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All analogue synthesizers have three main parts :
1. Voltage controlled oscillators (VCO)s : control pitch & wave shape.
2. Voltage controlled amplifiers (VCA)s : control volume.
3. Voltage controlled filters (VCF)s : control frequency response.
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These parts are commonly controlled three ways :
1. Modulation by LFOs.
2. Envelope followers : The louder you play the instrument, the more the sound changes.
3. Envelope generators : Controls for attack, decay, sustain, and release. (These are not commonly used in non-synthesizer sound effects.)
| Control | VCO | VCA | VCF |
| LFO Modulation | Vibrato* | Tremolo | Auto Wah |
| Envelope follower | – | – | Auto Wah |
| Envelope generator | Synth. | Synth. | Synth. |
Figure 1 : Examples of common audio effects using analogue synthesizer components.
*Vibrato created using VCOs is different than the vibrato created by delay effects like chorus and flangers. It is also different than the Cool Edit 2000 pitch shifter option. That is done by resampling the sound file. The computer mathematically recalculates sound volume and frequency information.
VCOs can create vibrato and pitch shifter effects like lower octaves, higher octaves, and chord tones. Each VCO creates one note at a time. You need three separate VCOs to create a chord.