Pulse Width

Pulse width describes how a pulse wave divides each cycle between its high and low portions. At fifty percent the two halves are equal and the wave is a square, containing only odd harmonics; as the width moves away from that balance, the harmonic content shifts and the tone becomes thinner and more nasal. The real magic is pulse-width modulation, or PWM, where an LFO or envelope continuously varies the width. This makes the harmonics shift back and forth, producing a rich, animated shimmer from a single oscillator that can sound almost like two detuned voices. PWM is a classic technique for warm analog-style pads, strings, and basses, adding movement without the need for extra oscillators.