How I Started to DESIGN A Eurorack Module


I now have a monophonic Eurorack synthesiser that I am able to sequence; it can produce a wide variety of tones and I am looking to expand the system further. However, I am finding that specific utility modules such as mixers or active buffers are often extremely expensive considering how simple the circuits are and how cheap the components are to make them. In light of this - I have set out to solve some basic problems I am having as someone who has a limited budget but who wants to continue to expand and explore the Modular world.  

The first problem I have begun to tackle is that I do not have a clock source within my Modular system; this is mainly due to finance for now, but also because until recently the only clock sources I needed were for external sources to my Modular system; the PO-12 drum machine and Korg Volca Keys which both clocked together easily using one cable. With the recent addition of the Turing Machine to my system I have discovered that the clock signal from both external devices is not strong enough to use with my Modular and so I need to boost the signals coming from them in order for them to be useful.

In order to help me achieve this I have purchased a number of books by author Douglas Self to make this process easier - these books cover topics from basic electronics to common implementations of components and amplifier and crossover design using practical and theoretical examples. I intend to start with some basic op-amp circuit designs and work my way up to sample and hold circuits and then to LFOs and VCOs. The focus of this project being budget DIY Eurorack module design for people like me just getting into Modular for the first time.

Audio Power Amplifier Design
By Douglas Self
Small Signal Audio Design
By Douglas Self
The Design of Active Crossovers
By Douglas Self

Thus far, the concept for the first module will take the stereo output of the PO-12 and split it into two mono signals with individual amplification per channel allowing me to separate the clock from the audio. This is beneficial for me in that it will allow me to connect a common stereo TRS cable to the modular and from this point use usual patch TS cables (in the past I've been using less common TRS to dual TS (for left and right) cables). I already know that I'd like this module to be as small as possible; roughly 4HP (20mm) - this will allow me to get the most out of my modular case as possible.

More updates to come at Really Nice Audio.

Elliott Liu