Types of Synthesis
There are two types of synthesis: subtractive synthesis and additive synthesis. Additive synthesis, is about using several sine waves in unison in order to generate basic frequencies, lacking complex overtones. Generally, to develop rhythmic timbres using additive synthesis, sine waves are set to different harmonic frequencies. This type of synthesis is more difficult to program compared to subtractive type therefore the popularity of it has decreased over time.
During 1960s, sonic sculptors and sound designers moved toward subtractive synthesis and it became an international standard and commonly accepted method of analog sound modulation. This method involves a practice of moving the waveforms which contain multitude of overtones through various filters and oscillators which in turn “subtract” various frequencies while amplifying the others - creating richly harmonic waveforms and overtones.
Below we will describe several key synthesis terminology.
Sine Wave (SW)
By itself, sine wave is a fundamental frequency with no harmonics that consists of periodic voltages that rise and fall evenly and symmetrically- following trigonometric formula for the sine function. Through oscillator modulation sine wave produces vibrato and through pitch modulation it produces tremolo.
Envelope Generator (EG)
EG is about controlling digital signal via ADSR; attack, decay, sustain and release. Every sound has a beginning, middle and end thus its’ sonic levels change over time relative to specific parameters. EG gives the musical note - controllable dynamics.
Linear Frequency Modulation (FM)
Type of synthesis in which increasing and decreasing the amount of modulation does not end up affecting the central frequency of the main oscillator, which remains stable and constant. In 1983 Yamaha released the DX7, first FM digital synthesizer capable of Linear Frequency Modulation.
At Pretty Samples, we have several teams involved in production of sample packs. One of the teams is all about synthesis of sound, creation of sonics from scratch.
Yamaha DX7, Poster Advertisement from 1983.