ajh-synth/minimod-vca

MiniMod Discrete Cascaded VCA

AJH Synth

A Eurorack VCA module with two fully discrete transistor VCA cores wired in series, modeled after the dual-VCA topology of the Moog Model D. Audio inputs and CV inputs control VCA 1; a Master CV input controls VCA 2, which is auto-normalized to full open when unpatched. An onboard jumper selects a high-gain overdrive mode for VCA 1.1017

Capabilities 1

Voltage-Controlled Amplifiervca
Two discrete transistor VCA cores in series with linear CV response; AC-coupled (audio signals only). Master CV auto-normalized to +10V when unpatched, keeping VCA 2 fully open by default.1017

Jacks 6 (5 in / 1 out)

NameSignalVoltageDescription
Inputs (5)
Audio 1audioFirst audio input summed into VCA 1; level set by the Audio 1 Level knob. AC-coupled; audio signals only.1017
Audio 2audioSecond audio input summed into VCA 1 alongside Audio 1; level set by the Audio 2 Level knob. AC-coupled; audio signals only.1017
CV 1cvFirst CV input controlling the gain of VCA 1 with linear response.1017
CV 2cvSecond CV input also controlling the gain of VCA 1; summed with CV 1.1017
Master CVcv≤10VControls the gain of VCA 2; auto-normalized to +10V when unpatched, keeping VCA 2 fully open by default (mirroring the external pedal normalization of the original Model D). Attenuation of the incoming signal is set by the Master CV Level knob.1017
Outputs (1)
Audio OutputaudioSingle audio output from the end of the cascaded VCA chain (VCA 2 output). AC-coupled.1017

Parameters 4

NameTypeRangeBehavior
Audio 1 LevelknobSets the input level of the Audio 1 signal into VCA 1. Turning to maximum increases distortion in overdrive mode.1017
Audio 2 LevelknobSets the input level of the Audio 2 signal into VCA 1. Turning to maximum increases distortion in overdrive mode.1017
Master CV LevelknobAttenuates the Master CV signal before it drives VCA 2's gain. When Master CV is unpatched, this knob acts as a manual master volume control (with the internal +10V normalization driving VCA 2).1017
OffsetknobAdds a manual bias/preset gain to VCA 1 independently of the CV inputs. Also affects distortion level in overdrive mode.1017

Firmware history 0 versions

No firmware history recorded.

References 1

  1. [1017]
    AJH Synth MiniMod Discrete Cascaded VCA product/manual pageproduct_page
    verified 2026-05-28