Additive synthesis
, The additive synthesis is a method of synthetic sound generation and is, for example, in electronic musical instruments such as synthesizers and drawbar organs used. In additive synthesis, in contrast to subtractive synthesis, the sound is not created by filtering out the undesired components from a spectrum rich in overtones , but by creating the sound by combining the desired harmonic partials.
Working principle
Additive synthesis is based on the theorem of the French mathematician Fourier (1768–1830) that every conceivable sound can be generated from a suitable mixture of many individual elementary sinusoidal oscillations ( Fourier synthesis ). In order to create a complex sound, many partials are necessary, which must be dynamically controlled by means of envelopes . If you wanted to fully influence 512 partials each with the ADSR envelope , you would get 2048 parameters, which makes operation and handling quite cumbersome. This creates an extreme hardware or computing effort. In contrast to subtractive synthesis, additive synthesis allows very precise sound characteristics due to its analytical process .
Electronic organs
A simple, early representative of this synthesis form is the drawbar organ . She has several drawbars. Each drawbar provides a sinusoidal partial tone of the overtone series , the volume of which can be adjusted by pulling out or pushing in the drawbar. The classic drawbar organ has 9 drawbars per manual.
synthesizer
The Synclavier was one of the first digital synthesizers to use additive synthesis. The K1 was the first in a line of synthesizers such as the Kawai K5 and K5000 . The sound generation of the Kawai K5000 made the first 128 partials available as sinusoidal oscillations, whereby the respective volume of the partials was retrieved from the memory. Programming sounds using this large number of partials is only possible thanks to a few built-in functions that allow partials to be grouped.
distribution
To understand additive synthesis, knowledge of acoustics or music theory in the form of the partial tone series is very helpful. Additive synthesis is more difficult to understand intuitively than z. B. subtractive synthesis . In addition to the more complex technical feasibility, this may be a reason for the rather low spread of this synthesis method.
Another synthesis method based purely on sine waves is FM synthesis .
literature
- Thomas Görne: Sound engineering. Fachbuchverlag Leipzig in Carl Hanser Verlag, Munich et al. 2006, ISBN 3-446-40198-9 .
- Roland Enders: The home recording manual. The way to optimal recordings. 3rd, revised edition, revised by Andreas Schulz. Carstensen, Munich 2003, ISBN 3-910098-25-8 .
- Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.), "Handbuch der Tonstudiotechnik", 8th, revised and expanded edition, 2 volumes, publisher: Walter de Gruyter, Berlin / Boston, 2014, ISBN 978-3- 11-028978-7 or e- ISBN 978-3-11-031650-6 .