The AJH Synths Matrix VCF & VCA is a 14hp Eurorack module offering an analogue, multimode voltage-controlled filter with 16 selectable filter types, 32 resonant filter variations, integrated VCA, CV control of multiple parameters, and inspired by the Oberheim Matrix 12 with added resonance distortion circuitry. Overview of the Matrix VCF & VCA The Matrix VCF & VCA from AJH Synths delivers an exceptionally versatile filtering solution for Eurorack systems, combining a highly flexible voltage-controlled filter with a built-in VCA. The filter core takes its design inspiration from the legendary Oberheim Matrix 12 synthesiser, offering sixteen distinct analogue filter types, surpassing the original's fifteen by introducing a unique four-pole all-pass phaser mode. The all-analogue signal path ensures rich, warm sound quality while maintaining precise control. Each of the sixteen filter types includes variants such as low pass, high pass, band pass, notch, all pass, and complex combinations of these, spanning from one to four poles. These can be selected manually via a front-panel control or modulated dynamically through CV input, with 16 dedicated LEDs providing instant visual confirmation of the active filter. Enhancing its sonic palette, the module features a unique P-Vox resonance overdrive circuit, allowing every filter type to enter self-oscillation and transforming resonance characteristics to produce harmonically rich, aggressive waveforms. This effectively expands the number of filter variants to 32, adding immense creative flexibility. Filter and Resonance Control Users can control the filter's cutoff frequency through manual knobs and multiple CV inputs, including 1V/octave, 2V/octave, and 3V/octave tracking, allowing precise tuning or modulation from external sources. The resonance can also be controlled manually or via CV, with the P-Vox switch enabling Soviet-style distortion for all filter types, forcing self-oscillation even in modes that would not typically support it. The self-oscillating waveforms vary by filter type, offering more complex alternatives to traditional sine waves, and tracking reasonably well across three to five octaves for use as an oscillator. User Interface and Controls The module's interface is designed for clarity and ease of use despite its extensive functionality. The front panel includes controls for cutoff frequency, resonance, filter mode selection, input and output levels, and CV attenuation. Audio signals are fed into a level-adjustable input, with a peak LED indicating output signal levels above 10V p/p, ensuring optimal signal management without distortion. The output section includes a hard-wired VCA, controlled either manually or via external CV, enabling users to shape dynamic levels without needing additional modules. Built-in VCA Functionality The inbuilt VCA, while neutral in character, provides practical signal level control without introducing additional harmonic coloration. When no CV is patched into the VCA input, it remains fully open, allowing manual volume control through the output level knob. When a CV is present, the output level acts as an attenuator for the incoming signal, offering dynamic amplitude modulation directly from the filter's output. Specifications The Matrix VCF & VCA occupies 14hp of Eurorack space, with a depth of 29mm including the power cable. It consumes 56mA on the positive rail and 36mA on the negative rail. Available with silver or black fascia options, it offers exceptional build quality in line with AJH Synths' standards, delivering a compact yet powerful filtering and amplitude control solution.
