A system for generating waveforms or sounds by combining basic waveforms or sampled sounds prior to further processing with filters and envelope shapers. Some content below with thanks to Wikipedia. Additive Synthesis Additive synthesis is a technique of audio synthesis which creates musical timbre. The timbre of an instrument is composed of multiple harmonic or non-harmonic partials (individual sine waves), of different frequencies and amplitudes, that change over time. Additive synthesis allows the emulation of sounds by giving control over the frequency and amplitude of each individual harmonic or partial. Often, each harmonic generator has its own customizable volume envelope, creating a realistic, dynamic sound that changes over time. Certain organ pipes, which create sinusoidal waves (mostly flute pipes), can be combined in the manner of additive synthesis. However, pipes which generate other types of wave forms (for example square wave generating clarinet stops) are not suited to this purpose. More contemporary popular implementations of additive synthesis include the Kawai K5000 series of synthesizers in the 1990s and, more recently, software synthesizers such as the Camel Audio Alchemy, Image-Line Morphine, the VirSyn Cube, White Noise Audio Soft WNAdditive, and the ConcreteFX softsynth Adder. Another instrument with this capability is the Hammond organ, which uses nine drawbars to control the harmonics. The Hammond was invented in 1935 as a substitute for the much bulkier and expensive pipe organ.