Z-Wah: Appropriating the Wah via Digital Impedance Synthesis

Francisco Bernardo; Andrew McPherson

Z-Wah: Appropriating the Wah via Digital Impedance Synthesis
Image credit: Francisco Bernardo; Andrew McPherson

Abstract:

Digital impedance synthesis is a viable technique for appropriating and augmenting electronic musical instruments and effects. It enables in-circuit augmentation by replacing selected analog components with a low-latency embedded system that presents a programmable voltage-current relationship to the surrounding circuit. By defining the hybrid boundary between the analog and digital as an impedance relationship rather than a unidirectional control stream, the technique supports reciprocal coupling of subsystems, mutual influence, dynamic emergent interaction and complex behaviour. We demonstrate the approach with an augmented wah pedal that embeds a hybrid virtual-analog system which replaces key passive elements inside the resonant network, potentially allowing a continuum from close emulation to deliberate mismatch and instability as musical material. The contribution is a method for augmenting legacy electronic instruments from within their circuitry and expanding the space of repeatable and exploratory modifications, along with design implications for directionality, feedback, and the aesthetics of hybrid idiosyncrasy.