Starting a Eurorack Modular Synthesiser System: 7 Things I Learnt the Hard Way

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I’ve been tinkering with synths, sequencers and other gadgets for a long time now — writing about them for a few years too. ‘Going modular’ was always a thing that was going to happen eventually. Well, just over 2 months ago I finally got my first Eurorack modules. The time since has been an intense and exciting learning period, and a very rough time for my savings account. It’s a tricky world to navigate and get a handle-on before you dive in yourself, so here’s some stuff I’ve picked up that could be helpful if you’re looking at building a Eurorack modular system.

Control voltage offsets, attenuation, amplification & polarity.

Unlike MIDI, there’s actually no completely universal protocol for control voltages aside from a general agreement that tuning should be 1 volt per octave. The only absolute constant is the limitations of the 12v Eurorack power supply. So you get some CV outputs/inputs that do  -5V to +5V, some that are 0v to 5v and some that are 0v to 10v. 

This is pretty annoying really, if you send an LFO that’s bipolar (say -5v to +5v) to a CV input that only responds to 0v to 5v, then that’s half your LFO that’s being cut off and not doing anything. Lame. So! In that scenario, you’d need a module that can attenuate the voltage to -2.5v to +2.5v, then offset the voltage to only be positive: 0v to 5v. Utility modules like Attenuverters and Offset generators are unexciting, unsexy and still cost money/rack space…but unfortunately they’re necessary, so put some money aside for that.

Ya need triggers. 

I wasn’t setting out to make a percussion system so I didn’t really comprehend the importance of triggers. You need triggers to trigger envelopes, create clock signals, trigger quantizers, trigger sample/hold modules, reset LFOs — all sorts of things. If you’re interested in making self generating and/or evolving patches, then you need a way to keep everything in sync or it becomes a mess, so clock dividers, mults and logic modules are your friend for keeping everything sync’d. (unsync’d stuff can come later). 

Bonus tip: Off the shelf case and power solutions like Arturia’s Rackbrutes are great, but if you can find some second hand rails and power, building your own case is cheap and extremely easy, even for non-handy types like me (I used a hand saw and $15 sheets of plywood).

Utility modules can dramatically increase the creative possibilities of your system.

All the biggest “holy shit!” moments of my modular synth journey have been thanks to low-cost modules that take a control voltage signal and do something with it – not the audio focused modules. Unfortunately, this area of modular gear has the biggest learning curve as their names are fairly technical, or in the case of the biggest Eurorack manufacturer Doepfer, the explanations are primarily in German and not-so-amazing English. So I’m going to mention a few that I wish I’d gotten from the get go.

Ornament & Crime (o_C) is a collaborative open-source project by Patrick Dowling, mxmxmx, and Tim Churches, and is one of best modules out there for beginners in my opinion. It’s basically a little computer with a variety of software apps that change the module’s function. It’s a little difficult to explain in brief, and the overly technical language of the website is difficult to digest (not to mention the utterly unhelpful names for each app).  But a YouTube channel called Voltage Control Lab have done some good basic demos of a number of the apps, check ’em all out here.

A Pitch Quantizer is a module that takes a control voltage and spits it out in tune, ready to be plugged into an oscillator. For example, a standard triangle LFO wave shape would turn into a staircase shaped signal as the quantizer jumps to the voltage associated with the nearest semitone. It’s a really fun way to get ‘happy accidents’, the dynamic nature of a heavily modulated CV signal can make for an exciting stream of notes once quantized.  

A Precision Adder like the Doepfer A-185-2 is really fun way to combine CV sequences (or anything you like) to create more complex and longer sequences. I got two of these after watching the below video by Mylar Melodies, and I can confirm: it’s a very, very fun way to improvise sequences on the fly, particularly with something like a Korg SQ-1 or Arturia MiniBrute 2S.

An Envelope Follower module like the Doepfer A-119 is a simple way to bring an external drum machine into your rack and have it produce gates and control voltages along the way, meaning you have a gate signal that will follow whatever you do on the drum machine (or guitar or whatever) automatically. That’s a super easy way to mirror your drum machine’s swing on your modular system, or you could even mic up an acoustic instrument (or anything for that matter) and have its signal going through this module and into your rack for some weird sound design fun.

Your modular system doesn’t have to do everything.

There’s a serious temptation to keep adding more and more functionality to your rack. There’s so many possibilities out there, I’ve found myself forgetting that non-Eurorack gear exists. A few days ago I was contemplating adding some kind of audio looping solution and spent hours researching what’s on the market. The next morning I realised I already own a Korg Kaoss pad, an absolutely ideal unit for what I was wanting. (Facepalm).

Having a focus and system ‘purpose’ helps (and requires discipline), the beauty of modular gear is in the name — it can be whatever you want. An effects rig, a sequencing rig, a boutique analogue synth or all of the above. It’s totally up to you. (paralysis of choice anyone?)

Semi-modular synths are incredible value. 

Seriously. Some, like the Dreadbox Erebus v3 and Arturia Minibrute, also include extra utility modules in their patch bays — meaning more dollars in your pocket and more space free in your rack. There needs to be more of this kindness in the world. *Wipes tear*

Subtractive Synthesis is just the beginning.

 Modal Synthesis, Scanned Synthesis, Amplitude Modulation Synthesis and plenty more join ordinarily esoteric methods like Linear/Exponential Frequency Modulation Synthesis, Wavetable Synthesis, Granular Synthesis, Additive Synthesis and the complex waveshaping world of West Coast-style synthesis. Then there’s effects and modulation, I won’t go into them, but check out this module that literally uses radioactive Uranium to generate voltages...people are weird.

It’s really exciting.

I haven’t been this excited and obsessed with my music gear in a long time. Technically, I could achieve everything I’ve made with software instruments and Ableton Live, but the tactile experience of hands-on experimentation has led me down sonic pathways that I never would have thought of. That said, there are cons. I haven’t slept much. My wife has barely seen me. My social life is suddenly non existent. So if you’re gonna go down this path, get your affairs in order. 

The ever evolving rig as it stands today. AKA my happy place.

You can follow my modular musical journey via my ambient meanderings on YouTube here.

Finally, a shout out to these valuable resources for learning, inspiration and demos:

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