User:Phazer1980

=Practical Guide To Subtractive Synthesis.=

Introduction
Already you maybe wonder what ”subrative synthesis” means, well it means that you start out with sound material rich in harmonics (overtones) and the filter some of there harmoics out (subtract them). From know on the word ”subtractive” is implicit before the wor dsynth



Oscillators
A very simple example is a one oscillator synthesizer; the oscillator producers a sawtooth wave rich in overtones, this signal is then routed to the synthesizer's low pass filter that in a “naturally” sounding way filters out some of the overtones of the original signal making it ”duller”. But if this was it, synthesizers could only generate static sounds of varying harmonic content.



Envelope generators
Luckily all modern synthesizers have at least one so-called envelope generator; an envelope generator is an automated ”modifier” (modulator) that changes sound shaping parameters over time and each cycle starts when you press a key on the keyboard. Most envelope generators are of the type ”attack, decay, sustain release”. If an envelope generator controls the amplifier stage then ”attack” is the time it takes from a key is pressed until volume has reach maximum. ”Decay” is is the time it takes for the volume to drop to the level (%) set by the ”sustain” parameter; if you keep holding the key down after the ”attack” and ”decay” phases have passed, the volume will remain at the level set by ”sustain”. ”Realease” is the time it takes for volume to drop to zero after they has been lifted.

Envelope generators are most often used to control the filter and the amplifier and this is logical as they way harmonic content and volume develop over time for most instruments can be roughly emulated by the the described type of envelope generators.

This very simple arrangement is not entirely theoretical; the famous Roland TB-303 basically works in this way: Single oscillator->filter+envelope->amplifier envelope.



LFOs:
LFO stands for Low Frequency Oscillator and is another modulator. The LFO is set at the chosen rate and modulates parameters in the synthesizer. If it modulates the filter the filter periodically opens and closes.

