Relations in modular

Hello everyone !
I am kind of new in the modular world and digesting a lot of concepts. I just want to expose to you all my lasts thoughts, thinking that you may have a lot of intersting things and reference to add.
The thing that hit me the most in eurorack, is that each module is only a mechanism, with a certain range (ex: an oscillator, with a frequency range) but the mechanism don’t have a define fonctonality, it’s the relationship (an output to an input) with an other mechanism wich define it (ex: an oscillator modulating an other create a vibrato, a new timbre with audio rate to fm or sync, a two note melody from the square output, etc…). All the magic of the modular coming from the fact that un mechanism can have multiple relation at the same time, thus creating multiple fonctinality, and may have an input and an output relationship, maybe with the same module (feedback).

I stumble across maths from time to time, and relation are really interesting, this site list some kind of mathematical relations in a set, and it’s easy to make a connection with modular patch, is every thing connected ? Is each voice carefully serparated ? Where are the relation, where is there no relation, where are the border of each cohabitating systems?

I am still struggling a bit to understand the category theory and all the implication of the Yoneda Lemma. But I think there are things to find here.

All of this are budding thoughts, enough of my vision, what are yours !


One of my main draws to eurorack is that patches - and voices - are often interrelated. They interact. They affect each other. They evolve together. In a purposeful way, with endless possibilities. Couple this with the inherent need to design sounds from first principles, it leads to a more cohesive and deliberate sound (for me). Having said that, it does lend itself to more experimental composition styles. Utilising eurorack to make traditional voices (bass, lead, pad, etc) is certainly possible, of course, but it misses the point somewhat in my opinion.


A good friend who hadn’t seen my eurorack yet came over yesterday.

He’s got really good musical taste. But after about 5 minutes, he couldn’t endure the eurorack any more…

So, yeah, I guess I am not making normal music with it (yet)…


Haha yes, I hear you. Everything being interlinked can make some wild noises, which is part of the fun of course, but yeah - my experiments often end in that rather than music! its part of the appeal, I say. Not for everyone though

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One of the reasons I prefer to use several smaller cases with focused functionality is that it allows me to decouple parts of the system into disjoint units with limited, and clearly defined inputs and outputs. While I can cross patch arbitrarily, I typically don’t, and this tremendously reduces the connection permutation (and hence choice) space. This consequently makes it easier to reason about and hence use to reach a specific goal I have in mind.

For me, modular is interesting in that there is a strong overlap between the impacts of choices made on different time scales:

  1. Buying cases (longest time)
  2. Buying modules
  3. Arranging modules
  4. Patching
  5. Adjusting parameters (shortest time)

Each tier in this hierarchy affects the choices available in other tiers and hence your end results. Given the complexity of the process your experiences shape your choices resulting in an iteration which drives you somewhere. This drive might be toward a certain type of sound, or towards a certain case.

Despite being a mathematician (at least originally), I find less pleasure in analysis of mathematical viability or permutation space size, and more in a pragmatic approach to reaching my musical goals. The result is that I am intrigued by many concepts and thoughts what might further intellectualize my process, but I keep my distance from them. This is because a big part of my interest in music stems from the opportunity it affords me to go with what feels right. That being said, I’m very familiar with dynamical systems and the possibility to consider the behaviour of a modular system as such. Such approaches, for me, either end up too experimental (meaning offering insufficient control) or too intellectual (meaning offering a meta level of expression). Anyway, this isn’t exactly responding to your concept, but hopefully shares my higher order thoughts around that area of thinking.


I love doing some of that ! But due to fragile ear it quickly become painful, I would like to experiment more with “unpleasant” noise, but in a sense it’s soothing to cut a part of the universe of things that are possible to do. In the same way that sometime a

can be the route I chose after a long day of work and no more brain juce, just doing something pretty.

I tend to put the complexity of my patches in the modulation part, sometimes I barely know what’s happening, but I keep the sound source simple, so I have a good amount of control on the timbre
the concept of a trade between complexity and control is very interesting.
Thanks you all for your inputs !


Ha, I’d never thought about connecting category theory and modular synthesis. I suppose you could consider modules as the category and each Hom is a patch cable, but unfortunately I think that without other categories (objects in a daw?) and corresponding functors (what are the Homs in a daw? what would the functor from Euro to daw do for Homs?), it’s more of a fun thought experiment than anything useful. I wonder what the identity cable would be, and whether any arrows are invertible.

You certainly won’t run into set theoretic implications though… no worries about whether eurorack forms a set or not! It’s even a finite category – there aren’t too many of those lying around.

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In a way, I think fun thought experiments are always useful !
I don’t intend to use the category theory as a prism for eurorack (I don’t know each world well enough for that), but I like collecting ways of thinking about things.
Letting all the thoughts macerate in one big bowl, grabbing ideas here and there to form new patch ideas over a walk at the park.
It’s like searching for seeds, not knowing exactly what will grow…

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