'rules' for building a eurorack system

i’ve started putting together a secondary / expansion case for my eurorack setup and that got me thinking about the internal rules i use to build a system that is interesting to me. it’s no secret that the growth of the eurorack format has led to both a diverse lineup of modules and an infatuation among many consumers to buy the newest modules; for anyone who feels stuck with their system or are wondering what they should buy or sell, hearing what rules we use to build our systems might help them out. all that said, i’m curious to hear what rules you adhere to. here are the ones i generally follow:

low rack space is critical for creating a focused instrument
no more than one oscillator per row (84-104hp)
cv sources/modifiers are more interesting than audio sources/modifiers
prioritize complete voices from a single manufacturer
keep menu diving to a minimum
no modules that can exist outside the system should be in the system (drum modules, passive modules)
whenever possible, put utilities in a 1u row
keep input/output ratios in check (eg, gate inputs to outputs)
if there are multiple cases, try to make each a standalone instrument

and here are my systems for reference

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My system is in constant flux, although the rate of change has slowed over the fast few years. I don’t really think about ‘rules’ I just put things where they make sense and swap things in and out as I feel like it. Looking at my rack, I guess I have ended up with sound sources at the top and sequencers/output at the bottom. Top-down workflow.

Cool topic! – over the last few years i’ve tried a lot of setups. I don’t sell my old modules, but I only use a max of 6u 84hp. At this point there are as many modules on the shelf as are in the system. It changes in and out a lot but never gets super huge, and that has helped me a lot I think.

Another key point for me:
I’ve moved away from trying to build a system design that is open enough to do anything, toward one that is limited to the type of music I like to try and make and the few things things that I do often. It turns out that this limitation is pretty extreme. The down side is the huge number of things I would like to do sometimes but I can’t. The flip side is that I don’t get lost, over patching crazyness very often – instead I have a lot of things prepatched that stay that way.

I’m not sure there is a difference, but I like to think of it more like a one off custom synth, than a eurorack modular, where anything is possible. Not sure if that makes sense.


Kinda the same here.

I did have to do a huge-ish rebuild a few days ago because my TT was not well aligned for long term staring. Was getting a cramp. Going to find an elbow-USB cable for it so that the cable isn’t in the field of view regardless of angle.

My set up is 3 x, perp, and 2 x, where perp is a row I’ve got at 90 degrees that serves as a central utility ‘spire.’ My OSC’s are generally in the back or middle-row-sides, and highly interactive stuff (Circadian Rhythms, etc.) in front. It is all mounted in the frame of an old drafting table, so I’m rather space constrained into the future.

But yeah, top down more or less, or maybe a little more like ‘upper corners to centre.’

i’m following your logic. this is the difference between designing an instrument and taking an everything but the kitchen sink approach.

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my #1 rule is space
fit within 72hp skiff and 42 overflow block

the smaller block is mostly passive utility so i can use it anywhere w/o power (if i choose)

my main rack used to flow left to right
rule #2 being: cv/gates toward audio & output

i’m rethinking how to get back to that somehow because last time I rearranged my rack i placed generators (teletype, earthsea, just friends) centrally

i think doing so might be personally counterintuitive


I have advocated for beginners to start with a cohesive system from a single mfg for a ‘voice’ and then figure out what works better over time. The thing about a modular is that you really do need all the parts for it to be whole. If you don’t know what you are doing (or just don’t have time to research) starting with a premise system makes perfect sense.

I also agree that small systems, or at the very least small cases, are the way to go. I disagree on the oscillator advice simply because sometimes that’s what you want vs filters or other functions.

“No battle plan survives contact with the enemy”
– Helmuth von Moltke

Just about my only rule is that I need an instrument I can move around easily. In practical terms this means something that can be taken as airline carry-on baggage.


I have this mental image of you in airline security with wires sprouting out of a suitcase, muttering german quotes.

My rule should have been to only buy things once I thoroughly understand the bits I already have. Alas.

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Understanding things is overrated. :smiley:

Naw, they didn’t care at LAX, though some of the passengers looked at me weird as I went down the aisle in the plane. Detroit TSA wiped it down and sent me on my way. I gotta say the huge bundle of patch cables in my backpack looked a lot worse in the X-ray than the modular.



That is an awesome case!!! Wow, you’ve inspired my weekend workshop project!

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i didnt start with subsynth voicing in mind (but understand fully why that would be wise for most)

at the time, i needed a flexible cv based companion to other external gear + tho i dabbled with many modules, i never had an osc and filter simultaneously until this yr

despite my original intentions, which are still priority, i’ve allowed it to become a self-sufficient performance instrument in it’s own right

Definitely! …and I think that is a common theme on lines especially. Within those bounds (instument instead of kitchen sink) you can also have a small powerfull and very flexible system – I think what i was trying to get out was that I’ve settled on quite a rigid system which has obvious flaws. It does get me in my electro-y hiphop mode pretty fast though, and these days thats on the top of my list.

Funny you mention starting out with utilities and interfacing with different instruments because my first module purchase was a Hexinverter MIDI/CV kit. I had no idea where to begin but figured I would need to have everything interconnected if I wanted to make music so that was, to me at the time, a logical place to start. Its sitting on a shelf now - seems like a waste.

Then I decided on building a Shared System one module at a time because I couldn’t afford to purchase one all at once. I think this very much shaped my outlook on modulars in general because that was my original vision (which I have yet to completely realize). I strayed along the way picking up various modules, mostly cheaper DIY, that served no other purpose than to tide me over until I could move the original project forward with a larger acquisition.

Now, I really think its all about keeping the approach in the forefront of the decision making and everything else is secondary. Then, for me, changing the approach after some time to see if what comes out still sounds like me.

It wasn’t until I discovered this place that I became much more intentional about my system and taking an instrumental approach to it. I think I’ve finally resigned to the fact that my modular is just fine being on its own and doesn’t have to be completely interconnected with my DAW or other synths in every way all the time. I can connect things on the fly for a temporary session or change up the layout (which I do often). For better or worse, I’ve accumulated enough gear over time to constantly keep me in a state of change for the most part when it comes to this. My modular cases stay fairly constant but how they get used changes often.

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I’d quite like to contribute to this thread but from a mainly non-eurorack modular perspective.
As the title specifically mentions eurorack I thought I’d check it’s ok to do so first.

(I appreciate sometimes people use the term “eurorack” to mean modular synth in the same way we use “hoover” to mean vacuum cleaner)


i attempted several times to build a modular that would cover every ground, a “universal” modular. this had two downsides - you could always find a way to improve upon a seemingly perfect setup so this meant it was never really done, and having a huge blank canvas did not inspire wild patching as i imagined it would, quite the opposite. often just putting 2 modules together in a small case sparks more synergy and generates more ideas than having a huge modular. but this is just a personal preference, different people have different patching style, of course.

so now i tend to keep a bunch of cases of different sizes and shapes and put it together based on some concept / experiment / specific patch i have in mind or as an instrument that makes sense. to me it’s also why i enjoy the process so much, it’s about discovering an instrument as much as designing it, you know you’re on the right path when the purpose of it suddenly comes into focus.

i’d love to hear non eurorack perspective as well - i think it’s interesting how the format itself shapes the “rules”!


go for it, discuss whatever you’d like. i specifically mentioned eurorack because that’s a significant focus of discussion here and that’s where my experience is.


I probably have more rules around my modular equipment now than I did at one time. But, it’s more to do with the systems as a whole and how they fit into the larger scheme of things.

So, with the exception of utilities such as VCAs/Mixers etc, I tend not to have too much duplication between systems, especially around oscillators. My Bugbrand (analogue oscs) is very different to my Modcan (digital fm oscs) which is in turn very different to my euro (no oscs!).

Within each system though I tend to like things to be pretty self contained. Each needs to work in its own right.

I also have a couple of small sidecar cases that I can use with any of the systems. One with some instrument interface type modules to bring external sound sources in. One with a couple of cv to midi modules. Doepfer minicases are great.

My main other rule these days is that none of these systems will get any bigger. As some of you know I am trying to downsize!

Rules and considerations might be a bit different when you get into something like Buchla. Although given the prevalence of clones now, there are more modules available than in the “just 200e” days which is what I have experience of. Then it was a case of picking a system from a relatively small range of modules. Not to say that it wasn’t a headache though - the same considerations around system balance, size and cost come into play whatever format I think. The good thing with Buchla for me was that as a format it really stopped those impulse buys that are all too easy in Eurorack. Real estate (and modules) although very fairly priced for what they are, were not cheap and much thought/saving had to go into the next piece of the puzzle.

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Apologies for the hopefully brief tangent. If one wants to explore Buchla in 2017, my understanding is that the ethical options are second hand, or DIY? The whole situation is sad and confusing, and tends to make me want to stay away, but on the other hand, I love the way Buchlas sound…

Essentially yes, second hand or DIY.
It does depend what part of the Buchla sound you are attracted to as to which of those two options might be the right one for you. I was really into the digital screwed up-ness of the 259e and not so much the “vintage” analogue stuff.
But can do a lot in Euro these days that would get you pretty close to either.
Of course you then have to take into consideration the interface itself which is one of the things that really sets Buchla apart from other formats.

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