I’ve finished my 6U Eurorack case. It took me 9 months to build, buying a couple of modules a month.

Goals

I wanted to make a self-contained dual voice synthesizer that would interface with my 2x Doepfer Dark Energy MK1s and my Microbrute, on a budget. I also wanted to add some random sound generation features.

I chose to make the synthesizer out of Doepfer modules because they are easy to find cheap second-hand, and also because they are well-engineered. (If they’re good enough for Kraftwerk, who am I to complain?)

Oscillators and Sound Generation

2x standard Doepfer A-110-1 VCOs with pulse-width modulation. I am no expert, but find these oscillators sound good enough for the money. A-118 Random Noise module, which outputs white and coloured noise. This has been useful for adding noise to a patch, as well as feeding the random noise generator through the quantizer and S&H modules for interesting random effects.

LFOs and Envelopes

A-143-3 Quad LFO, which has been very useful in modulating my external gear, such as my Microbrute and Doepfer Dark Energy synths. I find it’s a good utility module to just patch something up for modulation, even though I rarely find myself using all 4 LFOs at once. A-145 LFO – I actually find myself wishing this was a VCLFO so that I could make midi-synced LFO sweeps, and might replace it with one eventually. I like the reset feature though. 2x A-140 ADSR – Standard envelopes, I bought two so I can modulate the VCA and filter separately at the same time, as is standard in synthesizers.

Mixers and VCAs

A-132-3 Dual VCA – Another standard module, this is particularly useful as it has two VCAs, so I can feed each oscillator into its own separate VCA. I would like another one of these so I could amplify the output of the noise module separately from the VCOs. 2x A-138 Exponential Mixers – I have two so I can mix multiple waveforms from the VCOs with the white noise output from my noise generator module. The mixer in the bottom right corner of the case has rubber no-slip knobs, and I use it for the main output from my synth.

Quantizer and S&H

A-156 Dual Quantizer – This is a really fun module which I use with LFOs, envelopes and my noise generator to make musical sounds from non-musical sources. I think it will come into its own when I get the Make Noise Maths module, which is on my ‘next steps’ list. A-148 Dual Sample & Hold – This is a module I haven’t quite grasped the utility of yet, I currently use it wired up to filters and a LFO for S&H filter effects.

Filters

I love filters.. so I got quite a few!

A-120 VCF1 Low Pass Filter (Moog style) – The standard moogy filter, nothing wrong with it. I like the sound but mostly use it for filter sweeps. A-127 Triple Voltage Controlled Resonance Filter with Breakout Box – This is the key element of my setup. It allows for some really nice multiple filter chaining effects. I have the top filter set to ‘Low Pass’ mode, and the second and third filters set to ‘Band pass’ mode. Since I already have a LP filter in the Moog style A-120 I may change this back so it becomes a triple BP filter, which is the default. You can make some really nice patches with the inbuilt LFOs modulating the filter sweeps, but usually I will wire it up to my Quad LFO for modulation. As a unit, it is really good at making vowel-like sounds for eerie ‘almost human voice’ effects. The breakout box, which I haven’t soldered in yet, so haven’t actually used, will expand the possibilities of the unit even more, allowing me to put separate filers on each oscillator, for example. Love this module. A-106-1 Xtreme Filter – I haven’t used this much yet, but I just had to have the MS-20 style LP/HP filter in my case, and this filter ticks all the boxes.

MIDI Interface and Multiples

Kenton Pro Solo MIDI-to-CV interface – I use this with my computer, allowing me to send CV for the oscillators through the Intelligel Buff Mult. It has clock out and a bunch of different features, such as portamento and even a LFO. Intelligel ‘Buff Mult’ – My only non-Doepfer module. This is a buffered multiplier, meant to make sure that fast pitch changes are duplicated correctly over the oscillators. I also wire up my Doepfer Dark Energy Mk1s to this, so I can have 4 oscillators playing at once. A180-1 Multipler – Just a standard multiplier which I use because I don’t use stackable cables (can’t afford them).