Modal Processor Effects Inspired by Hammond Tonewheel Organs

Kurt James Werner, Jonathan S. Abel

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
220 Downloads (Pure)


In this design study, we introduce a novel class of digital audio effects that extend the recently introduced modal processor approach to artificial reverberation and effects processing. These pitch and distortion processing effects mimic the design and sonics of a classic additive-synthesis-based electromechanical musical instrument, the Hammond tonewheel organ. As a reverb effect, the modal processor simulates a room response as the sum of resonant filter responses. This architecture provides precise, interactive control over the frequency, damping, and complex amplitude of each mode. Into this framework, we introduce two types of processing effects: pitch effects inspired by the Hammond organ’s equal tempered “tonewheels”, “drawbar” tone controls, vibrato/chorus circuit, and distortion effects inspired by the pseudo-sinusoidal shape of its tonewheels and electromagnetic pickup distortion. The result is an effects processor that imprints the Hammond organ’s sonics onto any audio input.
Original languageEnglish
Article number185
Number of pages18
JournalApplied Sciences
Issue number7
Publication statusPublished - 28 Jun 2016
Externally publishedYes

Bibliographical note

invited article


  • audio signal processing
  • modal analysis
  • room acoustics
  • signal analysis
  • artificial reverberation
  • digital audio effects
  • virtual analog
  • musical instruments


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