Synthesizer - Components

Components

Synthesizers generate sound through various analogue and digital techniques. Early synthesizers were analog hardware based but many modern synthesizers use a combination of DSP software and hardware or else are purely software-based (see softsynth). Digital synthesizers often emulate classic analog designs. Sound is controllable by the operator by means of circuits or virtual stages that may include:

• Electronic oscillators – create raw sounds with a timbre that depends upon the waveform generated. Voltage-controlled oscillators (VCOs) and digital oscillators may be used. Harmonic Additive synthesis models sounds directly from pure sine waves, somewhat in the manner of an organ, while Frequency modulation and Phase distortion synthesis use one oscillator to modulate another. Subtractive synthesis depends upon filtering a harmonically rich oscillator waveform. Sample-based and Granular synthesis use one or more digitally recorded sounds in place of an oscillator.
• Voltage-controlled filter (VCF) – "shape" the sound generated by the oscillators in the frequency domain, often under the control of an envelope or LFO. These are essential to subtractive synthesis.
• Voltage-controlled amplifier (VCA) – After the signal generated by one (or a mix of more Voltage-controlled oscillators), modified by filters and LFOs, and the signal's waveform is shaped (contoured) by an ADSR Envelope Generator, it then passes on to one or more voltage-controlled amplifiers (VCA) where. The VCA is a preamp that boosts (amplifies) the electronic signal before passing on to an external or built-in power amplifier, as well as a means to control its volume using an attenuator that affects a control voltage (coming from the keyboard or other trigger source), which affects the gain of the VCA.
• ADSR envelopes - provide envelope modulation to "shape" the volume or harmonic content of the produced note in the time domain with the principle parameters being attack, decay, sustain and release. These are used in most forms of synthesis. ADSR control is provided by Envelope Generators.
• Low frequency oscillator (LFO) – an oscillator of adjustable frequency that can be used to modulate the sound rhythmically, for example to create tremolo or vibrato or to control a filter's operating frequency. LFOs are used in most forms of synthesis.
• Other sound processing effects such as ring modulators may be encountered.