AJH Synth-Matrix VCF

Sixteen filter modes with dual resonance personalities, inspired by the Oberheim Matrix 12 and pushed into new territory.

Matrix VCF takes the rare filter topology of the Oberheim Matrix 12 and expands it into a compact Eurorack format. You get sixteen distinct filter types, each selectable manually or via CV, covering low pass, high pass, band pass, notch and complex combinations. AJH adds a four pole all pass phaser mode that was never part of the original design.

Each filter type features two resonance models. In standard mode, the response stays smooth, controlled and musical. Engage the P Vox switch and the character shifts dramatically. Inspired by Polivoks style distortion, this mode alters the resonance circuit, introducing grit, drive and more aggressive self oscillation. With P Vox active, all sixteen filter types can reach self oscillation, effectively doubling the palette to thirty two variations.

The layout stays clear and practical. Six primary knobs control cutoff, mode selection, resonance, CV depth and input and output levels. A row of sixteen LEDs shows the active filter type at a glance, which becomes especially useful when scanning modes with external CV. You can step through filter structures rhythmically or modulate them slowly for evolving textures.

Cutoff control includes a 1V per octave input, plus additional scaled inputs and a general frequency CV. In self oscillation, the filter tracks well enough to function as a sine based oscillator. Complex modes such as multi pole combinations create shapes that feel closer to fixed filter banks or vocal formants than standard subtractive filtering.

An integrated VCA on the output keeps patches efficient. With its own CV input and a peak LED for level monitoring, you can manage dynamics and drive without reaching for another module. Push the input harder for saturation, or keep it clean and precise.

Matrix VCF covers classic Oberheim style tones, but it also invites experimentation. Switching between structures under voltage control turns it into a moving spectral tool rather than a static filter.