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Subtractive synthesis is a method of
sound synthesis A synthesizer (also synthesiser or synth) is an electronic musical instrument that generates audio signals. Synthesizers typically create sounds by generating waveforms through methods including subtractive synthesis, additive synthesis an ...
in which
overtones An overtone is any resonant frequency above the fundamental frequency of a sound. (An overtone may or may not be a harmonic) In other words, overtones are all pitches higher than the lowest pitch within an individual sound; the fundamental i ...
of an audio signal are attenuated by a filter to alter the
timbre In music, timbre (), also known as tone color or tone quality (from psychoacoustics), is the perceived sound of a musical note, sound or tone. Timbre distinguishes sounds according to their source, such as choir voices and musical instrument ...
of the sound.


Overview

Subtractive synthesis relies on source sounds that have overtones, such as non-sinusoidal waveforms like
square In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...
and triangle waves, or
white White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wa ...
and
pink noise Pink noise, noise, fractional noise or fractal noise is a signal (information theory), signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequenc ...
. These overtones are then
modulated Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message ...
to alter the source sound. This modulation can happen in a wide variety of ways, such as voltage-controlled or low-pass filters. The technology developed in experimental electronic studios which were primarily focused on
telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...
and military applications. Early examples include
Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...
'
Voder 400px, Schematic circuit of the VODER The Bell Telephone Laboratory's Voder (abbreviation of Voice Operating Demonstrator) was the first attempt to electronically synthesize human speech by breaking it down into its acoustic components. It was ...
(1937–8). Composers began applying the concept of subtractive synthesis beyond the recording studio in concert music.
Henri Pousseur Henri Léon Marie-Thérèse Pousseur (; 23 June 1929 – 6 March 2009) was a Belgian classical composer, teacher, and music theorist. Biography Pousseur was born in Malmedy and studied at the Academies of Music in Liège and in Brussels from 19 ...
's '' Scambi'' (1957) subjects white noise to filters and uses the resulting sounds to create montages. '' Mikrophonie I'' (1964) by
Karlheinz Stockhausen Karlheinz Stockhausen (; 22 August 1928 – 5 December 2007) was a German composer, widely acknowledged by critics as one of the most important but also controversial composers of the 20th and early 21st centuries. He is known for his groun ...
uses a tam-tam and a microphone as the primary sound source which is then filtered extensively by two sound projectionists. Until the advent of
digital synthesizer A digital synthesizer is a synthesizer that uses digital signal processing (DSP) techniques to make musical sounds, in contrast to older analog synthesizers, which produce music using analog electronics, and samplers, which play back digital rec ...
s, subtractive synthesis was the nearly universal electronic method of sound production. Its popularity was due largely to its relative simplicity. Subtractive synthesis was so prevalent in
analog synthesizers An analog synthesizer () is a synthesizer that uses analog circuits and analog signals to generate sound electronically. The earliest analog synthesizers in the 1920s and 1930s, such as the Trautonium, were built with a variety of vacuum-tub ...
that it is sometimes called "analog synthesis". It was the method of sound production in instruments like the
Trautonium The Trautonium is an electronic synthesizer invented in 1930 by Friedrich Trautwein in Berlin at the Musikhochschule's music and radio lab, the Rundfunkversuchstelle. Soon afterward Oskar Sala joined him, continuing development until Sala's de ...
(1930),
Novachord The Novachord is the world's first commercial polyphonic synthesizer, polyphonic synthesizer. Incorporating many circuit and control elements found in modern synthesizers, and using subtractive synthesis to generate tones, it was designed by Joh ...
(1939), Buchla 100 (1960s),
EMS VCS 3 The VCS 3 (or VCS3; an initialism for ''Voltage Controlled Studio, version #3'') is a portable analogue synthesizer with a flexible modular voice architecture introduced by Electronic Music Studios (EMS) in 1969. EMS released the product ...
(1969),
Minimoog The Minimoog is an analog synthesizer first manufactured by Moog Music between 1970 and 1981. Designed as a more affordable, portable version of the modular Moog synthesizer, it was the first synthesizer sold in retail stores. It was first popul ...
(1970),
ARP 2600 The ARP 2600 is a subtractive synthesizer first produced by ARP Instruments in 1971. History Developed by a design team headed by ARP namesake Alan R. Pearlman and engineer Dennis Colin, the ARP 2600 was introduced in 1971 as the successor to ...
(1971),
Oberheim OB-1 The Oberheim OB-1 was a Monophonic synthesizer, monophonic analog synthesizer introduced by Oberheim Electronics in late 1977. With the ability to store and recall up to 8 instances of its sound settings, it was the first completely programmable sy ...
(1978), and
Korg MS-20 The Korg MS-20 is a patchable semi-modular monophonic analog synthesizer which Korg released in 1978 and which was in production until 1983. It was part of Korg's MS series of instruments, which also included the single oscillator MS-10, the ke ...
(1978).Réveillac, Jean-Michel. ''Synthesizers and Subtractive Synthesis 1''.
John Wiley & Sons John Wiley & Sons, Inc., commonly known as Wiley (), is an American Multinational corporation, multinational Publishing, publishing company that focuses on academic publishing and instructional materials. The company was founded in 1807 and pr ...
, 2024.
Programmable sound generator A programmable sound generator (PSG) is a sound chip that generates (or synthesizes) audio wave signals built from one or more basic waveforms, and often some kind of noise. PSGs use a relatively simple method of creating sound compared to other m ...
s (PSG) relied heavily on subtractive synthesis. PSGs were used in many personal computers, arcade games, and home consoles such as the
Commodore 64 The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in ...
,
Atari ST Atari ST is a line of personal computers from Atari Corporation and the successor to the company's Atari 8-bit computers, 8-bit computers. The initial model, the Atari 520ST, had limited release in April–June 1985, and was widely available i ...
,
Mattel Mattel, Inc. ( ) is an American multinational corporation, multinational toy manufacturing and entertainment company headquartered in El Segundo, California. Founded in Los Angeles by Harold Matson and the husband-and-wife duo of Ruth Handler, ...
's
Intellivision The Intellivision (a portmanteau of intelligent television) is a home video game console released by Mattel Electronics in 1979. It distinguished itself from competitors with more realistic sports and strategic games. By 1981, Mattel Electronic ...
,
Sega is a Japanese video game company and subsidiary of Sega Sammy Holdings headquartered in Tokyo. It produces several List of best-selling video game franchises, multi-million-selling game franchises for arcade game, arcades and video game cons ...
's
Master System The is an 8-bit Third generation of video game consoles, third-generation home video game console manufactured and developed by Sega. It was originally a remodeled export version of the Sega Mark III, the third iteration of the SG-1000 series ...
, and the
ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...
.


Nomenclature

Subtractive synthesis has become a catchall for a method where source sounds are modulated, and it is sometimes applied inappropriately.Stefanakis, Nikolaos, et al. “Sound Synthesis Based on Ordinary Differential Equations.” ''Computer Music Journal'', vol. 39, no. 3, 2015. 48.


Method

The following is an example of subtractive synthesis as it might occur in an electronic instrument to emulate the sound of a plucked string. It was created with a
personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...
program designed to emulate an analogue subtractive synthesizer.


Source Sound

First, an
electronic oscillator An electronic oscillator is an electronic circuit that produces a periodic, oscillating or alternating current (AC) signal, usually a sine wave, square wave or a triangle wave, powered by a direct current (DC) source. Oscillators are found ...
produces a relatively complex
waveform In electronics, acoustics, and related fields, the waveform of a signal is the shape of its Graph of a function, graph as a function of time, independent of its time and Magnitude (mathematics), magnitude Scale (ratio), scales and of any dis ...
with audible
overtones An overtone is any resonant frequency above the fundamental frequency of a sound. (An overtone may or may not be a harmonic) In other words, overtones are all pitches higher than the lowest pitch within an individual sound; the fundamental i ...
. Only one oscillator is necessary, and the number can vary widely. In this case, two oscillators are used:
Pulse-width modulation Pulse-width modulation (PWM), also known as pulse-duration modulation (PDM) or pulse-length modulation (PLM), is any method of representing a signal as a rectangular wave with a varying duty cycle (and for some methods also a varying peri ...
is applied to both waveforms to create a more complex tone with
vibrato Vibrato (Italian language, Italian, from past participle of "wikt:vibrare, vibrare", to vibrate) is a musical effect consisting of a regular, pulsating change of pitch (music), pitch. It is used to add expression to vocal and instrumental music. ...
: The pulse-width modulated sounds are now combined at equal volume. Combining them at different volumes would create different timbres. The result is a 2-second source sound, which is ready for subtractive synthesis.


Subtractive Synthesis

The combined wave is passed through a
voltage-controlled amplifier A variable-gain (VGA) or voltage-controlled amplifier (VCA) is an electronic amplifier that varies its gain depending on a control voltage (often abbreviated CV). VCAs have many applications, including audio level compression, synthesizers and ...
connected to an
envelope generator In sound and music, an envelope describes how a sound changes over time. For example, a piano key, when struck and held, creates a near-immediate initial sound which gradually decreases in volume to zero. An envelope may relate to elements such ...
. The parameters of the sound's envelope (attack, decay, sustain and release) are manipulated to change its sound. In this case, the decay is vastly increased, sustain is reduced, and the release shortened. The resulting sound is audible for half as long as the source sound: With its new envelope, the sound is run through a
low-pass filter A low-pass filter is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filt ...
, which reduces the volume of higher overtones: To better emulate the sound of a plucked string, the filter's
cutoff frequency In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced ( attenuated or reflected) rather than ...
is lowered.


See also

* * * * * * * *


References


External links


AMS
– A free software synthesis program for ALSA. {{Sound synthesis types Sound synthesis types ru:Субтрактивный синтез