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Modular Synthesizers - Beginner's Guide

Modular Synths Guide
Modular Synths Guide

Introduction to Modular Synthesizers

Welcome to the world of modular synthesis. It's much more straightforward to get started than you might think - here's our beginner's guide.

Modular Synths

By Naomi Macleod | Published 07.07.20

If you’re reading this, you’ve probably seen or heard modular synthesizers in action. You might be intrigued by the plethora of modules, sounds and effects that are on offer. It can seem overwhelming, even for those of us who have owned and operated hardware synths.

But fear not, getting into modular need not be a complex or expensive mission. We’re on hand to give you a basic introduction to this weird and wonderful world!

What is a modular synthesizer?

A modular synthesizer is an electronic instrument. A single module generally does a single job – using electronic components to either produce a sound or shape it in some way. When you combine several modules together, you can create a complete synthesizer and build your own bespoke instrument unlike anything else!

How does modular synthesis work?

Modular Synthesizers

Each synth module is made of discrete components (modules) that are connected and combined to create electronic sounds. Oscillators, filters, output modules, and mixers are just some of the more common modules you will come across when shopping for your first modular system.

Each module is designed to carry out a single function in synthesis, and when you combine many modules together you can create an unlimited range of sounds and possibilities.

There are two signals active in modular synthesis – audio and Control Voltage (CV). Audio is what we hear at the output stage, after the sound has been sculpted through the various module. CV is simply an electrical voltage used to trigger and automate parameters on various modules.

For example, if you connect a keyboard controller to a Voltage Controlled Oscillator (VCO) module using CV, the CV signal will increase and decrease with each key pressed. This same voltage change is then sent to the VCO, which will change its oscillating pitch. A Voltage Controlled Amplifier, or VCA module, then uses a CV signal to determine the amplitude of the audio signal.

This signal can then be sent through filters, envelope generators, effects and so on, creating the “patch” that we hear at the output. Modules are usually mounted together in a case or enclosure, powered by bus board, with CV signals transmitted via patch cables (either ¼” or ⅛” are standard: more on that later).

How does modular differ from a regular hardware synth?

Make Noise Black & Gold Shared System Plus
Behringer Odyssey Analog Synthesizer

A hardware synthesizer incorporates multiple components under one housing, all wired internally and ready to go. In contrast, a modular synthesizer is made from individual modules, giving you the freedom to wire them up in whichever order you like and change the signal path as you go.

Building a modular synth offers great flexibility - you can start small with a few modules, build up to a large system at your own pace, and change things around constantly. Not getting along with one module? Simply replace it and try something new. Need a new sound? Try a new patch order.

If you don’t like the flexibility of your hardware synth, you’re pretty much stuck with what you’ve got. With a modular setup, you change whatever you like and build your own instrument.

The CV signal is sent between modules using ¼” or ⅛” patch cables. Many still refer to presets on synthesizers as “patches”, stemming from this routing method.

There is a certain nostalgia, not dissimilar to that of vinyl records, to operating a musical instrument whose design has changed so little from its first iteration in the 1970s.

What is a semi-modular synth?

Korg MS-20 Mini Monophonic Analog Synthesizer

There also exists the semi-modular synthesizer – a combination of hardware synth and modular setup. A semi-modular synth is a standalone instrument that incorporates a patchbay. Out the box, a semi-modular synth is pre-wired internally and ready to go – just like a standard hardware synth.

However, if you add patch cables via the patchbay, you’ll bypass the internal connections and be free to connect things however you like. You can also patch audio in from an external source, such as a separate synth or sequencer.

Some popular semi-modular synths worth checking out include the Moog Grandmother, Behringer Neutron, and Korg MS20 Mini

Where did modular synthesis start?

The precursor to the modern synthesizer was first created in the 1950s - the RCA Mark II Synthesizer, developed at RCA Laboratories by Harry Olson and Herbert Belar. It wasn’t until the ‘60s that the first voltage-controlled modular synthesizer was built by Bob Moog and his team.

Moog-developed components - including the voltage-controller oscillator, sequencers, filters and noise generators - became standard across the synthesizer market. Unfortunately, the first modular systems were large, complex and priced out of reach for the consumer market.

By the late ‘60s, modular synthesizers started to appear in music studios, and became a hit with artists and groups who fawned over their exciting, avant-garde sounds. Over time, these systems became more compact and thus more accessible in price and functionality for the wider market. 

What do I need to get started with modular synthesis?

The good news is, you can start small and grow your modular system at your own pace, within your taste and budget. While modular synthesis is still a somewhat niche market, it’s becoming more standardised and popular in recent times – and therefore much easier to get started.

There are two specification standards that dominate the modular market today. Eurorack format, specified by Doepfer in 1996, is a compact, 3U format, thus fitting more modules per case.

The Moog-specified 5U format is an older, larger format, faithful to the dimensions of Moog Music’s original modular form factor. Eurorack utilises ⅛” patch cables, while Moog format uses larger ¼” connections. We’ve listed below some modules you might come across in a basic system.

What are the main modular components?

Here is a basic overview of modular system components. This list is by no means exhaustive, and there is of course a plethora of modules on the market beyond what we can include in one introductory article. It is often said that there is no “right or wrong” in modular synthesis - once you’ve created a basic system, the tweaking options are endless!


Doepfer A-100LC9 Case 9 HE PSU3

A case acts as both a secure enclosure and power hub for your modular system. The Doepfer A-100LC9 is an affordable case, complete with power supply, that will pack 3 rows of 3U modules.


Shop now | Doepfer A-100LC9 Case 9 HE PSU3

Midi to CV Generator

Doepfer A-190-2 MIDI-to-CV/Gate Interface (6HP)

For those looking to trigger notes via a keyboard, a MIDI to CV converter will convert and output your MIDI messages as Control Voltage. With four separate CV outputs for various MIDI messages, the Doepfer A-190-2 MIDI-to-CV-Gate Interface is a simple but versatile piece of kit for signal interfacing. You can than connect any MIDI controller and play melodies or tap beats.

Shop now | Doepfer A-190-2 MIDI-to-CV/Gate Interface (6HP)


Make Noise STO Voltage Controlled Oscillator (8HP)

This is the key module for generating sound. In basic terms, an oscillator is a waveform generated by a control voltage, with the pitch rising and falling as the voltage increases or decreases. A modular system can incorporate any number of oscillators, though in the case of non-modular hardware synths, we often see two, and sometimes three. Needless to say, the modular market has oscillators a-plenty.

The Make Noise STO Voltage Controlled Oscillator is a compact module, capable of sine, sub and variable shape outputs, giving you a canvas of different timbres to work with.

Shop now | Make Noise STO Voltage Controlled Oscillator (8HP)


Behringer System 55 904A VCF Module

Filters are the fundamental module that change the oscillating sound. A basic filter module will subtract harmonic frequencies, commonly via a low pass filter which cuts off frequencies above a set point. This is commonly seen on hardware synths and is an ideal filter type to introduce to your system.

The Behringer System 55 904A VCF Module is a simple low-pass filter which features both audio and CV inputs, enabling control of cutoff frequency from other modules, via control voltage.

Shop now | Behringer System 55 904A VCF Module


Doepfer A-140 ADSR Envelope Generator (8HP)

An Envelope controls the sound over time. On many envelope generators, the four factors of the ADSR (Attack, Decay, Sustain, Release) envelope can be individually shaped and sculpted, lending dynamics to a sound that now fades in slowly, or drops off rapidly after a quick attack.

The affordable Doepfer A-140 ADSR Envelope Generator does just this, and it includes an inverse output as well as standard and positive voltage, giving creative modulation options, depending on its connections to other modules.

Shop now | Doepfer A-140 ADSR Envelope Generator (8HP)


Erica Synths Drum Modulator (10HP)

Where an envelope gives dynamic to your sound, a modulator steps in to give it movement. An LFO (Low Frequency Oscillator) is a secondary waveform which, through operating at a far lower rate than the main waveform, can provide a pulse or sweep effect.

The simplest example of an LFO is a vibrato effect. This LFO frequency is usually variable in a modulation unit, and in the case of the Erica Synths Drum Modulator, features alongside two pitched noise sources and adjustable phase shift, giving you maximum swirling modulation capabilities.

Shop now | Erica Synths Drum Modulator (10HP)


4ms Listen Four Mixer Module (10HP)

A mixer module is a key component if you’re using multiple sound sources in your setup. Doing as it says on the tin, a mixer gives you control over individual source volumes, so you don’t end up with one sound dominant over others.

The 4ms Listen Four Mixer Module is a concise, compact 4-channel stereo mixer module, with handy pan options on channels 1 and 2, and a daisy chain option if you need to increase your channel count.

Shop now | 4ms Listen Four Mixer Module (10HP)


intellijel Steppy 4-Track 64 Step Programmable Gate Sequencer (8HP)

A sequencer generates a series of notes, voltages, or parameter controls in a set pattern. A sequence can provide a catchy melodic element to your track, and, depending on your modular system, be further modulated by effects and filters on either side of your signal chain.

Intellijel’s Steppy 4-Track 64-Step Programmable Gate Sequencer is a particularly powerful sequencer, boasting no less than four separate sequence outputs, making it a neat compositional tool for your system.

Shop now | intellijel Steppy 4-Track 64 Step Programmable Gate Sequencer (8HP)


Behringer System 55 911A Dual Trigger Delay

Effects are potentially the most exciting part of your modular sonic canvas. With options ranging from drives to delays, to bit crushers and beyond, there is endless fun to be had and choices to consider.

Behringer’s System 55 911A Dual Trigger Delay is a straightforward dual delay which can be run in parallel or in series. With both delay knobs ranging in time from 2ms to 10 seconds, you can achieve some pretty

Shop now | Behringer System 55 911A Dual Trigger Delay

Output Module

intellijel Outs, Balanced Stereo Line & Headphone Output Module (6HP)

Every modular system requires suitable connections at its final point in the signal chain. A simple output module will provide line and headphone outputs, so your system is headphone, monitor and record-ready at all times.

The Intellijel Outs Balanced Stereo Line and Headphone Output Module 6HP is almost as streamlined as they come, featuring stereo and headphone outputs, as well as a right-normalled input, meaning your mono input can still output as stereo.

Shop now | intellijel Outs, Balanced Stereo Line & Headphone Output Module (6HP)

Where next?

Whether you’re looking for individual modules, cases, patch cables, or even complete semi-modular systems, you’ll find everything you need here.

Shop now | Modular Synthesizers at Gear4music

Posted on 7 Jul 2020 13:54 to category : Instruments News

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