A synthesizer or synthesiser (often abbreviated to synth) is an electronic musical instrument that generates audio signals that may be converted to sound. Synthesizers may imitate traditional musical instruments such as piano, flute, vocals, or natural sounds such as ocean waves; or generate novel electronic timbres. They are often played with a musical keyboard, but they can be controlled via a variety of other devices, including music sequencers, instrument controllers, fingerboards, guitar synthesizers, wind controllers, and electronic drums. Synthesizers without built-in controllers are often called sound modules, and are controlled via USB, MIDI or CV/gate using a controller device, often a MIDI keyboard or other controller.
Synthesizers use various methods to generate electronic signals (sounds). Among the most popular waveform synthesis techniques are subtractive synthesis, additive synthesis, wavetable synthesis, frequency modulation synthesis, phase distortion synthesis, physical modeling synthesis and sample-based synthesis.
Synthesizers were first used in pop music in the 1960s. In the late 1970s, synths were used in progressive rock, pop and disco. In the 1980s, the invention of the relatively inexpensive Yamaha DX7 synth made digital synthesizers widely available. 1980s pop and dance music often made heavy use of synthesizers. In the 2010s, synthesizers are used in many genres, such as pop, hip hop, metal, rock and dance. Contemporary classical music composers from the 20th and 21st century write compositions for synthesizer.
The beginnings of the synthesizer are difficult to trace, as it is difficult to draw a distinction between synthesizers and some early electric or electronic musical instruments.
One of the earliest electric musical instruments, the Musical Telegraph, was invented in 1876 by American electrical engineer Elisha Gray. He accidentally discovered the sound generation from a self-vibrating electromechanical circuit, and invented a basic single-note oscillator. This instrument used steel reeds with oscillations created by electromagnets transmitted over a telegraph line. Gray also built a simple loudspeaker device into later models, consisting of a vibrating diaphragm in a magnetic field, to make the oscillator audible. This instrument was a remote electromechanical musical instrument that used telegraphy and electric buzzers that generated fixed timbre sound. Though it lacked an arbitrary sound-synthesis function, some have erroneously called it the first synthesizer.
The Teleharmonium console (1901) and Hammond organ (1935).
In 1897 Thaddeus Cahill was granted his first patent for an electronic musical instrument, which by 1901 he had developed into the Telharmonium capable of additive synthesis. Cahill's business was unsuccessful for various reasons, but similar and more compact instruments were subsequently developed, such as electronic and tonewheel organs including the Hammond organ, which was invented in 1935.
Early electric instruments
Left: Theremin (RCA AR-1264; 1930). Middle: Ondes Martenot (7th-generation model in 1978). Right: Trautonium (Telefunken Volkstrautonium Ela T42; 1933).
In 1906, American engineer Lee de Forest invented the first amplifying vacuum tube, the Audion whose amplification of weak audio signals contributed to advances in sound recording, radio and film, and the invention of early electronic musical instruments including the theremin, the ondes martenot, and the trautonium. Most of these early instruments used heterodyne circuits to produce audio frequencies, and were limited in their synthesis capabilities. The ondes martenot and trautonium were continuously developed for several decades, finally developing qualities similar to later synthesizers.
In the 1920s, Arseny Avraamov developed various systems of graphic sonic art, and similar graphical sound and tonewheel systems were developed around the world. In 1938, USSR engineer Yevgeny Murzin designed a compositional tool called ANS, one of the earliest real-time additive synthesizers using optoelectronics. Although his idea of reconstructing a sound from its visible image was apparently simple, the instrument was not realized until 20 years later, in 1958, as Murzin was, "an engineer who worked in areas unrelated to music".
Subtractive synthesis and polyphonic synthesizer
In the 1930s and 1940s, the basic elements required for the modern analog subtractive synthesizers — electronic oscillators, audio filters, envelope controllers, and various effects units — had already appeared and were utilized in several electronic instruments.
The earliest polyphonic synthesizers were developed in Germany and the United States. The Warbo Formant Orgel developed by Harald Bode in Germany in 1937, was a four-voice key-assignment keyboard with two formant filters and a dynamic envelope controller.
The Hammond Novachord released in 1939, was an electronic keyboard that used twelve sets of top-octave oscillators with octave dividers to generate sound, with vibrato, a resonator filter bank and a dynamic envelope controller. During the three years that Hammond manufactured this model, 1,069 units were shipped, but production was discontinued at the start of World War II. Both instruments were the forerunners of the later electronic organs and polyphonic synthesizers.
Monophonic electronic keyboards
n the 1940s and 1950s, before the popularization of electronic organs and the introductions of combo organs, manufacturers developed various portable monophonic electronic instruments with small keyboards. These small instruments consisted of an electronic oscillator, vibrato effect, and passive filters. Most were designed for conventional ensembles, rather than as experimental instruments for electronic music studios, but contributed to the evolution of modern synthesizers. These instruments include the Solovox, Multimonica, Ondioline, and Clavioline.
In the late 1940s, Canadian inventor and composer, Hugh Le Caine invented the Electronic Sackbut, a voltage-controlled electronic musical instrument that provided the earliest real-time control of three aspects of sound (volume, pitch, and timbre)—corresponding to today's touch-sensitive keyboard, pitch and modulation controllers. The controllers were initially implemented as a multidimensional pressure keyboard in 1945, then changed to a group of dedicated controllers operated by left hand in 1948.
In Japan, as early as in 1935, Yamaha released Magna organ, a multi-timbral keyboard instrument based on electrically blown free reeds with pickups. It may have been similar to the electrostatic reed organs developed by Frederick Albert Hoschke in 1934 and then manufactured by Everett and Wurlitzer until 1961.
In 1949, Japanese composer Minao Shibata discussed the concept of "a musical instrument with very high performance" that can "synthesize any kind of sound waves" and is "...operated very easily," predicting that with such an instrument, "...the music scene will be changed drastically.