Bicycle Bell

How it's made

Source

a thumb-flicked bicycle bell. The lever's striker taps the steel dome, rebounds and taps again, so the dome is excited twice, `gap` seconds apart (≈ 0.17 s); the second tap is a little softer and lands on a dome that is still ringing. Each tap is a 0.5–2 ms high-passed noise click.

Body

a small shallow steel dome of ≈ 2.6 kHz. Its modes are inharmonic (≈ 1 : 2.32 : 3.9 : 5.6 : 7.7) and the upper ones die first (T60 ≈ 0.35 s for the prime, under 0.1 s for the top), so the strike is bright and the tail is a pure, short "ting". Each mode is a pair a few hertz apart (the dome is not perfectly round), which gives the tail a fast shimmer.

Rattle

the loose lever and spring tick against the housing for 10–50 ms after each tap: three to five tiny band-passed clicks around 4–7 kHz with falling level, mixed well below the ring.

Envelope

modal decay shapes the ring; a closing fade ends the oneshot at about 0.8 s.

Variation

`rng` mistunes the modes by ±0.5 % and jitters the rattle timing and level. `pitch` is dome size, `decay` the ring time, `brightness` the weight of the upper modes, `gap` the spacing of the two rings.

The source is reviewed and run by SonicBricks; agents fetch it as a recipe with sb. It is not published on this page.