Modular Synth

Modular synths are one of the most inspiring tools available to electronic musicians today: synthesizers that you can assemble yourself from core components, building an instrument specifically meant for your music and your workflow. These core components, called modules, each perform an individual function. ModularGrid is a database for modular synthesizers with an integrated planner where people gather information and sketch out their modulars. There are 10928 Eurorack modules to choose from. Users build 326858 Racks in this universe.

Modular synth is taking over the world.

This once uncommon synthesis type has become the main arena for sonic experimentation in electronic music—and beyond.

Modular synthesis has a rich history that dates back to the earliest electronic instruments. And its flexibility and versatility are second to none.

But getting started with modular isn’t easy. It’s complicated and expensive with a steep learning curve.

Even so, it doesn’t have to be intimidating. The sound design possibilities of modular synthesis are incredible, so it’s worth it.

In this guide I’ll go through everything you need to know to decide if modular is for you and how to take your first steps.

Let’s get started.

What is modular synthesis?

Modular synthesis is an open-ended approach to synthesis in which different modules in a customizable system are interconnected using physical patch cables. Each module in a modular system is specifically designed to carry out a single synthesis function, allowing them to be patched freely into any part of the control or audio signal path.

If that sounds technical, all it really means is that modular synths have no set architecture and can be set up in any way you want.

Here’s what Joey Blush has to say about his experience with modular synths. You can find his sample pack which was made entirely with his extensive modular synth on LANDR Samples.

A post shared by LANDR (@landrmusic) on

This open patching system comes from the original sound synthesizers developed in the 1960s by Robert Moog and Don Buchla.

It’s hard to imagine now, but at the time synthesis was an abstract academic concept without much practical use in music.

Synths weren’t quite considered instruments the same way we’d think about them today. They were more like massive electrical terminals operated by technicians.

Over time, musicians and synthesists developed the musical vocabulary for synthesizers and they began to appear in music outside the academy.

As synthesis matured, innovative companies like ARP realized that most musicians would set up their signal in a similar way each time.

That meant certain connections between modules could be patched permanently within the synth itself to save time and space.

Those developments gave rise to the synthesizer as we know it today with the introduction of the Minimoog in 1970.

The older approach took a back seat for decades until the modern modular synth renaissance kicked off in the late nineties with the introduction of the Eurorack standard.

Why get started with modular synthesis?

Modular synthesis has exploded in popularity thanks to how flexible and customizable modular systems and signal chains can be.

That means you can use whichever set of modules you prefer, in any configuration. There are a staggering amount of inspiring modules out there, with more being developed every day.

Modular rigs can create sounds that would be completely impossible on even the most flexible integrated synths.

Modular rigs can create sounds that would be completely impossible on even the most flexible integrated synths.

It’s also a completely different way of thinking about synth patch design that focuses more on experimentation and unpredictability than strictly musical results.

If you’ve ever thought of yourself as a sonic mad scientist who’s more at home in a rat’s nest of cables than a traditional jam session, modular could be for you.

What is Eurorack?

Eurorack is the revolutionary standard that made the modern modular synth boom possible.

Before Eurorack, each synth builder had its own set of technical standards for their modules.

They were meant to be used in a complete system with other modules from that same manufacturer like in the old days.

Unfortunately, that made connecting a bunch of modules from different builders basically impossible.

As modular became more popular, manufacturers realized these closed systems were stifling both business and creativity.

Eurorack was developed to standardize the basic requirements for module designs.

It standardized module features like dimensions, jacks, power requirements and signal levels for control and audio alike.

Now, every builder involved in Eurorack benefits from the vastly expanded pool of customers and modular synthesists get to build highly personalized rigs using whatever equipment they can get their hands on.

That spirit of cooperation reminds me of another legendary standard that brought electronic music manufacturers together once upon a time…

Control voltage

There are two types of signal flow in a modular synth.

The first is simply the audio signal that you eventually hear through your speakers when you connect your modular rig to an audio interface or mixer.

The second is called control voltage and it’s the signal that handles all the other duties inside your modular.

That means everything—even basic functions like triggering notes on the keyboard!

Once you wrap your head around this you’ll see how processing control voltage separately using modules of your choice greatly expands your synthesis possibilities.

You’ll start to think of sounds and signals differently too.

There are many modules that specialize in manipulating the electrical properties of the signal. What happens when you invert the polarity of a control signal? How about scaling it up or down?

Learning how these properties affect the sounds you make is another exciting perk of diving into modular.

Cases and power supplies

Every modular synth rig is built completely from scratch.

That means you even have to buy the power supply and case that you’ll put your modules inside.

You might think the case is a trivial detail, but the model you choose will inform a lot about your system.

You might think the case is a trivial detail, but the model you choose will inform a lot about your system.

How many modules will your rig contain? Will it be portable for live shows or more like a piece of handcrafted furniture?

Will it handle power hungry mega modules with ease or is it purpose built for lightweight components?

No matter what you choose, there are a few factors to consider.

Here’s what to know to buy your first Eurorack case:

  • The capacity of any modular case is measured in units called HP. It stands for “horizontal pitch.” One HP is 0.2” or 5 mm.
  • Modules are built to exact dimensions in HP. Each module has its own HP value that can be an even or odd number.
  • The total HP of your modules can’t exceed the maximum width of your case, so plan accordingly!
  • Most cases include the module mounting rails, but they can be purchased separately as well.

All those modules need power to run. Each module you add to your rig has its own requirements for current and voltage.


Many modular cases come with built-in power supplies, but some require to buy them individually or build them yourself.

Luckily, voltage requirements are standardized to either +/- 12V or 5V DC thanks to the Eurorack standard.

12V is common for analog components but as more and more digital modules make their way to the market, 5V is increasingly important. Make sure your power supply provides the voltage you need.

The current rating of your power supply determines how many modules you can use in your build.

Each module has a specific current draw measured in mA or milliamps. The total current draw of all your modules together can’t exceed the maximum your supply provides.

Most modern power supplies can dish out tons of juice but make sure you check in advance to make sure you don’t run out.


Here’s where the fun begins.

Choosing the modules you’ll add to your rig and customizing it to measure is a big part of the joy of modular synthesis.

Choosing the modules you’ll add to your rig and customizing it to measure is a big part of the joy of modular synthesis.

But it can be slightly stressful.

There are an enormous number of modules out there and the options are growing by the day.

Many experienced modular heads will tell you that the best strategy is to start with a detailed idea of what you want and realistic expectations for your rig.

Here’s a few tips for building your first modular:

  • Mixing and matching modules isn’t always user friendly. Stick to integrated synths for more practical synthesis duties and let modular be an experimental playground.
  • Polyphony is possible, but not essential. A flexible and inspiring modular system can be made up of a single voice only.
  • Don’t discount digital. Modular may seem like an analog-only world, but there are plenty of exciting digital modules that shouldn’t be overlooked.
  • The best modules might not even make sound. Effects, control devices and voltage manipulators are what make modular interesting.
  • Don’t forget a sequencer. Modular sequencers are extremely creative and often completely different from traditional ones.

Those are good ideas to start with, but don’t forget that there are no rules when it comes to modular.

The freedom to create any kind of system you want is the best part.

Modular mayhem

It’s easy to see why modular synthesis is growing so rapidly. The flexibility, open-endedness and spirit of sonic experimentalism make it incredibly appealing for adventurous musicians.

And thanks to the Eurorack standard, it’s only going to get better in the future.

Modular Synth

Whether you want to build your perfect custom rig or just go hands on with your patches, modular is an exciting development that every musician should know about.

Now that you know a bit about modular, start planning out the synth of your dreams.

Modular synthesizers are synthesizers composed of separate modules of different functions. The modules can be connected together by the user to create a patch. The outputs from the modules may include audio signals, analog control voltages, or digital signals for logic or timing conditions. Typical modules are voltage-controlled oscillators, voltage-controlled filters, voltage-controlled amplifiers and envelope generators.


A Moog 55 (c. 1972 to c. 1981)

The first modular synthesizer was developed by German engineer Harald Bode in the late 1950s.[1] The 1960s saw the introduction of the Moog synthesizer and the Buchla Modular Electronic Music System, created around the same period.[2] The Moog was composed of separate modules which created and shaped sounds, such as envelopes, noise generators, filters, and sequencers,[3][4] connected by patch cords.[5]

The Japanese company Roland released the Roland System 100 in 1975, followed by the System 700 in 1976 and the System 100m in 1979.[6]

By the 1990s, modular synthesizers had fallen out of favor compared to cheaper, smaller digital and software synthesizers.[6] German engineer Dieter Doepfer believed modular synthesizers could still be useful for creating unique sounds, and created a new, smaller modular system, the Doepfer A-100. This led to a new standard for modular systems, Eurorack; as of 2017, over 100 companies, including Moog and Roland, were developing Eurorack modules.[6]

Modular synth starter kit
A Doepfer A-100 (1995 to present)
EMS Synthi (VCS 3) II
Latest Fénix

Types of modules[edit]

The basic modular functions are: signal, control, logic/timing. Typically, inputs and outputs are an electric voltage.

The difference between a synthesizer module and an effects unit is that an effects unit will have sockets for input and output of the audio signal and knobs or switches for the musician to control various parameters of the device (for example, the rate of a chorus pedal) while a synthesizer module may have sockets for input and output, but will also have sockets so that the device's parameters can be further controlled by other devices/modules (for example, to connect an external Low Frequency Oscillator to a delay module to get the chorus effect.)

There exist many different types of modules. Modules with the same basic functions may have different inputs, outputs and controls, depending on their degree of complexity. Some examples include the Voltage Controlled Oscillator (VCO), which may have options for sync (hard or soft), linear or exponential frequency modulation, and variable waveshape; the Voltage Controlled Filter (VCF) that may have both resonance and bandwidth controls; and the Envelope Follower which may provide outputs at each stage of the process. Examples of more complex modules include the frequency shifter, sequencer, and vocoder.

There are some standards which manufacturers followed for their range of physical synthesizers, such as 1V/octave control voltages, and gate / trigger thresholds providing general compatibility; however, connecting synthesizers from different manufacturers may require cables with different kinds of plugs.

In the past, modular synthesizers were often bulky and expensive. Due to the continuously variable nature of knobs and sliders, reproducing an exact patch can be difficult or next to impossible. In the late 1970s, modular synthesizers started to be largely supplanted in pop music by highly integrated keyboard synthesizers, racks of MIDI-connected gear, and samplers. However, there continued to be a community who chose the physically patched approach, the flexibility and the sound of traditional modular systems. Since the late 1990s,[when?] there has been a resurgence in the popularity of analog synthesizers aided by physical standardization practices, an increase in 'retro' gear and interest, decreased production costs and increased electronic reliability and stability, the rediscovered ability of modules to control things other than sound, and a generally heightened education through the development of virtual synthesis systems such as VCV Rack, MAX/MSP, Pd and Reaktor etc.

Typical modules[edit]

Modules can usually be categorized as either sources or processors [7]

Some standard modules found on almost any modular synthesizer are:

Sources - characterized by an output, but no signal input; it may have control inputs:

  • VCO – Voltage-controlled oscillator, a continuous voltage source, which will output a signal whose frequency is a function of the settings. In its basic form these may be simple waveforms (most usually a square wave or a sawtooth wave, but also includes pulse, triangle and sine waves), however these can be dynamically changed through such controls as sync, frequency modulation, and self-modulation.
  • Noise source - A source that outputs a random voltage. Common types of noise offered by modular synthesizers include white, pink, and low frequency noise.
  • LFO - A low-frequency oscillator may or may not be voltage-controlled. It may be operated with a period anywhere from a fortieth of a second to several minutes. It is generally used as a control voltage for another module. For example, modulating a VCO will produce frequency modulation, and may create vibrato, while modulating a VCA will produce amplitude modulation, and may create tremolo, depending on the control frequency. The rectangular wave can be used as a logic / timing / trigger function.
  • EG - An envelope generator is a transient voltage source. A trigger in the presence of a gate, applied to an envelope generator produces a single, shaped voltage. Often configured as ADSR (Attack, Decay, Sustain, Release) it provides a transient voltage that rises and falls. It can be triggered by a keyboard or by another module in the system that produces a rapidly rising trigger in the presence of a gate. Usually it controls the amplitude of a VCA or the cutoff frequency of a VCF, but the patchable structure of the synthesizer makes it possible to use the envelope generator to modulate other parameters such as the frequency or pulse width of the VCO. Simpler EGs (AD or AR) or more complex (DADSR—Delay, Attack, Decay, Sustain, Release) are sometimes available.
  • Sequencer, also sometimes called an Analog Step Sequencer, is a family of compound module types which may be a source or a processor, see also below. As a source, depending upon the configuration, it may produce a sequence of voltages, usually set by adjusting values on front panel knobs. The sequencer may also output a trigger, and/or gate, at each step (stage). Sequencers are stepped by a trigger being applied to the trigger input. Designs may allow for stepping forwards or backwards, oscillating patterns, random order, or only using a limited number of stages. An example of an analog sequencer and controller with this level of complexity is the Doepfer A-154, A-155 combination.

Processors - characterized by a signal input and an output; it may have control inputs:

  • VCF - Voltage-controlled filter, which attenuates frequencies below (high-pass), above (low-pass) or both below and above (band-pass) a certain frequency. VCFs can also be configured to provide band-reject (notch), whereby the high and low frequencies remain while the middle frequencies are attenuated. Most VCFs have variable resonance, sometimes voltage-controlled.
  • VCA - Voltage-controlled amplifier, is usually a unity-gain amplifier which varies the amplitude of a signal in response to an applied control voltage. The response curve may be linear or exponential. Also called a two-quadrant multiplier.
  • LPG - Low pass gate, is a compound module, similar to a VCA and a VCF, except that the circuit uses a resistive opto-isolator (vactrol) to respond to the control voltage, which also filters the sound as it amplifies, allowing more high frequency information through at higher amplifications.
  • RM - Ring modulator - Two audio inputs are utilized to create sum and difference frequencies while suppressing the original signals. Also called a four-quadrant multiplier or balanced modulator.
  • Mixer - A module that adds voltages.
  • Slew limiter - Is usually a sub-audio lowpass filter. When used in a control voltage path to an oscillator, this can be used to create glide or portamento between frequencies.
  • S&H - Sample and hold, is usually used as a control-voltage processor. Depending upon the design, usually an ascending edge (trigger), captures the value of the voltage at the input, and outputs this voltage until the trigger input reads another voltage and repeats the process.
  • Sequencer, (see also above), as a processor, may have a signal input into each step, (location or stage), which is output, when stepped to. An example of this type of sequencer is the Doepfer A-155.
  • Custom control inputs - It is possible to connect any kind of voltage to a modular synthesizer as long as it remains in the usable voltage range of the instrument, usually -15V to +15V.

Modern manufacturers of modular hardware synthesizers (alphabetical)[edit]

Hardware offerings range from complete systems in cases to kits for hobbyist DIY constructors. Many manufacturers augment their range with products based on recent re-designs of classic modules; often both the original and subsequent reworked designs are available free on the internet, the original patents having lapsed. Many hobbyist designers also make available bare PCB boards and front panels for sale to other hobbyists.

  • Buchla Electronic Musical Instruments (formerly Buchla & Associates)
  • Doepfer Musikelektronik (A-100)
  • Moog Music (formerly Big Briar, formerly Moog)

Technical specifications[edit]

Form Factors[edit]

Many early synthesizer modules had modules with height in integer inches: 11' (e.g., Roland 700), 10' (e.g., Wavemakers), 9' (e.g., Aries), 8' (e.g., ARP 2500), 7' (e.g., Polyfusion, Buchla, Serge), 6' (e.g., Emu) and width in 1/4' inch multiples. More recently it has become more popular to follow the standard 19' Rack unit system: 6U (Wiard), 5U (8.75' e.g., Moog/Modcan), 4U (e.g., Serge), 3U (Eurorack).

Two 3U unit standards in particular are notable: Frac Rack (e.g., Paia), which uses the entire 3U for the front panel, and Eurorack (e.g., Doepfer) which has a 2mm horizontal lip that the front panels are seated between. Further minor variations exist where European or Japanese manufacturers round a U measurement up or down to some closer convenient metric equivalent; for example the common 5U modules are exactly 8.75' (222.25mm), but non-American manufacturers may prefer 220mm or 230mm.


Other differences are in the plugs used, which can match 1/4-inch or 6.3mm jacks, 3.5mm jacks, banana jacks, or breadboard patch leads,[8] in the main power supply, which is most often ±12 V[9]or ±15 V, but can range from 2.5±2.5 V[10]to 0±18 V for different manufacturers or systems, in the trigger or gate voltages (Moog S-trigger or positive gate), with typical audio signal levels (often ±5 V with ±5 V headroom), and with control voltages of volts/octave (typically 1 V/octave, but in some cases 1.2 V/octave.)

Most analog modular systems use a system in which the frequency is exponentially related to the pitch (such as 1 volt/octave or 1.2 volts/octave), sometimes called 'linear' because the human ear perceives frequencies in a logarithmic fashion, with each octave having the same perceptual size; some synthesizers (such as Korg MS-20, ETI 4600) use a volts/hertz system, where the frequency (but not the perceived pitch) is linear in the voltage.

Modular software synthesizers (alphabetical)[edit]

There are also software synthesizers for personal computers which are organized as interconnectable modules. Many of these are virtual analog synthesizers, where the modules simulate hardware functionality. Some of them are also virtual modular systems, which simulate real historical modular synthesizers.

  • Arturia Modular V
  • Moog Model 15

Computers have grown so powerful and inexpensive that software programs can realistically model the signals, sounds, and patchability of modulars very well. While potentially lacking the physical presence of desirable analog sound generation, real voltage manipulation, knobs, sliders, cables, and LEDs, software modular synthesizers offer the infinite variations and visual patching at a more affordable price and in a compact form factor.

The popular plugin formats such as VST may be combined in a modular fashion.

Semi-modular synthesizers[edit]

A compact semi-modular synthesiser

Modular Synth Power Distribution Vintage

A modular synthesizer has a case or frame into which arbitrary modules can be fitted; modules are usually connected together using patch cords and a system may include modules from different sources, as long as it fits the form factors of the case and uses the same electrical specifications.

A semi-modular synthesizer on the other hand is a collection of modules from a single manufacturer that makes a cohesive product, an instrument. Modules may not be swapped out and usually a typical configuration has been pre-wired. The “modules” are typically not separable and may physically be parts of a contiguous circuit board. However, the manufacturer provides mechanisms to allow the user to connect modules in different orders and often to connect external components or modules (chosen and supplied by the user) between those of the instrument.[citation needed]

Matrix Systems[edit]

Matrix systems use pin matrices or other crosspoint switches rather than patch cords.The ARP 2500 was the first synthesizer to used a fixed switch matrix.The pin matrix was made popular in the EMS VCS-3 and its descendants like the EMS Synthi 100. Other systems include the ETI 4600, and the Maplin 5600.

In digital times the clean logical layout of these matrices has inspired a number of manufacturers like Arturia to include digitally programmable matrices in their analog or virtual analog synthesizers.Many fully digital synthesizers, like the Alesis Ion, make use of the logic and nomenclature of a 'modulation matrix', even when the graphical layout of a hardware matrix is completely absent.

Patch Override Systems[edit]

The different modules of a semi-modular synthesizer are wired together into a typical configuration, but can be re-wired by the user using patch cords. Some examples are the ARP 2600, Anyware Semtex, Cwejman S1, EML101, Evenfall Minimodular, Future Retro XS, Korg MS-10 / MS-20 / MS-50 / PS-3100 / PS-3200 / PS-3300, Mungo State Zero, Roland System 100 and Moog Mother-32 .

Electronically Reconfigurable Systems[edit]

Reconfigurable systems allow certain signals to be routed through modules in different orders. Examples include the Oberheim Matrix and Rhodes Chroma, and Moog Voyager.

Modular Synth Fm

Hybrid modular synthesizers[edit]

Hybrid synthesizers use hardware and software combination. In alphabetical order:

  • Arturia Origin by Arturia (fully self-contained)
  • Clavia Nord Modular and Clavia Nord Modular G2 (these need an external computer to edit patches)

See also[edit]


  1. ^'8 of the most important modular synthesizers in music history'. FACT Magazine. 2017-09-21. Retrieved 2020-05-31.
  2. ^Lee, Sammy (3 July 2018). 'This is the early history of the synthesizer'. Red Bull Music. Retrieved 2019-11-02.
  3. ^Vail, Mark (2014). The Synthesizer. Oxford University Press. ISBN978-0195394894.
  4. ^Pinch, Trevor; Trocco, Frank (2004). Analog Days: The Invention and Impact of the Moog Synthesizer. Harvard University Press. ISBN978-0-674-01617-0.
  5. ^Kozinn, Allan. 'Robert Moog, Creator of Music Synthesizer, Dies at 71'. New York Times. Retrieved 2018-12-03.
  6. ^ abc'8 of the most important modular synthesizers in music history'. FACT Magazine. 2017-09-21. Retrieved 2020-05-31.
  7. ^Austin, Kevin. 'A Generalized Introduction to Modular Analogue Synthesis Concepts.' eContact! 17.4 ‹ Analogue and Modular Synthesis: Resurgence and evolution (February 2016). Montréal: CEC.
  8. ^
  9. ^
  10. ^

Further reading[edit]

  • Austin, Kevin - Introduction to the Analog Synthesizer (1984 - 2017), Concordia University, Montreal, Canada

External links[edit]

  • 120 years of Electronic Music has information on classic modular synths.
  • Resource for vintage synthesizer information and images.
  • Modular Analog Synthesizers Return! Article about new modular systems.
  • Modular Music TV Website dedicated to tutorials, news, performances and more using modular systems.
  • Generalized Introduction to Modular Analog Synthesis Concepts Article on modular analog synthesis concepts
  • Network of modular synth manufacturers and producers.
Mechanical specifications

Eurorack Modular Synthesizers

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