Most electronic instruments consist of different functionalities tucked together under a surface of knobs, faders, buttons and the like. That, or the functionalities are hidden deep in software code. The end result is the same, in that you’re often left with an instrument inviting you to tweak. But what if you could separate these functions and recombine them in new ways to build your own signal path or instrument, and explore even deeper? You don’t have to be a West-Coast synth enthusiast or a code nerd to follow along here; there’s much to learn from the concept of modularity even for DJs, producers, and musicians of any kind.

Three levels of modularity

Most electronic musicians use a setup consisting of different plug-ins, hardware devices or effects units each performing a specific role. A particular synth may play the bassline, a drum machine is in charge of the beat, and the DAW is used for mixing while several plug-ins could be anything from effects to more synths, or samples. The one-person band is nothing new; it simply consists of a modular setup of devices. On this level, if you’re discontent with something, you simply may bypass or change the device to something more desirable.

Within an instrument, different parts such as channels, effects, or oscillators create options for the musician to work with the functionalities in the instrument or device. The first big modular systems consisted of separate units each carrying out their specific function (like the LFO, VCO, VCA, etc.). These functions are then patched together with removable cables. A mixer, for example, consists of different single channel strips, say 8, 16, or 24, and in a synthesizer, a separate module could act as a filter. On this level, you would want the device to be as flexible as possible in regards to features (for example several effect types), signal routing and updating – or ideally, you like every part of it as it is.

The third level of modularity is within the module itself. Within our example of the mixer, we have the single channel strip that consists of a volume fader, some EQ knob controls, effect send controls, buttons, and inputs. In the synthesizer’s filter, it may consist of a frequency control, resonance control, input, and outputs (for example high-pass, low-pass, and band-pass). On this level of modularity you don’t have to be content with the filter in your synthesizer or the EQ controls on your mixer; you simply take out that module and replace it with another that has the needed functions or features you desire – but of course; this requires the device to be modular.

Watch how the always innovative DJ and music maker Richie Hawtin created his show CLOSE – SPONTANEITY AND SYNCHRONICITY in true modular spirit.

A few words on signal flow

Before diving deeper into modularity let’s just get one thing straight; signal flow. Subtractive synthesis starts with the oscillators’ rich harmonic content, it is then mixed together, the mix is filtered, and then the sound is shaped with envelopes and other modulators. This signal flow is often visualized with everything from connecting lines and arrows and grouping of controls, to blinking LEDs and graphic displays illustrating a sound’s architecture. The key here is that we have a fixed routing based on a traditional approach. In modularity, this fixed routing is challenged and explored.

The grandfather of signal flow visualization is the original Minimoog, and with good reason: The oscillators go into the mixer, the signal is modified and then goes into the output. Nice and easy.

Conversely, it’s common in FM synthesizers to graphically illustrate the relationships of operators with diagrams – and other designs may utilize alternative signal flows. FM8 uses a modulation matrix for controlling the connections between operators and the amount of frequency modulation, as seen below:


Entering the matrix

The first prerequisite for some kind of modularity is that different functions can be combined in different ways to allow new routings of signals. For example, maybe you want to control not only the filter frequency but also the attack time of an envelope with the modulation wheel on your keyboard. In this situation, a modulation matrix is convenient; modulation sources on one axis and destinations on another. For fast, cable-free routing of signals or the conservation of space, a matrix offers a great deal of flexibility.
With the famous 16×16 matrix on the vintage EMS VCS3, the user makes connections by inserting pins. Color may be used to represent different resistor values and therefore varying signal or modulation amounts. Check out synth designer Tatsuya Takehashi’s walkthrough of the EMS VCS 3 in this video.

Putney (VCS3)

A modulation matrix for breaking or making connections between sources and destinations has become common in many contemporary synthesizers, for example with the Arturia MatrixBrute which provides a large modulation matrix in addition to the sequencing and patch selection functions of its 16×16 button grid.

Arturia Matrixbrute


Now that we have a signal flow and have messed with the matrix, we are ready to enter semi-modular synthesizers, which are often called ‘the gateway to modular’. They are standalone devices with the signal flow internally pre-patched or ‘normalled’. This means you can get results fast after having plugged the unit in. Via patch points, the conventional routings can be bypassed to reveal entirely new sonic territories.
The ARP 2600 is a semi-modular analog synthesizer designed by the late Alan R. Pearlman and Dennis Colin. Unlike other modular systems of the 1970s, the ARP 2600 has a fixed set of basic synthesizer components internally pre-wired. It was designed as two separate boxes: the synthesizer itself and the keyboard.

ARP 2600

Clear text labels and illustrative connection lines make it ideal for artists unfamiliar with analog synthesis to operate with or without patch cables. The ARP 2600, has been used by artists such as Stevie Wonder, Herbie Hancock and many others.

Semi-modular schematics

The Korg MS-20 analog synthesizer from 1978 groups all patch points to the right of the unit for convenient operation. They are arranged in the normalled signal flow illustrated on the surface. This method makes it very clear where the signal path may be interrupted or rerouted.

Korg MS-20

There are several options for hardware semi-modular synthesizers today, among them the Moog Mother-32, Make Noise 0-Coast, and the Korg MS-20 Mini – however, if you want something with a keyboard, the Moog Grandmother gets you started fast, and even supports the thought of modules by color-coding them on the front:

A semi-modular interface, whether in hardware or software, is a convenient and instantly rewarding way to enter the world of modular synthesizers – while learning about the generation, modulation, and routing of sound via a more easily understood interface.

The mojo of full modularity

Modularity is a flexible and highly efficient way of building things – just look at IKEA furniture or LEGO. One step further from the semi-modular world, the true modular mojo happens when we are able to completely separate or change the elements in our signal path. Say you don’t want a transistor ladder type of filter, then just change it to a SEM-style filter or a diode ladder filter, or you want seven sine waves instead of three? No problem, as long as you have the modules providing the functionality.

Modular systems are among the most fluid, complex and versatile electronic instruments. Typically the user can choose from a catalog of individual modules and position them, connect them and even replace them as needs demand. Naturally, this level of freedom has both pros and cons.

On the one hand, being able to assemble your own synthesizer with modules selected from several different vendors results in a completely unique and personal instrument. On the other, creating a manageable user interface from such diversity can be hugely demanding, especially for the inexperienced user. Even without the barrier of patch cords, a modular is rarely so readily committed to muscle memory as a fixed-architecture synth. Modulars come in both hardware and software forms and embrace everything from classic analog designs to innovative new ideas and technologies.

The world-famous composer and musician Tom Holkenborg, a.k.a. JunkieXL, includes his massive modular setup in many soundtracks, and is great at explaining his workflow: 

Kaitlyn Aurelia-Smith is also fascinated with modular synthesizers and uses the Buchla Music Easel for composing and performing. She says; “The feeling that I’m essentially an instrument maker by using modular synths excites me.” Check how she got into modular synthesis and “orchestrates” in the video below:

Modularity is one of the most inspiring ways to interact, interface, and intervene with musical instruments. For more information on modularity and modular systems check out PUSH TURN MOVE and PATCH & TWEAK.

Up next… Modular synth hardware formats and their distinguishing factors.

This article was part of a blog-series originally appearing at who kindly allowed us to repurpose Kim's articles again – here in a version edited by Collin Russel.