Virtual Analog Modeling using Wave Digital Filters: a Tutorial Introduction
Abstract
In this tutorial, the basics of the "Wave Digital Filter" (WDF) approach to virtual analog modeling will be presented. The WDF concept was introduced as a generic digital filter design technique by Alfred Fettweis in the 1970s, and has been picked up slowly by the audio DSP community starting in the early 2000s. Today, WDFs are capable of modeling audio circuits with complex topologies (bridges, feedback, &c.) and multiple nonlinearities (diodes, transistors, &c.) and can be considered one of the main approaches to modeling audio circuits in software. A wide variety of audio circuits have been successfully modeled, including the Roland TR-808 bass drum, amplifier tone stacks, Ibanez Tube Screamer, OTA-based state variable filters, tone boosters, the Electro-Harmonix Big Muff Pi, the Korg MS-50 VCF, & Fender and Mesa Boogie preamplifiers. The main focus of the talk will be the basic mathematical concepts that underpin WDF modeling and tutorial examples, including a simple RC lowpass filter & the Hammond organ vibrato/chorus circuit. Some progress on modeling a mysterious analog filter from the Experimental Music Studios (EMS) of the University of Illinois at Urbana-Champaign (UIUC) will also be presented.
Bio
Kurt James WernerAbstract
In this tutorial, the basics of the "Wave Digital Filter" (WDF) approach to virtual analog modeling will be presented. The WDF concept was introduced as a generic digital filter design technique by Alfred Fettweis in the 1970s, and has been picked up slowly by the audio DSP community starting in the early 2000s. Today, WDFs are capable of modeling audio circuits with complex topologies (bridges, feedback, &c.) and multiple nonlinearities (diodes, transistors, &c.) and can be considered one of the main approaches to modeling audio circuits in software. A wide variety of audio circuits have been successfully modeled, including the Roland TR-808 bass drum, amplifier tone stacks, Ibanez Tube Screamer, OTA-based state variable filters, tone boosters, the Electro-Harmonix Big Muff Pi, the Korg MS-50 VCF, & Fender and Mesa Boogie preamplifiers. The main focus of the talk will be the basic mathematical concepts that underpin WDF modeling and tutorial examples, including a simple RC lowpass filter & the Hammond organ vibrato/chorus circuit. Some progress on modeling a mysterious analog filter from the Experimental Music Studios (EMS) of the University of Illinois at Urbana-Champaign (UIUC) will also be presented.