Modeling Vintage Electronic Instruments and Enabling Digital Lutherie with Wave Digital Filters

Vintage electronic musical instruments are a key part of our sonic heritage and have remained enduringly fascinating to musicians. Unfortunately, they can be fragile, expensive, rare, and difficult to fit into a modern workflow. Certain custom-made electronic instruments were only accessible to a select few. Today, as the antique electronic components and knowledge needed to repair old instruments grow increasingly scarce, even formerly mass-produced instruments may not be widely available.
Thinking beyond availability, some musical practices intrinsically depend on modifying, “circuit bending,” or otherwise customizing the circuitry of electronic instruments. Increasing scarcity of vintage electronic instruments has a chilling effect on these practices. When an instrument is valuable enough, experimental hacks and modifications represent a serious risk.
One way to address these trends is mathematical modeling of audio circuitry. The Wave Digital Filter (WDF) method of digital filter design creates modular and typically stable digital algorithms based on analog “prototypes.” Recent advances have expanded the WDF approach so that it is valid for circuits with complicated topologies and multiple nonlinear electrical elements. This makes WDFs highly suitable for “Virtual Analog” modeling of audio circuits, whose sound and behaviour are often strongly dependent on feedback topologies and nonlinear devices (diodes, transistors, tubes, etc.).
In this talk, I’ll review the basics of Wave Digital Filter modelling, comment on the suitability of this approach for Virtual Analog, and demonstrate how WDFs can be used to model vintage musical instruments. Beyond mimicking vintage analog circuits, I’ll show how WDFs can be used as a tool of digital lutherie. Unfettered by the practical limits of hardware, circuit design principles can flourish in the digital domain, hopefully informing the design of novel audio effects and instrument that fuse analog charm with digital flexibility.