Emulation of Operational Amplifiers and Diodes in Audio Distortion Circuits

Title
Emulation of Operational Amplifiers and Diodes in Audio Distortion Circuits
Authors
Rafael C. D. Paiva , Stefano D'Angelo and Vesa Välimäki Department of Signal Processing and Acoustics Aalto University School of Electrical Engineering Espoo, Finland, and
Jyri Pakarinen Dolby Laboratories, Stockholm, Sweden.
Abstract
This work presents a generic model to emulate distortion circuits using operational amplifiers and diodes. Distortion circuits are widely used for enhancing the sound of guitars and other musical instruments. This paper introduces a new model for an ideal operational amplifier that does not include implicit equations and is thus suitable for implementation using wave digital filters (WDF). Furthermore, a novel WDF model for a diode is proposed using the Lambert W function. A comparison of output signals of the proposed models to those obtained from a reference simulation using SPICE shows that the distortion characteristics are accurately reproduced over a wide frequency range. Additionally, the proposed model enables real-time emulation of distortion circuits using ten multiplications, 22 additions, and two interpolations from a look-up table per output sample.
Status
Sound samples

 

http://www.acoustics.hut.fi/publications/papers/ieee-cs-2012-opamp/
Author: Rafael Paiva
Modified: 20.3.2012, Rafael Paiva

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