• Eurorack MiniMod with Keyboard
  •    Vintage DNA - Eurorack Power

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AJH Synth MiniMod System

We have recreated what is probably the most epic and fattest sounding portable monophonic synthesiser of all time and adapted it to the Doepfer Eurorack modular synthesiser format. First and foremost the MiniMOD had to replicate the sound of the vintage Model D as closely as possible, so we have used exactly the same internal circuitry and every module runs at the same internal signal and control voltage levels as the original.

The MiniMod is based on the circuitry of most desirable Model D of all, the very early R A Moog Mk1 model with its unique and sweet sounding VCO design, the core of which uses discrete transistors only, with no integrated circuits. We have also based the transistor ladder VCF on the early design, which uses fully matched transistors throughout. Less than 300 Mk1 Model D’s were built with this very early VCO design out of a total of around 17,000 which were produced between 1970 and 1981.

The Minimod has been more than 18 months in development, thousands of hours have been spent analysing the original Model D using both real world measurement and computer based Spice circuit simulation programs, we have carefully selected components and built many prototypes before we were happy that we had done justice to the original sound and circuit behaviour.

A Model D for the 21st Century?

Shown above - full MiniMod system installed into a Waldorf KB37 Eurorack Controller keyboard, this setup features 3 VCO's, 2 LFO's, Transistor Ladder Filter, 2 DH-ADSR Envelopes, 2 VCA's, Glide and Noise, Active buffer, Gain Switch Multi and keyboard offers Key Velocity, Aftertouch sensitivity, Midi Input and on board arpeggiator.



MiniMod Eurorack modules comprise separate VCO, VCF, VCA, Dual Contour and Glide/Noise for maximum flexibility so that they can be easily integrated into a larger Eurorack format Modular synthesiser to tap into the endless control and expansion possibilities – we have removed all of the control limitations of the “closed system” of the original Model D synthesiser so that the sounds that you can now create are limited only by your imagination and the other modules that you add to your system. All of the modules can be used independently in your existing Eurorack system – want to just try a VCF or VCA with your own modules? No problem, all of the modules are compatible with the most common Eurorack audio and control voltage standards and should integrate seamlessly into your system.

MiniMod modules are available in two styles, Vintage Black or Classic Silver. They are electrically identical, only the cosmetics are different.


We have added lots of extra features, if it was possible to add extra versatility without compromising the sound and functionality then we have done so.
Here are just some of the extra features that we have included:

VCO: - added External Sync (2 Types), Linear and Exponential Modulation, fully adjustable PWM instead of fixed  pulse widths and voltage controlled PWM. 

VCF: - added Voltage Controlled Emphasis using a vactrol and have added an extra overdrive capability, switchable using an internal jumper.

VCA: - added voltage control for each individual VCA (yes, the original design had two VCA’s in series!), along with an overdrive capability, switchable using an internal jumper.

Dual Contour: -  added individual  manual trigger buttons for both envelopes and envelope status LED’s

Glide + Noise: - added glide up only and glide down only modes in addition to the standard glide mode. We have also increased the range of the glide from the original 44 notes to 5 octaves.

 A MiniMod system would comprise 3 x VCO, 1 x VCF, 1x VCA, 1 x Dual Contour, 1 x Glide-Noise and this will take up 84hp of Eurorack space, so that it will fit into 3U of rack space with a suitable Eurorack frame and power supply (not supplied) Just add a Midi/CV converter and keyboard for a fully functional BIG and FAT monophonic synthesiser. Below is an example of how to patch a 3 VCO sawtooth sound with glide enabled on all VCO's.


New Modules added to the MiniMod range

The MiniMod system is undoubtedly the most authentic reproduction of a vintage synth available in Eurorack modular format, and it will faithfully re-create the iconic sounds of the Vintage Model D synthesiser - however, following requests from existing users we decided to develop a series of additional modules to hugely widen the range of sounds that can be created and take it well and truly into the 21st Century!

Firstly, we have introduced a new ADSR capable envelope generator to overcome the limitations of the original Contour Generators, along with adding extra Pre-Delay, Hold and retrigger options too. Then we added a compact Dual LFO and VCA module that makes it very easy to generate extra modulation without having to sacrifice VCO's or VCA's to this duty. Next, we have a versatile four channel Polarising CV Mixer which includes a voltage source, offset facility and VCA output stage - use it with the Dual LFO or any other modules as a CV mixer to create more complex modulations, or it can be used for level shifting and/or inversion of waveforms and voltages too.

Then we have the V-Scale Precision ajustable buffered multi, an excellent solution for interfacing other Eurorack modules with the MiniMod system and for solving more wide ranging and general Eurorack tracking and impedance mismatch problems. Lastly, we have the Gain Switch Multi, this allows front panel access to the internal gain jumpers on the MiniMod VCF and VCA modules, to add some extra grit and tube like distortion to your patches.

DUAL LFO / VCA: - Two LFO's with variable triangle and square waveshapes, including low range and sync/reset on LFO 1 and an onboard VCA. 

DH-ADSR Envelope: - Model D envelope characteristics but with full ADSR and additional Pre-Delay, Hold and Retrigger modes too.

CV Mix-Offset-VCA: - Four channel Polarising CV Mixer with +/-6V voltage source, input and CV offset facility and VCA

V-Scale Buffer: - 1 in 5 out precision active buffered multi with unique tracking adjustment facility on four outputs.

Gain Switch Multi: - Allows front panel access to the gain jumpers on the VCF and VCA, and includes a 6 way passive Multi.


A video review of the MiniMod system from Tiziano at SonicVoltage.com



Below is an example of how to patch the original MiniMod system for a 3 VCO fat sawtooth sound with glide enabled on all VCO's.

Ever wondered how obese the Model D would have sounded with five VCO’s instead of three? – Easy, add two more VCO’s and a mixer and you can patch it up. Do you want to have a triangle wave  LFO modulating  VCO 2  for vibrato while at the same time have a different frequency triangle wave modulating the PWM width on VCO 1? Easy, just add two Eurorack compatible triangle wave LFO’s and you’ve got it. How about cross modulating VCO2 with VCO3 and feeding back some of the output back through the filter to overdrive it? Or, how about mixing the sharktooth and PWM waveforms together from a single oscillator?– easy, just patch both VCO outputs into a mixer and patch the output of the mixer to the VCF. If you want to go further and crossfade between the two waveforms then use a Voltage controlled panner module and a triangle LFO or other modulation source instead. 

This is but the tip of the iceberg, the sonic possibilities are almost limitless in the Eurorack modular world!










Minimoog is a registered trademark of Moog Music Inc. We do not manufacture or sell Minimoog synthesisers.