Modular synthesizers: dynamicity and interaction

Swiss Museum & Center for Electronic Music Instruments (SMEM)

Victorien Genna @smem

Framing modular synthesis within the broader context of electronic music production

Electronic music production is a jungle of methods, tools, traditions and obstacles that any musician has to navigate through. Since around the 1980s, sound synthesis has entered the computer world, giving any one with a computer the power to create sound at any of its layers: from emulating filters, to building sequencers, to designing full percussion sounds, up to the arrangement of entire pieces of music... and beyond. Much like many fields, it’s pointless to look for any particular “entry point” to sound design and music production: it is just a huge web of interconnected points of history that may repeat and even talk to each other. This rings true especially when one enters this world through the strange universe of modular synthesizers.

The Buchla 100

Let’s take a stab at the age-old question: what is a modular synthesizer? How one defines modular synthesizers depends largely on their needs and purposes. The very first modular synths used only the basic building blocks of synthesis, such as oscillators, filters and amplifiers. They were meant to give better access to the architecture of the instrument by allowing the musician to re-wire the elements freely, instead of making these choices in

the factory and soldering everything together permanently. This allowed for any new device, or widget, to be integrated in to the system. All it took was a handful of screws and a screwdriver. This sort of free-form instrument then became the terrain for the creation of entirely new tools. A couple rounds of standardization later and we have the Eurorack standard, set by synth-maker Doepfer in 1996, engulfing the majority of the market. This standard hosts a dizzying variety of makers, schools of thought, price ranges and purposes. Pioneer companies with huge production lines like Moog sit right next to couch- solderers and circuit-benders making one-off modules, 19th century tube amplifiers are used to distort digital FM signals from tiny computers just one row above. It’s a perfect jungle, where one can either create their own order or bathe in an inspiring form of chaos.

One key aspect of synthesizer modules is their cost. They average $200 a piece, and don’t really do much on their own. After that, comes the cost of creating space and allocating power for them. Creating a system that can play sounds on its own is usually a $2000 venture, at least. This prompts the question: why get into such an expensive way of making sounds? In this article, I would like to propose an answer to this question. This answer is coming from my own experience of building a modular system over the course of 4 years and learning about synthesis at many different levels: speaking to engineers, learning the basics of digital-analog emulation, creating my own instruments, tweaking those of others, and spending many hours behind my own synthesizer.

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Interactions & dynamicity

Electronic music, throughout its history, has featured plenty of paradigmatic sounds and riffs. The filter sweep of a Moog, the FM sounds of the Yamaha DX-7, the chromatic arrangement of sampled voices on a Fairlight CMI... Many people can instantly recognize electronic sounds, as opposed to organic ones. Why is that? Some might say that it’s because these sounds are unusual and new in terms of what humans are used to hear. But I want to argue that it’s because they are mostly static in their structure; the multiple elements they consist of don’t interact beyond some immediate links.

Yamaha - DX7, Yamaha, 1983, From the collection of: Swiss Museum & Center for Electronic Music Instruments (SMEM)
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Let’s take a look at some of the interactions that happen inside a guitar when it is played normally, say with a pick. The harder you strike a string, the brighter it might sound, and the longer it will ring for. There is interplay between the strings themselves if you pay close attention: they make each other resonate if they are carrying enough energy. The guitar

body acts as an amplifier, but you might also know that any closed space has one or more resonant frequencies that interact with the frequencies of the notes you are playing. It might be that tones around 900 Hz are a bit louder, and if these resonant frequencies are arranged in a harmonic manner, the entire guitar body is creating a tone that naturally supports the tones originating from the strings. This is really fun to think about, and I invite you to repeat this exercise with, for example, a piano.

This is what I call dynamicity in musical instruments. The entire object is a complex system of interactions and communicating elements, and simple changes in input method or energy have very distinguishable effects on the overall sound we hear. Synthesizers don’t sound synthetic because sawtooth and square waves don’t exist in nature, they sound that way because, by default, they create monolithic sounds that don’t add up to anything more than themselves. This fact is not new by any means, and many synthesizers have tried to find ways around it. A notable example would be with velocity-sensitive keyboards, which allow the musician to affect some qualities of the sound by varying the force with which they strike and press the keys. This information can generally be directed to a few different components of the sound, depending on the choices made by the designer of the instrument. But here we are again, dependent on the choices of someone else to play our music!

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The Yamaha CS-80, a synthesizer well known for the vibrant characteristics of its sound when using keyboard expression 

Making “Rube Goldberg” machines with sound?

You’ve probably already encountered a funny Youtube video where a complex contraption of objects cause other objects to move, fall or break in a sequential manner, like a very complex domino effect. These can be found by the dozen on the web and are very entertaining. They are sometimes called Rube Goldberg machines, after the cartoonist of the same name who would draw them in his animated films. If you’ve never heard of those, you should probably look up a few videos of them and come back to this article with them in mind.

Rube Goldberg's Self-Operating Napkin, From the collection of: Swiss Museum & Center for Electronic Music Instruments (SMEM)
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My point is that modular synthesizers can be used as Rube Goldberg machines, or platforms for building such machines. By giving the musician full voltage-controlled access to all the parameters, the modular synth becomes a unique instrument where simple sounds can result from deeply complex, hidden interactions. This, of course, requires number of utility tools such as signal multipliers, bipolar attenuators (attenuverters) and mixers. These elements allow the musician to branch out “causal sources”, vary the intensity of their effect, or combine the effects of multiple elements. To stop this from getting any more abstract, I will provide you with two examples: one written and explained, and the other briefly explained but illustrated via a patch file for the free modular software VCV Rack.

Example number one: with a very simple setup consisting of a keyboard, an oscillator, a low-pass filter, an amplifier and an envelope generator, let’s see how we can maximise the dynamicity of the system. I will assume that I have unlimited attenuverters, multipliers and signal mixers. Patch the keyboard pitch signal to inversely affect the filter cutoff, so that the lower the note, the darker the sound. Mix that in with the envelope, but attenuate the envelope, so that the filter only gets moved a little bit while the amplifier does the heavy lifting by getting the full envelope signal. Also patch in the envelope to the pulse-width modulation of your (square-wave) oscillator, with attenuation and offsetting to taste. You can also use your envelope to slightly affect the oscillator pitch, giving way to a more percussive type of sound. I could go on, but you probably get the idea by now: with just one envelope and a pitch signal, you can create a vast array of interlaced effects, totally out of reach on anything but a modular system.

VCV Rack - Dynamicity, From the collection of: Swiss Museum & Center for Electronic Music Instruments (SMEM)
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Example number two: In this FM-based patch, I’ve tried to create intricate connections between a larger amount of modules. Feel free to explore it yourself by turning knobs and adding connections! The essence of my argument is that modular synthesizers are the only instruments that fully allow the musician to be creative in the way they set up interactions between the elements. This is the main thing that your money buys when you splurge for modules: you are essentially buying a canvas where you are free to create deeply complex causal systems. Your role, as a modular synthesist, is to conjure up dynamicity. The cherry on top is that, with all the innovation and old patents being revisited, you are now able to introduce all types of technology into your “interaction network”. If you are getting in to this vast world and trying to figure it out, or if you feel like you have plateaued in your enjoyment of your modular system, I advise you to look at the modular venture through this lens from now on.

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