Quad Operator a Variable Waveshape Operators for Linear FM Synthesis
A brand new eurorack unit made by Humble Audio. The Quad Operator is offering frequency modulation synthesis. You can watch more examples here at the companies Instagram site.

QUAD OPERATOR Features
- One knob per function design for true ease of use
- Any FM algorithm is possible via the 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
- The convincing digital emulation of classic analog waveshapes—sine, triangle, square, and saw
- An LFO mode enabled the generation of phase-locked, complex modulation signals
ALGO EXPANDER
There is also a expansion unit available. The Algo expander for the Quad Operator provides:
- 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
