Why build a (eurorack) modular synth?

A eurorack synth

Modular synths seem to be popping up everywhere, from interviews with big artists to synth YouTubers. They look impressive, but in these days of cheap and practically unlimited software synths, why are people turning to relatively expensive and cumbersome hardware?

I got into modular synths, and specifically Eurorack, about a year ago. I wanted to explore something new to get my ideas going, and it’s been interesting as I’ve been researching different modules online to see different views on why people get into this kind of equipment for music making.

While you are reading, take a listen to my latest release. A melodic techno atmosphere out now on Traum Schallplatten. This track started life as a live eurorack jam, and just had a bit of editing and added drums for the final version.

Any hardware gives a physical aspect to your music making, constructing sounds by tweaking knobs and performing timbre changes throughout a track. You can do this with a MIDI controller linked to a software synth, but somehow no manufacturer seems to have got to the immediacy of having dedicated hardware (except possibly in the area of DJ controllers, which are pretty dedicated in their function). I’ve used many MIDI controllers over the years, and although they can get the job done, mapping and remapping controls just isn’t the same as having a dedicated instrument that always responds in the same way. The patching aspect of modular synths adds a physicality to the deep creation of sounds that is often hidden under a menu even on many hardware synths.

There’s something really important to us about interacting physically with something to create music. When sound design is a huge part of your music, then being able to interact with that in a physical way can be really important. Software synths are amazing tools, but physical hardware feels like an instrument, something we have a relationship with rather than just use to create a desired effect and then move on.


Computers are great, but we use them for everything. There are so many distractions when you sit at a computer. Even if you avoid social media, games, or messing around ‘trying out’ plugin after plugin, sitting in front of a computer puts you in this mindset of multi tasking. Dedicated hardware puts you in the mindset of focusing on one thing, all it lets you do is be creative. It gives your constraints of course, but these can also focus your mind on bing creative and finding ways to work within them. I think many people find dedicated hardware like modular synths to give them a very different focus to the limitless possibilities of a computer.

Unique sounds

The previous points can be true for any hardware, but for some people the sounds you can get out of modular synths just can’t be got any other way. The controversy about analogue vs digital sound rages on, but for many people there’s something about analogue sounds that just speak to them on a very deep level. I’ve always been a bit on the fence with this one, but I have to admit being blown away by how you can push analogue hardware to behave in strange and out of control ways that very few digital or plugin synths seem to do (Uhe synths being one exception to this I’ve found). Can the listeners tell? I’m not sure this matters. Personally I think it’s more about the moment you get to when you are making music, how you get inspired by the sounds and what that leads you to create. You’ll make different music when you connect differently with the sounds. Not necessarily always better, but certainly different.

Then there’s the fact you can connect modular synths in (almost) any way you want. There’s no LFOs hard wired to affect just a few parameters, you can send them anywhere. You can mangle signals, use audio to modulate parameters that it technically shouldn’t, run something through three filters instead of just one. It’s very flexible, and can be different every time. Your three oscillators and three filters could create one monster sound, or be used as three voices for different elements in your track. Once you get used to this it can be quite hard going back to a simple SH101 or Minimoog style synth where you get to a point that the possibilities stop.


This is the one that got me into modular synths- looking for something different to inspire me with new ideas. Building on the earlier points, I just wanted a different way of interacting with sounds, something I could turn to and shift into a different frame of mind than pulling up a plugin on my computer screen. This lead me to build a machine that could harness quite a bit of unpredictability (see the story of my synth to date here). I actually focused quite a lot on sequencing rather than sounds at first, which lead me to…

Thinking differently

I hoped to get results that were different, but I didn’t realise how much using a modular system would give me access to different processes. My setup using computer based plugins and virtual analogue hardware synths was very much based around the musical keyboard, and playing in or programming on a piano roll. On a modular system you can do this, or you can create much more process driven music that uses the routing and processing of signals to define the results that come out.

Feed and LFO into a quantiser and your have a musical phrase that can be dynamically shifted with the speed knob – a very different way of interacting with melodies. Plug something else in to modulate the speed, and you start to open up the world of complex phrases that are interdependent and even generative. The thinking you do to work in this way is entirely different to sitting in front of a keyboard or piano roll. Similarly different thinking can come in with sound design when you can choose to route signals in whatever directions you want to.


People joke about ‘Eurorocrack’, and there is something about a modular system that does seem to tap into a very deep seated urge to collect that many people have. Couple this with a market of module that is relatively boutique and dynamic producing modules that are sought after, hard to get, and constantly evolving and you have a potential collection compulsion that can get the better of your bank account.

I’m not sure this factor is entirely positive, but it’s definitely one of the reasons people get sucked into building these machines. In my experience a small number of modules can be a bit frustrating, as they are designed to be interdependent to get the most out of them. You do get to a point where each purchase can unlock more of many of the modules you already have, the possibilities start quite limited but increase exponentially. The trick is probably deciding when that exponential curve has increased your possibilities enough. Where that lies will be different for most people, but I’d say a 6U 104hp case that I have, if well planned out, can make a really flexible and interesting instrument that you can get a lot out of. You can always swap out modules if things become boring…

There are lots of good reasons why modular synths are an interesting tool to make music with. There’s not getting away from the fact that these machines cost money, and this can be hard to equate with the functionality of software. Looking at the specs in comparison it all looks a bit mad. Modular synths are definitely a luxury, but they are instruments that can add a lot to your process, and inspire very different ways of working, and hence very different musical output. If this has got you interested I highly recommend having a go with the free VCV Rack virtual Eurorack, or if you have Reaktor trying out the ‘Blocks’ platform.

Do you have other reasons why you got into modular synths? Let me know in the comments, there must be many I haven’t thought of.

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