Virtual analog models of the Lockhart and Serge wavefolders

Fabián Esqueda*, Henri Pöntynen, Julian D. Parker, Stefan Bilbao

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
280 Downloads (Pure)


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.

Original languageEnglish
Article number1328
JournalApplied Sciences (Switzerland)
Issue number12
Publication statusPublished - 20 Dec 2017
MoE publication typeA1 Journal article-refereed


  • Acoustic signal processing
  • Antialiasing
  • Circuit modeling
  • Music
  • Nonlinear waveshaping
  • Synthesis

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