We examined the signal paths and significant components used in Subtractive Synthesizers. We also emphasized the importance of flow-charting synthesizers to better understand how the various controls and systems interconnect. We identified three basic types of components: Generators, Processors & Controllers. Generators include circuits that create audio signals, essentially Oscillators and Noise Generators. Processors include devices that alter audio signals such as Filters, Amplifiers, Chorus and Distortion. Controllers generate signals that modify the behavior of Generators and Processors and even other controllers. These include devices such as the MIDI Keyboard (Trigger, Note Number, Velocity), Low-Frequency Oscillators, Envelope Generators, and Lag & Sample-and-Hold processors.
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Generators: Oscillator (VCO) Noise Generator Inputs: Voltage Control Signals Outputs: Audio Signal |
Processors: Amplifier (VCA) Filters (VCF) Distortion & Overdrive Reverb & Delay Effects Flanging, Chorus & Ensemble Dynamic Effects (Compression, gating, etc.) Inputs: Audio Signal Voltage Control Signals Outputs: Audio Signal |
Controllers: Envelope Generator Keyboard pitch Keyboard Trigger and Gate Signals MIDI Velocity Low Frequency Oscillator (LFO) Lag Processor Sample & Hold Generator Inputs: User Input Voltage Control Signals Output: Voltage Control Signals |