Moog developed a means of controlling pitch through voltage, the voltage-controlled oscillator.
: 7 Designed by American engineer Robert Moog, the synthesizer was composed of separate modules which created and shaped sounds, connected by patch cords. The authors of Analog Days define "the early years of the synthesizer" as between 1964 and the mid-1970s, beginning with the debut of the Moog synthesizer. Many of Moog's inventions, such as voltage-controlled oscillators, became standards of synthesizers. Robert Moog with a Moog modular synthesizer. It was acquired by the Columbia-Princeton Electronic Music Center and used almost exclusively by Milton Babbitt, a composer at Princeton University. The instrument read punched paper tape that controlled an analog synthesizer containing 750 vacuum tubes. In 1957, Harry Olson and Herbert Belar completed the RCA Mark II Sound Synthesizer at the RCA laboratories in Princeton, New Jersey. In 1948, the Canadian engineer Hugh Le Caine completed the electronic sackbut, a precursor to voltage-controlled synthesizers, with keyboard sensitivity allowing for vibrato, glissando, and attack control. In the late 1930s, the Hammond Organ Company built the Novachord, a large instrument powered by 72 voltage-controlled amplifiers and 146 vacuum tubes.
Although subtractive synthesis built the basis for almost all analog synthesizers during the 1970s, it did not offer the possibility to create more complex sound structures.
The FM synthesis emulates piano-, bass- or bell-like sounds with more authenticity than those based on substractive synthesis (e. The DX7 underlying FM (Frequency Modulation) synthesis with its percussive and clear sounds is significant for many songs in the 1980s.