Boss Warning Siren

How it's made

Source

an electronic alarm siren, a pair of slightly detuned band-limited saws plus a square one octave below, switching between two pitches; underneath, a heavy machine drone (saw pair + sub sine at pitch / 8).

Body

the siren passes a low-pass that tracks the note (cutoff ≈ 3.5 × f, Q 1.2), so each note is buzzy but never shrill; the drone is low-passed near 240 Hz with a slow cutoff wobble, which gives a growling, unsteady mass without any harsh resonance. A soft tanh stage adds a few odd harmonics, like an overdriven speaker.

Envelope

every note is a 20 ms swell to full level that relaxes to ~40 % before the next note, which makes the alarm pulse; pitch glides between the two notes in ~25 ms so there are no steps or clicks. The drone fades in over 0.4 s, throbs at the note rate, and everything fades out over 0.25 s after the last note.

Variation

`pitch` and `interval` set the two alarm notes (a tritone is the most menacing, a fourth the most formal); `stepTime` and `cycles` set pace and length; `rng` only detunes the drone pair by a few cents.

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