Virtual analog Buchla 259 wavefolder

Fabián Esqueda, Henri Pöntynen, Vesa Välimäki, Julian D. Parker

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

4 Citations (Scopus)
88 Downloads (Pure)


An antialiased digital model of the wavefolding circuit inside the Buchla 259 Complex Waveform Generator is presented. Wave-folding is a type of nonlinear waveshaping used to generate complex harmonically-rich sounds from simple periodic waveforms. Unlike other analog wavefolder designs, Buchla's design features five op-amp-based folding stages arranged in parallel alongside a direct signal path. The nonlinear behavior of the system is accurately modeled in the digital domain using memoryless mappings of the input-output voltage relationships inside the circuit. We pay special attention to suppressing the aliasing introduced by the nonlinear frequency-expanding behavior of the wavefolder. For this, we propose using the bandlimited ramp (BLAMP) method with eight times oversampling. Results obtained are validated against SPICE simulations and a highly oversampled digital model. The proposed virtual analog wavefolder retains the salient features of the original circuit and is applicable to digital sound synthesis.

Original languageEnglish
Title of host publicationProceedings of the 20th International Conference on Digital Audio Effects
PublisherUniversity of Edinburgh
Number of pages8
Publication statusPublished - 2017
MoE publication typeA4 Article in a conference publication
EventInternational Conference on Digital Audio Effects - Edinburgh, United Kingdom
Duration: 5 Sep 20179 Sep 2017
Conference number: 20

Publication series

NameProceedings of the International Conference on Digital Audio Effects
ISSN (Print)2413-6700
ISSN (Electronic)2413-6689


ConferenceInternational Conference on Digital Audio Effects
Abbreviated titleDAFx
Country/TerritoryUnited Kingdom
Internet address


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