Modular synthesizers are in a resurgence period, and I'm not complaining. For a long time, they've captivated musicians with their unique analog sound and unparalleled tonal control.

However, even if their allure has piqued your curiosity, you might be left wondering how to effectively harness their power.

In this article, we will delve deeper into the practical applications of modular synthesis and take a closer look at the many components and techniques involved in the process.

Hopefully, by the end, you'll have a better understanding of how to navigate the world of modular synthesis and unlock its creative potential.

What Is a Modular Synthesizer?

In essence, a modular synthesizer is an electronic instrument that is made up of various modules, each serving a specific function, to generate sound.

Each of these unique modules is interconnected using sliders, switches, patch cables, and panels, giving players a wide range of connection possibilities.

The important thing to understand here is that there are typically two main types of signals:

• Audio - The signal that represents the final output sound
• CV (Control Voltage) - The signal that controls various parameters of the modules.

And if you're sitting here thinking,

"This is already sounding complicated..."

Don't worry.

Before we get super deep into the weeds, we'll familiarize ourselves with the necessary terminology.

First, however, let's explore where modular synthesis came from.

A History and Evolution of Modular Synthesizers

The origins of modular synthesis can be traced back to the late 1950s, when German engineer Harald Bode developed the first hardware unit.

A decade later, the iconic Buchla Modular Electronic Music System and Moog synthesizer were introduced. You've likely heard of Moog before.

This one-of-a-kind synthesizer consisted of separate modules that generated and shaped sounds, including filters, noise generators, envelopes, sequencers, and more, all of which were interconnected using patch cords.

When the 1970s rolled around, the Japanese company Roland sent shockwaves into the modular community with the release of the Roland System 100 in 1975. They would continue following this synth up with the System 700 in 1976 and the System 100m in 1979.

Roland had effectively expanded the possibilities of modular synthesis and brought new sonic capabilities to the burgeoning frontier.

However, the dominance of modular synthesizers in popular music began to wane as the 1970s went on, as samplers, MIDI-connected gear racks, and highly integrated keyboard synthesizers rose to prominence.

By the 1990s, modular synth sales dropped even further, as more affordable and compact digital and software synthesizers emerged.

However, even with a clear cultural shift, there was still a dedicated community of musicians and enthusiasts who preferred the physically patched approach. It was the flexibility and unique sound characteristics offered by these traditional modular systems that they couldn't get enough of.

When the 2000s rolled around, there was a notable resurgence in the popularity of analog synthesizers.

With a wider availability of retro gear, lower production costs, and improved electronic stability and reliability, there was a renewed exploration of modular modules.

Now, with the development of virtual synthesis systems such as Reaktor, Pd, MAX/MSP, and VCV Rack, the resurgence is larger than ever before.

Understanding the Basics of Modular Synthesis

At the heart of modular synthesis is interconnectivity .

Unlike conventional synthesizers, modular instruments consist of multiple interchangeable components called (drum roll) modules.

Interestingly, modular synthesizers are easier to get a grip on than their non-modular counterparts, particularly when you start unraveling the fundamentals of synthesis.

With a modular synthesizer, you can visually and physically separate each component into distinct modules, giving you a better idea of how they function.

Now, while there are some modules available that offer a wide range of capabilities, most modules are designed to fulfill a specific role within the greater system.

I like to think of modules in a modular synthesizer as human organs. They each serve a different function for the body and are interconnected through a network of patch cables like our veins.

Let's explore the unique roles played by each component to get a better understanding.

Control Voltage (CV)

Control voltage serves as the communication medium between your system's modules.

As a result, many modular synth components are often described as "voltage controlled," such as a voltage controlled amplifier (VCA) or voltage controlled filter (VCF).

You can find CV inputs in modulation-ready modules. For instance, a filter module will typically feature a CV input you can use to control the cutoff frequency.

Oscillators

Without an oscillator, your synth simply cannot live and breathe.

The oscillator is the central component that imparts a distinct sound and timbre to any given synthesizer. Oscillators come in all shapes and sizes, though there are a few essential aspects to understand about them.

When it comes to modular synthesis, an oscillator's pitch is governed by the volts per octave (V/oct) standard. The oscillator will receive precise instructions through control voltage regarding the frequency at which it should oscillate to produce a specific musical note.

Without this V/oct control voltage, we wouldn't have accurate pitch control within the modular synthesizer system.

One unique thing about this level of pitch control is that modular oscillators allow for seamless transitions between western semitones and more atonal or half-tone sounds.

Lastly, it's important to note that modular oscillators typically generate sound in a continuous manner, meaning you need an amplifier and an envelope to govern the activation and deactivation of played notes.

While certain oscillators may incorporate built-in envelopes, gating the sound, this activation and deactivation is generally achieved using a separate module.

Filters

If you've ever produced or performed basic mixing or editing tasks, you may already have some familiarity with filters.

In the modular synth world, they're crucial.

Filters play a vital role in shaping the sound by selectively boosting or removing specific frequencies, just like you would with an EQ in your DAW.

The most common filter types include high-pass filters and low-pass filters .

High-pass filters allow higher frequencies to pass through while attenuating low frequencies, while low-pass filters permit lower frequencies to pass, while attenuating high frequencies.

That's not all!

Filters can also incorporate resonance, which is a feedback control that accentuates the center or cutoff frequency of the filter. Resonance is a wonderful tool for emphasizing specific frequency ranges.

Of course, if you already have a decent knowledge of basic synthesis, you likely understand the significance of filters when it comes to sound design.

Without them, you're limited to the range of sounds your synth can produce.

Amplifiers (VCAs)

Amplifiers are one of the simplest components in the modular setup, regulating the volume of the oscillator with control voltage and/or a volume knob.

In a modular synthesizer, however, amps have a primary function of acting as gates for the oscillators and other sound generators, giving players precise control over when the sound is heard or muted.

Amplifier modules are often compact and feature two or more VCAs.

For instance, the WMD Triple Bipolar VCA module offers three VCAs with bipolar control, allowing for both positive and negative amplification. Each VCA features dedicated control voltage inputs and 'attenuverters' for precise control over the audio signals. It also includes an option for cascading the VCAs, allowing you to cook up even more complex modulation possibilities.

Envelopes Generator (EG)

There are two significant roles that the envelope generator plays in a modular synthesizer setup.

For starters, it governs the volume of the amplifier with four essential parameters: attack, decay, sustain, and release. You've likely heard of ADSR before.

Each of these parameters determines the time it takes for the oscillator's signal to reach its peak volume, transition to a secondary volume level, and eventually decay to zero once the note is released.

Collectively, they shape the dynamic contour of any given sound.

ADSR is widely recognized as the standard modular synth envelope generator, though for those seeking more intricate modulation possibilities, there are also several other complex options available.

For example, you can use an envelope generator to modulate the filter's cutoff frequency.

The beauty of modular synthesizers lies in the rearrangement flexibility of the components, so an envelope generator could easily be repurposed to control an oscillator's pitch.

Modulation Sources

Beyond envelope generators, modular synthesizers offer a wide range of modulation sources for adding movement, variation, and dynamics to your sounds.

Modular synthesizers offer a wide range of modulation sources that add movement, variation, and dynamics to the sound. Three commonly used modulation sources in modular synthesizers are LFOs (Low-Frequency Oscillators), envelopes, and sequencers.

LFOs, or Low-Frequency Oscillators, are oscillators that operate at a much slower rate than audio-range oscillators., generating numerous types of waveforms, including sine, triangle, square, and sawtooth.

We primarily use LFOs for cyclic parameter modulation. With an LFO, we can affect the sound's pitch, filter cutoff, amplitude, and more.

Beyond that, they also provide an opportunity for adding rhythmic effects, such as vibrato and tremolo.

While LFOs are certainly a crucial modular synthesizer element, they're nowhere near as exciting as sequencers .

A sequencer is used to generate repeating and evolving control voltage or MIDI patterns. In modular synthesis, they provide precise control over the timing and sequencing of musical events, allowing players to create melodies, rhythmic patterns, and more.

Patch cables and Patching

Lastly, we need to have a basic understanding of patch cables and their routing, as these are fundamental aspects of modular synthesis that create the interconnection we've been discussing.

So, what in the heck are patch cables?

Patch cables are indeed actual cables with connectors (usually 3.5mm jacks) used to establish connections between modules.

They provide control voltage and audio signal transmission between the various components of a modular synthesizer. You can buy them in a wide array of lengths and colors too, which makes it easier to identify and organize the signal paths in your system however they make the most sense to you.

Building a Modular Synthesizer Setup

If you want to build your own modular synth, the format is the first and most important decision you'll have to make. Different formats offer unique characteristics, module availability, compatibility, and aesthetics.

Some of the most popular include Eurorack, Buchla, Serge, and Moog.

For the purpose of this article, we'll talk about Eurorack modules, as they're arguably the most popular.

Casing

Your modular synth system setup will begin with its enclosure or case. This is going to be the thing that houses the modules and provides power to them.

I highly recommend checking out the Doepfer A-100 LC1 if you're looking for a budget-friendly case, as it features an integrated bus board with eight module slots, allowing for the installation of multiple modules.

Plus, it comes with a power supply.

Basic Building Blocks

One of the most basic components of a modular system, whether it's for live performance or studio work, is the output. This piece establishes a connection between your system and your ears through an audio system.

At some point down the line, you might want to integrate external signals into your Eurorack setup. This is where input and output modules come into play.

I recommend checking out the Make Noise XOH Output Module for a good starter.

You'll find a relatively wide range of options available for sound production when it comes to Eurorack systems.

Subtractive sound synthesis is one of the most common synthesis types you'll find in these systems, which is great, as the subtractive voice process is the best one to start with when designing an initial modular system.

With subtractive synthesis, you'll often find oscillators that are routed through a voltage-controlled amplifier (VCA) into a voltage-controlled filter (VCF). LFOs and Envelopes are then used to modulate the overall sound.

One of my favorite units is the 4ms Ensemble Oscillator , which combines 16 complex oscillators and uses a combination of wavefolding, additive, FM, and phase-distortion synthesis for users to create unique soundscapes.

One of the last basic building blocks you need for sculpting your initial sound is a filter module. The market offers a wide variety of modules from various manufacturers, each with its own unique concept.

It's super important to closely examine and understand the functionality of these modules if you want to get the desired sound. Multimode filters, for example, like the extraordinary Waldorf VCF1 , have a particularly intriguing sound, all thanks to its numerous inputs and outputs, and its triple distortion-stage design (two stages of which have independent outputs).

Utility Modules

When working with multiple sound sources in a Eurorack system, incorporating a mixer is crucial. You'll want one with modulation inputs that can blend audio signals and control voltages.

Now, depending on the manufacturer, you might find additional functionality. One of my favorite modules is the ACL Gate Mix module, which offers a four-channel mixer with a voltage-controlled mute function.

It's incredibly sturdy in terms of construction and provides low-noise operation for the most natural, non-colored sound output possible.

You may also want to get yourself an attenuator to reduce the level of your signal passing through your system.

Attenuators are primarily used to adjust the amplitude or strength of a control voltage (CV) or audio signal, often providing a knob for dialing in the desired attenuation amount. These modules are useful for controlling modulation depth, adjusting signal levels to match other modules, and fine-tuning various system parameters.

I'm a big fan of the QUA Quad Attenuator from Rides In the Storm, which features individual signal paths for pre-defined or performative attenuation. For an inexpensive module, it offers a surprising amount of modulation control.

Modulation Modules

Modulation is what brings excitement into modular system. Without it, the various components of your system can't interact as they should, and you can't create the same level of dynamic and distinctive sounds.

Low-Frequency Oscillators (LFOs) and Modulators play a crucial role here.

One of the best modulator modules on the market today is the Erica Synths Modulator module. This versatile module provides a 2-channel LFO, eight selectable waveforms, and a noise source. You can easily blend the eight waveforms together, giving you a wide range of shaping options, depending on your preferences.

Next, you'll want a module to shape the envelopes in your synth. This is where envelope generators come in.

With the right one, you can unlock highly distinctive sounds in your modular system.

One of my favorites is the Mutable Instruments Stages Segment Generator, which functions as a six-stage envelope or an ASR (Attack-Sustain-Release). You can also use it as a four-step sequencer and an LFO (Low-Frequency Oscillator) for even greater modulation versatility. The evolving sonic possibilities with this retro little unit are near endless.

Of course, no modular synth is complete with a sequencer.

A good sequencer opens you up to more diverse melodic and rhythmic structures. Luckily, you'll find a wide range of sequencer options available, leaving no shortage of potential experimentation.

The Doepfer A-155 is somewhat of a class, delivering reliability and functionality with two rows of switches, each of which has eight steps. And if that feels limiting, note that it can be expanded further with the Doepfer Sequencer Controller A-154.

Effects Modules

Modular system effects are the spices and sauces in your modular synth recipe, offering unique character and flavor.

As with digital effects of stompbox effects, each effects module brings its own distinct texture, offering fresh creative possibilities.

For example, the Radikal Technologies RT1701 EFFEXX module offers a dual multi-effect, eight-algorithm design with a gorgeous-sounding reverb processor. The animated stereo effects that you can get from this unit are nothing short of captivating.

On the other hand, you have the Softube Clouds by Mutable Instruments , which offers a broad range of virtual effects, such as a granular effect that splits the input signal in real-time into up to 16 grains, allowing you to manipulate the size, texture, density, pitch, and position of each.

From physical effects modules to virtual effects modules, you have an extensive selection to pick from, so I recommend first considering the genre you often work in and the specific effect or effects that best complement your artistic vision.

Final Thoughts

Stepping into the world of modular synthesis can feel overwhelming, especially for beginners. Even experienced users may find it daunting at times.

However, I find that, comparatively, modular synths offer a fun and fulfilling experience, giving you the chance to create distinct sounds while providing a better understanding of the fundamentals.

With the right kind of research, you can embark on the right path to start building a truly remarkable modular synth that will provide you with countless years of enjoyment and boundless creative possibilities.

Take your time when exploring and learning about modular synths. As with anything in music, if you take time to embrace the discovery process, you'll get a better grasp on the vast potential that modular synthesis has to offer.