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Software synthesizer
Synthesizer in the Technisches Museum Wien

A synthesizer ( [ˈzʏntəsa͜izɐ] ; English pronunciation [ˈsɪnθəsaɪzɚ] ) is a musical instrument that counts among the electrophones and generates tones electronically using sound synthesis . It is one of the central tools in the production of electronic music . A distinction is made between analog and digital synthesizers. As in many other areas of technology, digital devices have almost completely replaced pure analog technology. However, many older analog devices are still in use because of their characteristic properties and some have achieved cult status among musicians. The characteristic sound of certain common devices and the creative use of their peculiarities has often influenced the development of entire musical styles, for example in acid house , techno and drum and bass .


Electric organs are based on the principle of additive synthesis, in which several vibrations are mixed together. In the Hammond organ of 1935, sinusoidal vibrations were generated by shaft-driven gears which induced electrical vibrations in pickups; for each harmonic oscillation there was a wheel. In later devices the oscillations were generated by electronic circuits. The sounds produced by electronic organs were far less modulatable than those of today's synthesizers, but they had the advantage of being polyphonic .

The Novachord , also developed by the Hammond company and built in 1,069 copies between 1939 and 1942, can be considered the first true polyphonic synthesizer with an envelope generator and filters. It worked with tubes. Due to a lack of commercial success, however, production was not resumed after the end of the Second World War.

In 1950 RCA produced experimental devices for generating speech and music. In the New York test laboratory of the Radio Corporation of America , the engineers Harry Ferdinand Olson and Herbert Belar constructed a punched tape- controlled device, the Mark I RCA synthesizer. Here, tones were generated by tuning fork oscillators; the sinusoidal oscillations were picked up electromagnetically and converted into sawtooth oscillations rich in overtones. Above all, the composer Milton Babbitt dealt with this device and was also a consultant for the successor model Mark II, which was manufactured in the Columbia-Princeton Electronic Music Center .

The Mark II Music Synthesizer (1958) could only play a piece after it had been completely programmed and had to be reprogrammed for the next. It was controlled via punched tape . In 1958, at the BBC Radiophonic Workshop , Daphne Oram developed a new type of synthesizer that used the so-called "Oramics" technique. The synthesizer was controlled via 35 mm film. It was used on the BBC for a number of years .

Hugh Le Caine , John Hanert , Raymond Scott , Percy Grainger (with Burnett Cross ), and others built a variety of electronic musical instruments in the late 1940s and 1950s.

From the 1960s onwards, the development of electronics had advanced to such an extent that sounds and tones could be generated in real time , but these devices were limited to studio use due to their size. These devices were mostly of a modular design, and the individual components could be wired together manually. Many of these first devices were experimental one-offs. Donald Buchla , Hugh Le Caine, Raymond Scott and Paul Ketoff were the pioneers in the 1960s, with only Buchla offering a commercial device.

Analog synthesizers


Analog modular synthesizers from Moog and ARP (rear)

Robert Moog presented the first playable and configurable synthesizer in 1964 at the " Audio Engineering Society convention". Already during the development he was able to inspire the musician Walter Carlos (later Wendy Carlos) for the modular synthesizer . The new sound, as on the "best-selling classical music album" Switched-On Bach by Walter Carlos in 1968, was considered sensational.

At almost the same time, Don Buchla developed his first synthesizer.

In the late 1960s, a multitude of recordings were made using the new Moog synthesizer sound. The piece of popcorn that became a global hit and was the first to be created entirely with the Moog synthesizer became famous. The Beatles also discreetly used a Moog on their album Abbey Road , for example to give the final chorus of Here Comes the Sun an airy, “smart” sound.

At the same time, Moog set the standards that allowed the linking of different synthesizers, such as B. an interface for external control via a logarithmic 1- volt / octave pitch control. The synthesizer was normally controlled via a normal keyboard or a sequencer , in which pitch sequences could be programmed in time and which controlled the synthesizer via the interface mentioned.

However, since the Moog Modular System was too big for stage and live use and too cumbersome to operate, Moog integrated the most important components of its synthesizer into a compact housing, which was named Minimoog and came onto the market in 1970. The Minimoog was a method used by many musicians and widely used musical instrument in the following years. During the 1970s, various other companies came onto the market with synthesizers, including a. ARP Instruments (by Alan Robert Pearlman ), Oberheim (by Tom Oberheim ) and Sequential Circuits . However, all synthesizers had two major disadvantages: On the one hand, they could only be played monophonically , and on the other hand, they could not be programmed permanently, so you could not save any settings.

Nevertheless, groups and musicians such as Pink Floyd , Human League , Emerson, Lake and Palmer , Kraftwerk , Jean Michel Jarre , Tangerine Dream , Ed Starink , Klaus Schulze , Larry Fast and Vangelis specialized in synthesizers. The rock band The Who used a sequencer-controlled synthesizer in their song Won't Get Fooled Again (1971).


Yamaha GX-1

Most early synthesizers were monophonic. Few were able to produce two tones at the same time, like the Moog Sonic Six , the ARP Odyssey, and the EML 101 . At that time, real polyphony could only be achieved using the principle of the electric organ (octave divider principle). The ARP Omni , the Moog Polymoog and the Opus 3 therefore combined both elements. It was not until the mid-1970s that the first real polyphonic synthesizers came onto the market with the Yamaha GX-1 , the Yamaha CS-80 and the Oberheim Four-Voice . The GX-1 is therefore considered to be the first polyphonic synthesizer. But these were complex, heavy and expensive. The first affordable polyphonic and also microprocessor-controlled and thus programmable synthesizer was the Prophet-5 from Sequential Circuits in 1978 . For the first time musicians were able to save their settings and call them up again at the push of a button. In addition, it was - compared to the modular systems - compact and light. The GDR followed suit only in 1987 with the Tiracon 6V .

Analog sound generation

Analog synthesizers of the 1970s are often built as a modular system. The individual components ( signal generators , filters , modulators ) are mounted in a rack and are connected to one another using a jack plug cable (or a patch panel) as required .

A tone is usually composed of a basic tone , which determines the pitch , and overtones - also called partials or harmonic tones - which determine the timbre . Different types of sounds are created by the different structure of the overtone series. The individual overtones differ in frequency , amplitude and in time of build- up and breakdown. The sound generation in the analog synthesizer was based on a few basic waveforms based on mechanical instruments: the tilting wave (similar to a string) , the square wave (similar to a woodwind) and the triangular wave (similar to a flute). See: Signal generator

Voltage Controlled Oscillator (VCO)

The VCO is a voltage-controlled oscillator and is the most important component in analog synthesizers. The frequency and thus the pitch can be changed via a control voltage . Using several oscillators at the same time increases the number of tonal design options. Often the oscillators are slightly detuned from each other, which makes the sound impression fuller ( unison or beat , similar to a chorus effect ). DCOs ( Digitally Controlled Oscillators ) are used in digital synthesizers . In contrast to the VCO, the frequency is not determined by an electrical voltage, but by a numerical value that is specified by a microprocessor .

Noise Generator (NG)

The noise generator generates noise signals of different spectral characteristics. In analogy to the spectral energy distribution in white light, one speaks of white noise when all frequencies occur in equal proportions. If the frequency distribution deviates from the uniform distribution, i. H. If certain frequency ranges dominate, it is colored noise. Some synthesizers have the ability to generate 1 / f noise (pink noise) in which the low frequencies predominate. In addition to being used as an audio signal , noise can also serve as a modulation source. This creates unusual and interesting sounds.

Voltage Controlled Filter (VCF)

The actual sound shaping takes place in the voltage-controlled filter (VCF). The most common filter is the low-pass filter, which allows low frequencies to pass and attenuates high frequencies. The high-pass filter works in exactly the opposite way. The series connection of low and high pass filters creates a band pass ; a bandstop filter results from parallel connection . A special frequency band is attenuated here, while the other frequency components pass unhindered. The slope of the filter determines how smoothly or abruptly the transition between the pass band and stop band occurs. For synthesizers, values ​​of 12 dB (soft) and 24 dB (hard) are common.

Voltage Controlled Amplifier (VCA)

The voltage-controlled amplifier influences the volume curve or the dynamics of the sound. There are VCAs with a linear or exponential dependence on the voltage. As a synthesizer module, the VCA is mainly controlled by the envelope generator. With almost all manufacturers, however, the VCA does not work as a real amplifier, but only as an attenuator and is therefore also known as a Voltage Controlled Attenuator. Only in Moog modular systems do you find both - amplifier and attenuator modules.

The envelope generator

Envelope generators produce programmable voltage sequences that are used via the VCA to control the dynamics of a sound, or via a VCF to dynamically change the timbre. Envelope generators are often designed as ADSR generators, which have four different parameters: attack time, decay time , sustained level ( sustain level) and release time. The name ADSR is derived from the initial letters of the parameter names forth ( A ttack, D ecay, S ustain, R elease). The envelope generator is usually started by a trigger signal that is triggered by pressing a key.

The modulation

The LFO ( Low Frequency Oscillator ) synthesizer module consists of a controllable oscillator with a rather low frequency compared to the VCO. It is used to automatically carry out a periodic change in sound parameters. If the LFO controls e.g. B. the frequency of a VCO, vibrato effects or siren-like sounds are created. Modulation of the VCA with sinusoidal or triangular LFO signals results in a tremolo . A square wave signal of the LFO, however, leads to a constant repetition of the tone (mandolin effect). If the VCF is modulated with the different waveforms of the LFO, different effect variants such as wah-wah or phaser can be created when two filters are coupled to form a band pass or block .

Sample and hold

From a noise signal is a periodically sample (sample Engl.) Were removed and retained as a voltage level. If you control a VCO with this signal, the pitch changes randomly. When a VCF is controlled, the tones are randomly distributed lighter and darker (spectral modulation), which can create a “bubbling” or vaguely speech-like impression.

Frequency follower

In this module, the pitch of a signal is converted into a corresponding control voltage. It works exactly on the opposite principle of a VCO. The difficulty here is in minimizing the time it takes to identify the pitch. Since several wavelengths of a frequency are necessary to identify it, the detection time for low frequencies is longer than for higher tones.

Envelope Follower

This assembly converts the volume curve or a frequency into a corresponding voltage curve.

Ring modulator

A ring modulator multiplies two signals together. The resulting signal consists of the sum and difference frequencies of the harmonics of both input signals. If the frequencies of the two signals form simple relationships, harmonic sounds are usually obtained. However, if you choose other frequency ratios, metallic or bell-like sounds, for example, are created that can be used well for creating rhythmic or percussive sounds. The flexibility in the immediate electronic transformation of any sound results has made ring modulation a preferred method of live electronics . With modern synthesizers, which carry out the ring modulation in a purely mathematical way, you can also set the modulation depth course and thus change the timbre during the tone course.

Resonance filter

This module is used for the electronic simulation of formants . In the filter stage of synthesizers (the main filter is usually the VCF), filters that are capable of resonance are also spoken of if the filter can be parametrically driven into resonance ("ringing"): The overshoot behavior of filters at or just before the peak frequency is usually used.

If this overshoot is sufficiently amplified by feedback within the filter stage, the filter can even be set into natural oscillation (without any input signal from the VCO). The set filter frequency then determines the pitch ("whistling") of the natural oscillation. The resonance becomes audible as soon as the ADSR envelope opens the VCA via the keyboard. Both without and in combination with the actual tone generation stage (VCO or noise generator), a self-resonant filter significantly expands the scope of the tonal possibilities of a synthesizer.

Analog sequencers

Analog sequencers produce automatic control voltage sequences and trigger signals that can be used to control any voltage controlled synthesizer module. Analog synthesizers can also be controlled by digital sequencers. Today digital sequencers are again controlled by microprocessors. A distinction is made between hardware and software sequencers.

Digital synthesizers

Frequency modulation

A real revolution was the advent of synthesizers with digital sound generation, initially using FM synthesis . In principle, this is also possible with analog oscillators, in that one oscillator is modulated by a second oscillator with a frequency in the audible range, but it was not until the 1970s that the digital form was developed, which enabled a very convenient application of FM synthesis. In short, in FM synthesis, digital oscillators (so-called operators) generate various sinusoidal oscillations that modulate each other depending on a selected algorithm, so that complex waveforms can result. A unique selling point of FM synthesis in contrast to subtractive synthesis, which was common at the time, was the ability to generate percussive sounds that were particularly rich in overtones.

The FM synthesis patent has been licensed from the Japanese musical instrument manufacturer Yamaha . The first synthesizers, the GS-1 and GS-2 , were heavy and expensive devices and did not find widespread use. In 1983, the DX7 was the synthesizer that revolutionized the entire market and replaced the analog synthesizer. It was the size and weight of the Prophet-5 and was comparatively inexpensive. It was "the" synthesizer of the 1980s, and you can hardly find a pop music recording from this period that does not feature a DX7. After the expiry of the patent protection, FM synthesis found widespread use, e.g. B. in simple 4-operator synthesizers on PC sound cards.

Sound sampling

A second revolution, announced in 1979 with the first Fairlight CMI , was sampling . When sampling, natural sounds are digitized . These digital waveforms then form the basis of the sound generation. With the sampler , something was possible that was previously only available to the analog Mellotron that worked with magnetic tapes : the real reproduction of acoustic instruments.

The first systems, such as the Fairlight CMI, the E-mu emulator or later the Synclavier from New England Digital , were extremely expensive devices that were only reserved for the “big ones” in the industry. In addition, the technical possibilities of playback were initially limited due to the low resolution and storage capacity. Peter Gabriel and Kate Bush released the first recordings in 1982 on which "sampled" sounds can be heard. In 1985, the Mirage from Ensoniq, the first affordable sampler for the masses, came onto the market. Sampling soon shaped the sound of pop music in the 1980s. Today, with a computer and sound card, extensive sampling libraries can be loaded and used for computer-based music arrangements.


In 1987 Roland brought a synthesizer onto the market with the D-50 , which became very popular due to its sound generation with LA synthesis (simulation of acoustic instrument sounds using a combination of attack samples and basic waveforms, with an integrated effects device). In 1988 KORG continued the integration with the M1 . The M1 represented a new type of synthesizer, the " workstation ". For the first time, a synthesizer, effects device , drum computer and sequencer were integrated in one device. This allowed the creation of complete music sequences in one device without external hardware. After the Yamaha DX7, the Korg M1 is the best-selling synthesizer to date.

Synthesizer workstations are now also available as pure software (e.g. Synthesizer Workstation Pro ) that no longer require any hardware other than a PC. They are played via arpeggiators or MIDI files. Optionally, a keyboard can also be connected.

Physical modeling synthesizer

In the early 1990s, the first synthesizers with a new type of synthesis method, physical modeling , came onto the market.

The tonal result of an instrument is not imitated here, but a physical model (for example a vibrating string) is digitally represented, i.e. H. the model with all its properties, dimensions, elasticity, tension, etc. "exists" in a computer and kinetic energy is supplied to it at any point using a virtual exciter (e.g. a pick). The focus is initially on the physical simulation, the sound is only one way of conveying this (this way you could convey the body of the string visually). Nonetheless, PM synthesis leads to the most realistic sound results anywhere where it is necessary to imitate natural instruments, and the more detailed the physical model, the more likely it is.

The principle, which had long been known, could only be implemented in practice with the development of the Karplus-Strong algorithm and its refinement, as well as the generalization of the algorithm into a digital waveguide synthesis by Julius O. Smith III et al. For real-time calculation, powerful digital signal processors (DSP: Digital Signal Processor ) were required, as they were only available at the end of the 1980s.

As with FM synthesis, Yamaha secured the rights and developed this synthesis method together with Stanford University from 1989 ; the first synthesizer to work in this way in series production was the Yamaha VL-1 in 1994. In this way, attempts were soon made to digitally resurrect the old analog synthesizers with their sonic inadequacies as virtual analog synthesizers . These include the Clavia Nord Lead , the Access Virus and Waldorf's synthesizers . After the digital synthesizer sounds of the 1980s, there was a renaissance of analog synthesizers and their sounds in the 1990s, especially due to the emergence of techno music. Previously almost worthless synthesizers such as Roland's TB-303 increased significantly in value again.

Hybrid synthesizer

Today's synthesizers are predominantly digital and use special DSP modules for sound generation, with different forms of sound synthesis sometimes being used in parallel. Analog circuit parts are still used for input and output circuits, as well as for some of the setting controls (potentiometers).

However, some so-called hybrid synthesizers have also been developed that combine DSPs with analog components, whereby a largely digital signal path, such as e.g. B. the Waldorf Q + (analog filter, otherwise DSP-based) as well as a predominantly analog signal path (DSI Evolver, Alesis A6 Andromeda) occur. The concept of hybrid synthesizers originally dates back to the 1980s: models such as the ESQ1 from Ensoniq combined short samples or additively generated waveforms with analog filters.

A comparable concept can be found in the Sequential Circuits Prophet VS and the Waldorf Wave, Microwave I. Both synthesizers are currently popular sound generators because of their special sound aesthetics. Digital wave snippets are organized in wavetables (microwave), output via the oscillators and passed on to the other synthesis components. These synths are significantly more versatile than purely analog devices, but are equipped with comparable modulation sources and destinations and they benefit from the analog amplifier and filter modules that are perceived as musical; The keywords here are mostly attributes such as warm and powerful. The Waldorf Q + uses a virtual analog sound generation, but outputs this via analog filters. Because of its spartan user interface, which is in clear contrast to the multitude of changeable parameters, a DIY controller from Stereoping is currently available as a MIDI controller for editing the sounds for the Microwave I.

Although the Waldorf Blofeld is primarily advertised as a "virtual analog (wavetable) synthesizer", it can be seen as a "hybrid" because of its 60 MB sampling option. This is all the more true as the samples to be fed in using the tool (Specter) interact with the other waveforms and synthesis functions of the Blofeld.

The Tempest Drum Machine, which was developed under the DSI label by the synth pioneers Dave Smith and Roger Linn , is also a hybrid synthesizer in groove box format. The sound generation includes 6 analog voices with 2 analog and 2 digital oscillators each, input is made via illuminated pads, a sequencer reproduces the compositions, the sounds can, among other things, be played back. a. can be changed in real time using FX sliders and controls. Conceptually, the DSI-Instrumente-Evolver and the Prophet 12 and its little brother Pro2 also belong to this line.

The SY99 from Yamaha, on the other hand, was able to feed loaded samples into FM synthesis (see above) and process the resulting waveforms again subtractively (filter), thus combining samplers and digital FM synthesis with subtractive sound generation.

Software synthesizer

So-called “native software synthesizers” are a new trend. Due to the high performance of modern PCs , it is possible to generate digital sound on unspecialized processors . There are now different software synthesizers for each type of synthesis , some of which are simulations of well-known hardware synthesizers. Well-known old instruments such as Fender Rhodes pianos or the Hammond B3 organ are also simulated.

This software synthesizers are often a master keyboard , a pad - controller or dial controlled. Most of these synthesizers work as VST (Virtual Studio Technology) plugins, which can be easily integrated into most DAW (Digital Audio Workstation) programs.

Digital sound generation

Cell phone synthesizer

Korg iMono / Poly on the iPhone.

Today's mobile phones have so much computing power that they can play synthesizer apps as application programs, which in terms of their sound design options come ever closer to classic analog and many digital synthesizers. They have several oscillators with numerous waveforms that can be pulse-width modulated, frequency and amplitude modulation, detuning, envelope generators, delay, exciter, chorus and reverb effects as well as dynamic filters. They are preferably played via MIDI files, as playing on a small mobile phone keyboard is a bit tedious. One example of this is the Windows Phone Synthesizer (see web links).

Sound synthesis and effects filters

Technical related systems


Technically related to the synthesizer, the vocoder is used to modulate the sound of analog instrumental sounds or noises (carrier signal), mostly with the help of the human voice as a control signal. The dynamic and timbre properties of the controlling speech signal are transferred to the instrumental sound with the help of filters and control voltages, so that it appears to "speak" or "sing".

Filter bank

A filter bank is an analog or digital system that does not have its own sound generation, but can process signals fed in. In classic analog systems these usually consist of RC filters, in digital systems of FIR filters . In modern systems, the signals are also broken down using FFT , processed in the frequency domain and then resynthesized.


A small revolution in the development of synthesizers was the development of MIDI , a simple standard digital serial interface for synthesizers. It was developed by Roland and Sequential Circuits and introduced in 1983. It has established itself as the standard industrial interface in a very short time. To this day, it can be found in almost unchanged form in every synthesizer and allows a wide variety of electronic devices to be connected to one another in a simple manner. In 1991, General MIDI (GM) expanded the standard to include sound mapping. So z. B. to always find an oboe sound in the same program slot. This makes it possible to play complete pieces of music with the correct sound allocation via GM-compliant playback devices.

Sound module

A sound module is a sound generating device or software module without a keyboard ; it is connected to the appropriate devices via MIDI or USB .


A sequencer controls a certain sequence (sequence) of tones or sound events that are generated by another device or module. Sequencers spread along with MIDI, which mostly serves as the standard for transmitting data. The arpeggiator offers a similar function, which saves a shorter, coherent sequence of notes, which can then be played by pressing a button.

Precision oscillator

In electrical engineering , a synthesizer describes an electronic device for generating monophonic, ultra-pure vibrations, such as sawtooth , sine , triangular and square waves or needle pulse trains . Corresponding devices, also known as function generators , are used to check electronic circuits, often amplifiers or filters. As these are laboratory devices, they have an extremely low noise level and a distortion factor that is at the limit of measurability .

Such generators, which today are almost exclusively implemented with digital components, are also known as digital oscillators. Typical methods are the DDS

Synthesizer manufacturer

The following is a list of well-known manufacturers who significantly shaped the development of synthesizers. Areas over which the respective manufacturer has influenced are given in brackets.


  • Bernd Enders : The sound world of the music synthesizer. The introduction to how a module synthesizer works . Franzis-Verlag, Munich 1985, ISBN 3-7723-7761-0 .
  • Peter Forrest: The AZ of analogue synthesisers . 2 volumes. Susurreal Publishing, Crediton 1998, ISBN 0-9524377-2-4 (detailed description of all analog synthesizers and organs ever produced up to 1998; English).
  • Peter Gorges: Synthesizer Programming . 3rd unchanged edition. Wizoo, Bremen 2004, ISBN 3-934903-47-9 (several editions).
  • Uwe G. Hoenig: Workshop Synthesizer. Sound generation for musicians. Understand and play from analog to digital to software synthesizers . 3. Edition. PPV Medien, Bergkirchen 2006, ISBN 3-932275-27-6 .
  • Moogulator, Gavin Lucas: Hands On Synthsound. DVD learning course . Schwabach 2010, ISBN 978-3-9811987-8-2 ( ).
  • Wolfgang Röllin, Bernardo Egli: The great synth book. Sounds, tricks, music, tips . Voggenreiter, Bonn-Bad Godesberg 1984, ISBN 3-8024-0134-4 .
  • André Ruschkowski: Soundscapes. Electronic sound generation and music . Lied der Zeit, Berlin 1990, ISBN 3-7332-0058-6 .
  • Holger Steinbrink: Synthesizer Programming - Sound Design Tips & Tricks . audio workshop specialist script, Waldorf 2005 ( ).
  • Allen Strange: Electronic music. Systems, techniques and controls . Wm. C. Brown, Dubuque IA 1972.
  • Synthesizer Workstation Pro. The music laboratory for your PC. Franzis, Poing near Munich 2010, ISBN 978-3-645-70094-8 .

Web links

Wiktionary: Synthesizer  - explanations of meanings, word origins, synonyms, translations
Commons : Synthesizer  - collection of images, videos and audio files

Individual evidence

  1. Synthesizer .
  2. from Joker Nies: The Buchla-Sound: A special kind of synthesizer. Keyboards, March 14, 2017, accessed on August 3, 2020 .
  3. ^ The MOST Yamaha goes to Mickie. In: YAMAHA: GX-1. HOPPWEI - Who Advertises How Sounds Was, January 1978, accessed August 2020 .
  4. Nikolai Kaeßmann: The 10 best synthesizers of all time :: Bondedo, August 16, 2017, accessed August 3, 2020 .