WDF Modeling Of A Korg MS-50 Based Non-Linear Diode Bridge VCF

Maximilian Rest, Julian D. Parker, Kurt James Werner

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (Scopus)
410 Downloads (Pure)


The voltage-controlled low-pass filter of the Korg MS-50 synthesizer is built around a non-linear diode bridge as the cutoff frequency control element, which greatly contributes to the sound of this vintage synthesizer. In this paper, we introduce the overall filter circuitry and give an in-depth analysis of this diode bridge. It is further shown how to turn the small signal equivalence circuit of the bridge into the necessary two-resistor configuration to uncover the underlying Sallen-Key structure. In a second step, recent advances in the field of WDFs are used to turn a simplified version of the circuit into a virtual-analog model. This model is then examined both in the small-signal linear domain as well as in the non-linear region with inputs of different amplitudes and frequencies to characterize the behavior of such diode bridges as cutoff frequency control elements.
Original languageEnglish
Title of host publicationProceedings of the 20th International Conference on Digital Audio Effects
EditorsAlberto Torin, Brian Hamilton, Stefan Bilbao, Michael Newton
Place of PublicationEdinburgh, UK
Number of pages7
ISBN (Electronic)2413-6689
Publication statusPublished - 05 Sep 2017
Event20th International Conference on Digital Audio Effects - University of Edinburgh, Edinburgh, United Kingdom
Duration: 05 Sep 201709 Sep 2017
Conference number: 20


Conference20th International Conference on Digital Audio Effects
Country/TerritoryUnited Kingdom
Internet address


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