Online Synthesizer

How the Online Synthesizer works

Online synthesizer: oscillator

The oscillator is the raw sound. A sawtooth contains every harmonic and is the brightest and most common starting point; a square has only odd harmonics and sounds hollow and woody; a triangle is soft with weak upper harmonics, and a sine is a single pure tone with nothing for the filter to remove. Pulse is a square with a narrow duty cycle, nasal and reedy. Fat saw stacks three detuned sawtooths for the thick chorusing sound of eighties lead and pad patches; the detune slider widens the spread. On the other waveforms detune shifts the whole pitch by up to fifty cents, half a semitone, which is how you would tune one synth against another.

Filter

The low-pass filter removes harmonics above the cutoff frequency, which is what makes the technique subtractive. Sweep the cutoff down and a sawtooth turns from buzzy to muffled to a near sine. Resonance boosts the harmonics just below the cutoff; at low values it adds presence, at high values it whistles and can self-oscillate, and sweeping the cutoff with resonance up is the sound of a thousand acid house records. The filter here is a 24 dB per octave ladder-style slope, the steep kind found on the classic analogue monosynths.

Envelope

The envelope controls how loud the note is over time. Attack is how long it takes to reach full volume after the key goes down, decay how long it takes to fall from there to the sustain level, sustain the level held while the key stays down, and release how long the sound takes to fade after the key is lifted. A plucked sound has an instant attack, short decay, zero sustain and short release; a pad has a slow attack, high sustain and a long release. The graph above the keys redraws as you move the sliders.

Echo and playing

Echo is a feedback delay of 300 milliseconds with the slider setting how much of the delayed signal is mixed in. Up to eight notes sound at once, so chords work. The left and right arrow keys shift the keyboard an octave; the lower row starts at the octave shown in the readout and the upper row an octave above it.

Related tools