Every synth, however complex, is built from four blocks: an oscillator that makes a tone, a filter that removes part of it, an envelope that shapes it over time, and an LFO that moves something automatically. Learn those four and you can navigate any synth you open.
An oscillator generates a repeating waveform. The classic four:
- Sine — pure fundamental, no harmonics. Sub bass, soft leads.
- Triangle — a few odd harmonics, quiet. Soft flutes, mellow bass.
- Square / pulse — odd harmonics, hollow and woody. Reedy leads, chip-style bass. Narrowing the pulse width makes it thinner and nasal.
- Sawtooth — all harmonics, brightest and buzziest. Strings, pads, supersaws, aggressive bass.
Rule of thumb: pick a bright waveform and subtract, rather than a dull one and try to add.
Most synths give you two or three oscillators. Detuning the second by 5–12 cents thickens the sound. Setting the second an octave below (-12 semitones) adds weight; a fifth up (+7) adds a synthetic sheen.
The filter removes frequencies above or below a cutoff point. Two controls do most of the work:
- Cutoff — where the filtering starts. Lower it on a saw wave and you get a darker, rounder tone.
- Resonance — a boost right at the cutoff point. A little (10–20 percent) adds character. A lot creates the whistling, vocal quality you hear in acid basslines.
Filter slopes are measured in dB per octave. 12 dB/octave is gentle and musical; 24 dB/octave is the classic aggressive analogue sound.
The ADSR envelope decides how the sound behaves from keypress to silence. The single most important distinction:
- Percussive: attack 0 ms, decay 100–400 ms, sustain 0, release short. Plucks, stabs, basses.
- Sustained: attack 200–1500 ms, sustain high, release 500–2000 ms. Pads, strings.
Most synths let you route a second envelope to the filter cutoff. This is where synths get expressive: a filter envelope with a fast attack and a 300 ms decay gives you the classic "wow" opening at the start of each note.
A low frequency oscillator is an oscillator running too slowly to hear, used as a control signal. Common destinations:
- Pitch, at around 5 Hz and a small depth — vibrato.
- Filter cutoff, slow (0.1–0.5 Hz) — a sweeping, breathing pad.
- Amplitude — tremolo.
- Pulse width — constant movement in a square wave, cheap and very effective.
| Patch | Oscillators | Filter | Amp envelope | Movement |
|---|
| Warm pad | 2 saws, detuned 8 cents, one at -12 | Low-pass, cutoff around 2 kHz, low resonance | A 800 ms, D 1 s, S 80 percent, R 1.5 s | LFO to cutoff at 0.2 Hz, plus reverb |
| Sub bass | 1 sine, or sine plus saw high-passed at 300 Hz | Low-pass around 400 Hz on the saw layer | A 0 ms, D 200 ms, S 90 percent, R 100 ms | Filter envelope, small decay |
| Lead | 2 saws detuned 15 cents, plus square an octave up | Low-pass around 5 kHz, resonance 15 percent | A 5 ms, S 100 percent, R 200 ms | Vibrato LFO at 5.5 Hz, delayed onset |
Start from an init patch, not a preset. You learn nothing by tweaking someone else's 40-parameter patch. A single saw through a low-pass filter teaches you more in ten minutes.
Design in context. A pad soloed sounds thin and disappointing; the same pad under a vocal sounds right. Always audition against the rest of the track, and mix as you design.
Related reading: layering sounds, writing basslines, and neural audio synthesis explained.
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