Modular synthesizer

Last updated

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) Moog Modular 55 img2.jpg
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. [1]

By the 1990s, modular synthesizers had fallen out of favor compared to cheaper, smaller digital and software synthesizers. [1] 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. [1]

A Doepfer A-100 (1995 to present) Doepfer A-100.jpg
A Doepfer A-100 (1995 to present)
EMS Synthi (VCS 3) II EMS at MIM Synthesizer.jpg
EMS Synthi (VCS 3) II
Latest Fenix Fenix II and III.jpg
Latest Fénix

Types of modules

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

Modules can usually be categorized as either sources or processors [6]

Some standard modules found on almost any modular synthesizer are:

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

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

Modern manufacturers of modular hardware synthesizers (alphabetical)

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.

Technical specifications

Form Factors

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, [7] in the main power supply, which is most often ±12 V [8] or ±15 V, but can range from 2.5±2.5 V [9] 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)

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.

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

A compact semi-modular synthesiser Korg Volca Modular 7921.jpg
A compact semi-modular synthesiser

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

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

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

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

Hybrid modular synthesizers

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

See also

Related Research Articles

Analog synthesizer Synthesizer that uses analog circuits and analog computer techniques to generate sound electronically

An analogsynthesizer is a synthesizer that uses analog circuits and analog signals to generate sound electronically.


CV/gate is an analog method of controlling synthesizers, drum machines and other similar equipment with external sequencers. The control voltage typically controls pitch and the gate signal controls note on-off.

Voltage-controlled filter Electronic filter circuit controlled with voltage

A voltage-controlled filter (VCF) is an electronic filter whose operating characteristics can be set by an input control voltage. Voltage controlled filters are widely used in synthesizers.

Buchla Electronic Musical Instruments

Buchla Electronic Musical Instruments (BEMI) was a manufacturer of synthesizers and unique MIDI controllers. The origins of the company could be found in Buchla & Associates, created in 1963 by synthesizer pioneer Don Buchla of Berkeley, California. In 2012 the original company led by Don Buchla was acquired by a group of Australian investors trading as Audio Supermarket Pty. Ltd. The company was renamed Buchla Electronic Musical Instruments as part of the acquisition. In 2018 the assets of BEMI were acquired by a new entity, Buchla U.S.A., and the company continues under new ownership.

Moog Concertmate MG-1

The Realistic Concertmate MG-1 is an analog synthesizer manufactured by Moog Music in 1981 and sold by Radio Shack from 1982 to 1983 under their "Realistic" brand name. It was produced without some standard Moog features, such as pitch and modulation wheels, as a cost-cutting measure aimed at achieving a lower price for the consumer market. The synthesizer also featured a pair of pass-through RCA jacks, which allowed users to mix radio or records into the final live synthesized sound output.

Moog synthesizer Electronic musical instrument

The Moog synthesizer is a modular synthesizer developed by the American engineer Robert Moog. Moog debuted it in 1964, and Moog's company R. A. Moog Co. produced numerous models originally from 1965 to 1981 and again starting from 2014. It was the first commercial synthesizer, and is credited with creating the analog synthesizer as it is known today.


The Multimoog is a monophonic analog synthesizer manufactured by Moog Music from 1978 to 1981. Derived from the earlier Micromoog, the Multimoog was intended to be a less expensive alternative to the Minimoog. It nevertheless had some advanced features which the Minimoog did not—most notably, it was one of the earliest synthesizers to feature aftertouch capability.


MOTM is the name of the modular synthesizer system manufactured by Synthesis Technology. MOTM stands for "Mother Of The Modulars".


The Memorymoog is a polyphonic electronic music synthesizer manufactured by Moog Music from 1982 to 1985, the last polyphonic synthesizer to be released by Moog Music before the company declared bankruptcy in 1987. While comparable to other polyphonic synthesizers of the time period, such as the Sequential Circuits Prophet-5 and Oberheim OB-Xa, the Memorymoog distinguished itself with 3 audio oscillators per voice and greater preset storage capacity.


The Moog model 2090 Micromoog is a monophonic analog synthesizer produced by Moog Music from 1975 to 1979.

Doepfer A-100 Modular synthesizer, introduced the Eurorack standard

The Doepfer A-100 is an analog modular synthesizer system introduced by German audio manufacturer Doepfer in 1995. Although it only had 10 modules at time of release, it currently has more than 120 modules plus several different enclosures and accessories.

Serge synthesizer

The Serge synthesizer is an analogue modular synthesizer system originally developed by Serge Tcherepnin, Rich Gold and Randy Cohen at CalArts in late 1972. The first 20 Serge systems were built in 1973 in Tcherepnin's home. Tcherepnin was a professor at CalArts at the time, and desired to create something like the exclusively expensive Buchla modular synthesizers "for the people that would be both inexpensive and powerful." After building prototypes, Tcherepnin went on to develop kits for students to affordably build their own modular synthesizer, production taking place unofficially on a second floor CalArts balcony. This led to Tcherepnin leaving CalArts in order to produce kits commercially, starting in 1974.

Synthesizer Electronic musical instrument

A synthesizer is an electronic musical instrument that generates audio signals. Synthesizers generate audio through methods including subtractive synthesis, additive synthesis, and frequency modulation synthesis. These sounds may be shaped and modulated by components such as filters, envelopes, and low-frequency oscillators. Synthesizers are typically played with keyboards or controlled by sequencers, software, or other instruments, often via MIDI.

Korg Mono/Poly Analog synthesizer, manufactured by Korg from 1981 to 1984

The Korg Mono/Poly (MP-4) is a 44 key "mono-polyphonic" analog synthesizer manufactured by Korg from 1981 to 1984. This keyboard is the sister synthesizer to the Korg Polysix. It has four highly stable voltage-controlled oscillators (VCOs), a 4-pole, self-oscillating low pass filter (LPF), wide modulation capabilities and pseudo-polyphony (paraphony).

Steiner-Parker Synthacon

The Steiner-Parker Synthacon is a monophonic analog synthesizer that was built between 1975 and 1979 by Steiner-Parker, a Salt Lake City-based synthesizer manufacturer. It was introduced as a competitor to other analog synthesizers, like the Minimoog and ARP Odyssey.

Arturia MiniBrute Synthesizer

The Arturia MiniBrute is a synthesizer manufactured by Arturia. Although the MiniBrute was the first piece of hardware created by Arturia—which had previously exclusively marketed software synthesizers—it generated strong sales.

Eurorack Standard that allows for the creation and modification of modular synthesizers

Eurorack is a modular synthesizer format originally specified in 1996 by Doepfer Musikelektronik. It has since grown in popularity, and as of 2018 has become a dominant hardware modular synthesizer format, with over 5000 modules available from more than 270 different manufacturers ranging from DIY kits and boutique, cottage-industry designers to well-known, established synth mass-manufacturers like Moog and Roland.

Moog Mother-32

The Mother-32 is a semi-modular analog synthesizer. Introduced in 2015, it was the first tabletop unit produced by Moog Music. It has a single voltage controlled audio oscillator, a voltage controlled low frequency oscillator, a voltage controlled filter switchable between high and low pass, an AR envelope generator with switchable sustain, a voltage controlled amplifier, and a white noise generator. It also features a 32–step monophonic sequencer, a 13-note keypad, and a 32-point patch bay including assignable outputs. The Mother-32 is manufactured in Asheville, North Carolina.


The Mother-32 is an analog semi-modular desktop synthesizer released by Moog Music Inc. in 2015.


  1. 1 2 3 4 "Eight 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. ISBN   978-0195394894.
  4. Pinch, Trevor; Trocco, Frank (2004). Analog Days: The Invention and Impact of the Moog Synthesizer. Harvard University Press. ISBN   978-0-674-01617-0.
  5. Kozinn, Allan. "Robert Moog, Creator of Music Synthesizer, Dies at 71". New York Times. Retrieved 2018-12-03.
  6. 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. "Technical Details A-100".
  9. "DIY Info".

Further reading

Mechanical specifications