Humble Audio is a San Francisco-based Eurorack module manufacturer that launched at Superbooth 2018 with its debut product, the Quad Operator. The 30HP module offers a modern take on DX-style FM synthesis, providing four variable-waveshape operators with sine, triangle, square, and saw emulations, a one-knob-per-function layout, and a modulation matrix that replaces traditional fixed FM algorithms with direct access to each modulation node.

The company also produces the Algo expander, a 4HP companion module that adds algorithm save/recall and morphing between two FM patches via a macro control. Each operator includes a virtual VCA for amplitude modulation and can be unlocked from the FM matrix to function as part of a general-purpose oscillator bank, and the module accepts audio-rate input through a dedicated AR FM jack.

With a narrow product line focused on making frequency modulation synthesis more approachable and tactile in a modular context, Humble Audio occupies a niche in the Eurorack market alongside other small-batch FM-focused builders. The Quad Operator has been reviewed favorably in synth publications including Synthtopia, Perfect Circuit, and macProVideo for its hands-on take on a synthesis style historically associated with menu-driven digital workstations.

Humble Audio has 2 products cataloged on Equipboard, including Modular Synthesizers. Their gear is featured by 1 artist, with the strongest followings in Electronic and Pop. Notable users include Andrew Huang.