In Part 1 I talked about my reasons for entering the modular world and also where I’ve been gathering my information to get started. In this article I’ll talk a little about the basic things I’ve learnt as a complete novice and my first steps towards assembling a case. There is no doubt that on the surface Modular Synthesis can look too hard to delve into, but the more you talk to experienced users and research the clearer things become. I’ll try to impart some of the basics to help get you started. I am still learning about modular synthesis so please keep that in mind if you are a more experienced user reading this article, this is entirely my perspective as someone new to the modular world.

My modular is going to be Eurorack format, I touched on why I selected this format in the previous article – the small size, affordability and large selection of modules were the primary reasons for choosing this format.

Eurorack Module Specifications

Eurorack format calls for modules of 128.5mm height. The height is referred to as “U” and one module is 3U high (3U = 128.5mm).

Horizontal width is measured in “horizontal pitch”, where 1 HP = 5mm.

3.5mm phone jacks are used for interconnection or “patching”.

Eurorack requires ±12V power, in addition to +5V required by some modules. The format uses ribbon cables for power and a two-row ribbon cable connector containing either 10, 12, or 16 pins. The 16-pin connector uses some of the extra pins to distribute control voltage and gate signals from a keyboard to the modules via a common case connection.

Eurorack Modules

If you visit some forums like the Muff Wiggler forum you will come across plenty of people asking the question “what do I need to get first?” or “what is the best basic setup to start with?” – there will no doubt be pages of debate between seasoned modular users about how you should begin. The truth is it really depends on what you want to achieve, you need a plan.

Because you are assembling your unit from scratch you can take it in any direction you want, maybe you want to replicate your favourite vintage synth or explore drones or drum machines, or perhaps you are interested in creating an effects unit for processing audio. Your goal will decide how you begin. I want to add another synthesiser to my setup as I feel my noise sources are currently a little limited. So this is the direction I’ll explore in this series of articles.

To start off, I had a look at my current hardware synthesisers and the various sections that help generate and shape the sound, this provides a direction for the type of modules you will need when assembling a modular synthesiser, things like Oscillators, Filters, Envelopes, LFO and some controls to help shape or sequence the sound. Here are some common terms you will come across as you start to shop around for modules, I’ve included the Wikipedia definitions but don’t worry if they don’t make a lot of sense at this stage! I’ve put some notes under each one about what it does in simple terms.

  • VCO – Voltage Controlled Oscillator, a continuous voltage source, which will output a signal whose frequency is a function of the settings. In its basic form these maybe simple waveforms (most usually a square wave or a sawtooth wave, but also includes pulse, triangle and sine waves), however these can be dynamically changed through such controls as sync, frequency modulation, and self-modulation.
    Translation: It is a sound source, it produces sound.
  • LFO – A Low Frequency Oscillator may or may not be voltage-controlled. It may be operated with a period anywhere from a fortieth of a second to several minutes. It is generally used as a control voltage for another module. For example, modulating a VCO will produce frequency modulation, and may create vibrato, while modulating a VCA will produce amplitude modulation, and may create tremolo, depending on the control frequency. The rectangular wave can be used as a logic / timing / trigger function.
    Translation: It makes the sound move or turn on and off.
  • VCF – Voltage Controlled Filter, which attenuates frequencies below (high-pass), above (low-pass) or both below and above (band-pass) a certain frequency. VCFs can also be configured to provide band-reject (notch), whereby the high and low frequencies remain while the middle frequencies are removed. Most VCFs have variable resonance, sometimes voltage-controlled.
    Translation: It shapes the sound by cutting or accentuating highs and lows.
  • VCA – Voltage Controlled Amplifier, is usually a unity-gain amplifier which varies the amplitude of a signal in response to an applied control voltage. The response curve may be linear or exponential. Also called a two-quadrant multiplier.
    Translation: Modular Synthesisers don\’t have a volume knob, so this is what controls how loud a signal is.
  • Mixer – a module that adds voltages.
    Translation: It takes a bunch of different signals (sounds) and mixes them together.
  • ADSREnvelope – Sound synthesis techniques often employ an envelope generator that controls a sound’s parameters at any point in its duration. Most often this is an “ADSR” (Attack Decay Sustain Release) envelope, which may be applied to overall amplitude control, filter frequency, etc.
    Translation: A VCO outputs a constant sound, so an envelope is used to shape the sound and decide how long it plays etc.

Essentially what you need to get started is a  VCO (something that makes noise) or multiple VCO\’s depending on your budget, and some modules to help shape and contour the sound into something musical. An entry level setup might look something like this:

  • Minimal setup: VCO + 1 VCF + 1 VCA + 1 ADSR + 1 LFO + MIXER
  • Better minimum setup: VCO + 1 VCF + 1 VCA + 2 ADSR + 2 LFO + MIXER
  • More advanced setup: VCO + 2 VCF + 1 VCA + 2 ADSR + 2 LFO + NOISE + RING MOD + 2 MIXER + SAMPLE AND HOLD

This will give you enough to start making sounds, from there you can add some of the wonderfully insane modules that developers are dreaming up to bend and twist the sound in seemingly unlimited ways.

Case and Power Supply

Another component you will need to consider is the kind of case/box you are going to mount your modules in, and how they will be powered. Cases can range from a simple wooden box (sometimes called a skiff or boat – a boat is slightly deeper) right through to more expensive flight cases that have built in power supplies. If you are starting out with a limited budget you will probably want an entry level kit like the TipTop Audio Happy Ending kit or you will take a DIY approach and build your own. I decided to take a DIY approach and build a wooden case to fit my specifications.

The main things you will need to build your own box are some modular rack rails (also known as Z Rails – TipTop Audio also manufacture these) and a power supply. There are some great module based power supplies available to power small cases and make setup easy for us newbies. The important thing is to ensure that it is +12V with +5V available as a lot of new modules (particularly digital) require this. Power Modules simply mount onto the front rails like a standard module and have a “bus board” that runs through the back of your case allowing around 10 modules to be connected.

I opted for the TipTop Audio uZeus as a lot of people seem to use them with very few complaints. Because the uZeus is designed to power smaller modular’s I decided to use 104HP rails (528.3mm) and make it a single row of modules (3U) – this info allows you to work out the internal measurements you will need to mount the rails correctly (where 3U = 128.5mm). How the case  looks outside of that is entirely up to you. I was fortunate enough to have some solid Rimu wood available so my case is built entirely from this.

Module Brands

There are some amazing modules out there and some really innovative companies producing them, so what modules should you get? I took some time to check out the main companies making Eurorack modules  (You can check out a short list in Part 1) and watch the demo videos and/or audio demos that are available on most of their websites. YouTube is also a great resource, if you find a module that peaks your interest then search for it on YouTube so you can see some examples of it in use.

I stumbled across Mutable Instruments when I was doing my initial research and their modules really stood out as being innovative and creative, something that would help me achieve a great sound. They also tend to be multi-functional and contain hidden features so you can do a little more with them. I took the plunge and ordered a few of their modules to get started, my first case will be primarily filled with Mutable Instruments modules but I’d like to expand it with some TipTop Audio, Harvestman and Make Noise modules in the future – when you go modular it seems to become a life long obsession/sickness so so I have no doubt I’ll be building another box sometime soon.


Modular synthesisers use control voltage to trigger sound – you may also see this referred to as CV/Gate. You can use devices like the Arturia Minibrute, Microbrute or BeatStep or some of the Elektron range to send CV/gate signals or you can get a MIDI to CV converter and use your preferred Midi controller to play/sequence your modular. Hopefully my case will be ready in the next few days and I can start putting my modular together, this will be the focus of Part 3 in this series. Please feel free to ask questions or discuss anything I’ve talked about in the comments.

Posted by:Scott Brown

A creative type from New Zealand exploring sound and visual art.

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