↑ EuroClack

Build Your Own Modular

EuroClack — the BYOM book and modules

Part of EuroClack.

Start your modular synth journey with this easy-to-follow and inspiring book. Inside a beautiful handmade binder, you'll find all the information and PCBs you need to construct your own mini Eurorack system. Ideal for beginners and experienced builders alike, this book guides you through the world of analog electronics, inviting you to try your hand at soldering while gaining valuable knowledge.

This is the webpage for the book. It contains an extended range of information to accompany the book, as well as a bit of information useful for those who want to find out more about what the book is about.

The Build Your Own Modular binder and PCBs
The handmade BYOM binder contains the guide and circuit boards for a complete mini modular system.

The finished system

Below is what the book creates: a mini modular Eurorack synthesizer that you can build on and use with other compatible Eurorack modules and systems. Click any active module in the system to jump to its section.

Low frequency oscillator module
Envelope module
Attenuverter module
Mixer module
Passive mult module
Microcontroller module
Power supply module
Voltage controlled oscillator module one
Voltage controlled oscillator module two
Voltage controlled filter module
Voltage controlled amplifier module
Passive mult module

Where to buy

Currently the only source is from Thonk, based in Brighton (UK). They can ship anywhere in the world and also provide a complete BOM to make life easier.

The Bill of Materials

There is a single bill of materials (BOM) for the whole project within the book. It is attached here for those that are interested, or so you can print further copies. The way it works is: for each module there is a sub-BOM that you use to select the parts needed from the main BOM. Here is an example of what one looks like — PSU BOM. Notice there are check boxes so you can tick off the parts you fit as you go along.

The parts can either be acquired with the purchase of the book or by sourcing them yourself. I have intentionally designed the system with very common, easy-to-find parts; unfortunately it will be impossible to get all the parts from the same place. I will try to keep this section up to date as much as possible, as the availability of parts is ever-changing.

Open source hardware

All the original module hardware files are available on GitHub to download and modify, or order for yourself. I offer no support with these files, but I am happy to chat if you do. I am OK with them being used commercially — I only ask that you do not use my branding.

Press images

Would you like to post or print about BYOM? Please do! Below is a link to some hi-res images. Feel free to use any images or any other media on this website.

The completed BYOM system patched and powered on
The finished system is Eurorack compatible, so it can grow alongside other modules.

The modules

Below is a list of all the modules in the initial system. There are links to various helpers and details that did not make it into the book, plus items that are too dynamic for static pages, such as programming information and iBOMs — a handy interactive BOM generated by the InteractiveHtmlBom plugin for KiCad.

Power supplyMicrocontrollerVCOMixerEnvelopeLFOAttenuverterPassive multVCAVCFEnclosure

Power supply

BYOM power supply module
Power supply

Creates a simple ±12V power supply from a single 12V DC input. Suitable for building the system without having to spend lots of money on a DC-DC converter part. Contains short-circuit protection in the form of polyfuses, and LED indicators to show the rail status.

Microcontroller

BYOM microcontroller module
Microcontroller

A Raspberry Pi Pico-based module that lets you program all sorts of different functions and experiments. Supports simple-to-use languages such as CircuitPython and Arduino, but can also be programmed with more sophisticated lower-level languages. It has CV in, CV out, gate in and gate out connections, as well as two control knobs and two LEDs, all of which are user programmable.

Voltage controlled oscillator

BYOM voltage controlled oscillator module
VCO (two are included)

The main sound-generating part of the system; there are two of these, identical to each other. They generate a sawtooth wave and have a V/oct input, as well as sync in and out.

Mixer

BYOM mixer module
Mixer

This simple module mixes either audio or CV through 3 channels. The third channel, called "external", has 100× gain to bring up signals from line level or quieter.

Envelope

BYOM envelope module
Envelope

Attack and release envelope generator, simple as that. Puts out 10V envelopes.

Low frequency oscillator

BYOM low frequency oscillator module
Low frequency oscillator

For basic vibrato and tremolo effects. Has a variable slope knob which is quite unique. Can output a pulse or a ramp simultaneously.

Attenuverter

BYOM attenuverter module
Attenuverter

For bringing the higher CV voltages down, inverting them, or both. There is also a knob-to-CV source if nothing is plugged into the input.

Passive mult

BYOM passive mult module
Passive mult

Simple unpowered module that fills a gap in the case, providing a simple way to split signals to multiple destinations.

Voltage controlled amplifier

BYOM voltage controlled amplifier module
Voltage controlled amplifier

A dual VCA based upon an OTA.

Voltage controlled filter

BYOM voltage controlled filter module
Voltage controlled filter

The main sound of a subtractive synth. 12dB/oct filter with low-pass and band-pass outputs. Two audio inputs for easy mixing without an extra module. Lots of "character" (aka distortion) and a very interesting resonance sound.

Enclosure

A low-cost way to mount all your modules and test them out, constructed from aluminium PCBs. Can be assembled with just a screwdriver, screws, a soldering iron and a tapping tool.

BYOM aluminium PCB enclosure
The low-cost enclosure is assembled from aluminium PCBs.