ajh-synth/matrix-vcf
Matrix VCF
All-analogue multimode filter and VCA with 16 filter types selectable via knob or CV, two resonance models per type for 32 total variants, a unique P-Vox resonance distortion/overdrive circuit, and a hard-wired output VCA. Filter core is based on the Oberheim Matrix 12.984
Capabilities 3
- Multimode Filtermultimode-filter
- 16 distinct filter types selectable via MODE knob or MODE CV input, displayed by 16 LEDs; P-Vox switch doubles variants to 32.984
- Vcfvcf
- 16-type multimode filter core based on the Oberheim Matrix 12, with 32 total variants when P-Vox resonance mode is engaged.984
- Voltage-Controlled Amplifiervca
- Hard-wired output VCA with CV input normalled to +5V; Output Level knob acts as attenuator when external CV is patched.984
Jacks 9 (8 in / 1 out)
| Name | Signal | Voltage | Description |
|---|---|---|---|
| Inputs (8) | |||
| 1/3 Freq CV Input | cv | — | CV input for cutoff frequency tracking at approximately 3V/octave (1V per 0.33 octaves); can also be used as a general modulation input.984 |
| 1V/Oct CV Input | cv | — | CV input tracking 1V/octave for cutoff frequency control; enables use as a VCO when the filter is in self-oscillation, typically over a 3–5 octave range.984 |
| 2/3 Freq CV Input | cv | — | CV input for cutoff frequency tracking at approximately 2V/octave (1V per 0.66 octaves); can also serve as an additional modulation input.984 |
| Audio In | audio | -5V to 5V | Audio signal input; expected modular level is 10V peak-to-peak (±5V).984 |
| Freq CV Input | cv | — | External CV input for voltage control of cutoff frequency; level is set by the Freq CV Level attenuator knob.984 |
| Mode CV Input | cv | 0V to 5V | External CV input that selects filter type; MODE knob acts as attenuator. Accepts 0 to +5V (negative voltages cause erratic behaviour).984 |
| RES CV Input | cv | 0V to 5V | CV input for external resonance control; RES knob acts as attenuator. Accepts 0 to +5V; negative voltages treated as zero.984 |
| VCA CV Input | cv | 0V to 5V | CV input for the built-in VCA; normalled to +5V (VCA fully open) when unpatched. Accepts 0 to +5V; negative voltages are treated as zero. OUT LEV knob acts as attenuator when external CV is connected.984 |
| Outputs (1) | |||
| Audio Output | audio | — | Audio output from the filter and built-in VCA; level is set by the OUT Level control and optionally by external VCA CV.984 |
Parameters 7
| Name | Type | Range | Behavior |
|---|---|---|---|
| Audio Input Level | knob | — | Attenuates the audio signal fed into the Audio In jack; useful for balancing signal levels or reducing the input when the filter is self-oscillating.984 |
| Audio Output Level | knob | — | Sets the filter audio output level; also acts as an attenuator for the VCA CV input when an external CV is patched. Use with the Peak LED to optimize signal level.984 |
| Cutoff Frequency | knob | — | Rotating this control changes the filter cutoff/passband frequency.984 |
| Freq CV Level | knob | — | Attenuates the external CV signal patched into the Freq CV Input, controlling the modulation depth of the frequency CV.984 |
| MODE | knob | 1 – 16 | Selects filter type from 1 to 16; acts as an attenuator for the MODE CV input when a patch cable is inserted. Fully CCW = Mode 1 (4P BP), fully CW = Mode 16 (1P HP).984 |
| Res O/Drive Switch | switch | — | Up position (P-Vox off) uses the standard Matrix 12 resonance circuit; down position (P-Vox on) engages Polivoks-style resonance overdrive, forcing all filter modes into self-oscillation and producing harmonically rich waveforms.984 |
| Resonance Level | knob | — | Rotating clockwise increases resonance; at high levels some or all filter types self-oscillate. Acts as an attenuator for RES CV input when external CV is connected.984 |
Firmware history 0 versions
No firmware history recorded.
References 1
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[984]
AJH Synth Matrix VCF product pageproduct_page● verified 2026-05-26