Instruments · glossary
Synthesizer
Also called synth, synthesiser
A synthesizer is an electronic instrument that generates its own sound with circuits or software, then shapes it with controls such as filters and envelopes. Synths come as keyboards, desktop modules, computer plugins and phone apps.
A synthesizer, or synth, generates its sound as you play, starting from a simple electronic wave. An oscillator makes a raw wave that repeats at the pitch of the note. A filter then darkens or brightens it, and an envelope (ADSR) sets how each note starts and fades. An LFO adds slow, repeating movement such as vibrato. Most knobs on a synth set one step of that chain, and a saved set of knob positions is called a patch.
One wave can go a long way. Play a sawtooth on A2 (110 Hz), close the low-pass filter about halfway, and set decay to about 200 ms with sustain at zero: that is a plucky bass. Keep the same sawtooth, set attack to 1 second and release to 2 seconds, add reverb and hold A3, C4 and E4, and it becomes a slow pad.
Synths differ in how they make the raw sound. A subtractive synth starts with a bright wave and filters part of it away. FM synthesis has one wave change the pitch of another so fast that you hear a new tone, which suits bells and electric pianos. A wavetable synth sweeps through a set of stored wave shapes.
The RCA Mark II, installed at Columbia University in 1957, filled a room and read its music from a punched paper roll. Robert Moog introduced his modular synth in 1964, and his Minimoog of 1970 was the first synth sold in retail stores, with the keyboard built in. Yamaha’s DX7 of 1983 was the first commercially successful digital synth and the first synth to sell more than 100,000 units.
Most beginners now meet synths as apps and plugins, where the same controls show up as on-screen knobs and sliders. Many hardware synths have no speakers, so they need an amp or headphones. MIDI lets one keyboard play another synth or an app. Gelato Synth, our iPhone app, is an FM and wavetable synth that gives each part of the sound its own page (Osc A, Osc B, FM, Noise, Env, Filter, LFO, Space) and plays from pads that hold only the notes of a scale in place of a keyboard.
How a synthesizer works goes through every knob in order, and types of synth sounds shows what each family of sounds is built from. For apps to try, see the best synth apps for iPhone.
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