Quad Operator: Eurorack FM Made Easy, By Humble Audio

Who said FM synthesis has to be complicated? Humble Audio got in touch with us to announce the immediate availability of Quad Operator, a new, hands-on Eurorack module with 4 Variable Waveshape Operators for Linear FM Synthesis.

According to the company, implementing frequency modulation synthesis completely from scratch in firmware, the Quad Operator is able to provide a modern take on frequency modulation synthesis.


Main Features:

  • One knob per function design for true ease of use
  • Any FM algorithm is possible via modulation matrix
  • The Algo expander provides algorithm save/recall and crossfading capabilities
  • Independent output per operator
  • Virtual VCA per operator for both animating modulation and output volume control
  • Includes a dedicated “AR FM” input with its own modulation sends, designed to bring an audio rate signal in from your rack for use as a modulator. Try processing a phase locked operator, and feeding it back in!
  • Each operator can also be unlocked then tuned and patched independently, making the module a great general purpose oscillator bank
  • Convincing digital emulation of classic analog waveshapes—sine, triangle, square, and saw
  • An LFO mode, enabled the generation of phase locked, complex modulation signals

Price and Availability

The Quad Operator will retail for $500. Humble Audio also announced the availability of the Algo expander ($85) for the Quad Operator, which provides the following extra features:

  • Saving and loading of modulation send knob positions for FM algorithm design reuse
  • Crossfade between pairs of saved algorithms, or a saved algorithm and the live knob positions

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