Pony VCF packs an entire voice output stage into an exceptionally narrow footprint, making it a powerful choice for compact performance racks. At the center of the circuit is the SSI2144 Fatkeys core, utilizing an improved ladder topology designed by Dave Rossum. This design choice delivers the warm, harmonically rich frequency response associated with vintage transistor filters while maintaining modern temperature stability and lower overall distortion when driven hard.

Unlike traditional ladder filters that suffer from a drastic drop in low-frequency volume when you increase the resonance, this module features automatic gain compensation. As you turn up the resonance control, the internal circuitry boosts the core signal to keep your low-end punch intact during high-Q sweeps. The input stage includes a three-channel mixer with dedicated slider faders, allowing you to blend multiple oscillators or noise sources directly before the filter stage without needing an external utility mixer.

The module features a built-in VCA and an intelligent routing switch for the first CV input channel. You can select whether your incoming modulation controls only the filter cutoff, or if it simultaneously opens both the cutoff and the VCA. This normalled behavior lets you patch a single envelope into the module to create a fully articulated synth voice, saving you patch cables and external modulation utilities.