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Open AccessFeature PaperArticle

Virtual Analog Models of the Lockhart and Serge Wavefolders

1
Aalto Acoustics Lab, Aalto University, 02150 Espoo, Finland
2
Native Instruments GmbH, D-10997 Berlin, Germany
3
Acoustics and Audio Group, University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK
*
Author to whom correspondence should be addressed.
This paper is an extended version of our paper published in the 14th Sound and Music Computing Conference (SMC-17), Espoo, Finland, 5–8 July 2017.
Academic Editor: Stefania Serafin
Appl. Sci. 2017, 7(12), 1328; https://doi.org/10.3390/app7121328
Received: 12 October 2017 / Revised: 10 November 2017 / Accepted: 13 December 2017 / Published: 20 December 2017
(This article belongs to the Special Issue Sound and Music Computing)
Wavefolders are a particular class of nonlinear waveshaping circuits, and a staple of the “West Coast” tradition of analog sound synthesis. In this paper, we present analyses of two popular wavefolding circuits—the Lockhart and Serge wavefolders—and show that they achieve a very similar audio effect. We digitally model the input–output relationship of both circuits using the Lambert-W function, and examine their time- and frequency-domain behavior. To ameliorate the issue of aliasing distortion introduced by the nonlinear nature of wavefolding, we propose the use of the first-order antiderivative method. This method allows us to implement the proposed digital models in real-time without having to resort to high oversampling factors. The practical synthesis usage of both circuits is discussed by considering the case of multiple wavefolder stages arranged in series. View Full-Text
Keywords: acoustic signal processing; circuit modeling; nonlinear waveshaping; antialiasing; synthesis; music acoustic signal processing; circuit modeling; nonlinear waveshaping; antialiasing; synthesis; music
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MDPI and ACS Style

Esqueda, F.; Pöntynen, H.; Parker, J.D.; Bilbao, S. Virtual Analog Models of the Lockhart and Serge Wavefolders. Appl. Sci. 2017, 7, 1328.

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