersection of Wave Digital Filters, computer modeling of circuit-bent instruments, and the history of music technology. As part of his Ph.D. in Computer-Based Music Theory and Acoustics from Stanford University's Center for Computer Research in Music and Acoustics (CCRMA), he wrote a doctoral dissertation “Virtual Analog Modeling of Audio Circuitry Using Wave Digital Filters.” This greatly expanded the class of circuits that can be modeled using the Wave Digital Filter approach, using the classic Roland TR-808 bass drum circuit as a case study. As a researcher, he also also worked on the history of analog drum machine circuits. As a composer, his music references elements of chiptunes, musique concrète, circuit bending, algorithmic/generative composition, and breakbeat.