Radio Tune Sweep

How it's made

Source

a superheterodyne dial being turned. Each station carrier mixes with the receiver's local oscillator; the audible product is the difference tone |f_dial - f_station|, a whistle that falls to zero beat as the dial reaches a carrier and rises again as it passes. Between stations the speaker plays band-limited static.

Body

a small speaker and cabinet: the audio is band-passed to roughly 280 Hz - 5 kHz with a mild mid-range emphasis; static is pink noise through a moving band-pass so the hiss "tunes" with the dial.

Envelope

the dial position follows an eased curve (fast flick, slow approach to the last station). Static swells between stations and ducks near each carrier; the whistle fades out while the beat is below about 150 Hz so no sub-audio thumps or clicks remain. The sound ends on a quiet carrier hush.

Variation

`stations` sets how many carriers are crossed, `rng` jitters their positions and the noise; `brightness` moves the speaker band and whistle range, `hiss` balances static against whistles.

Space

none; the sound is dry so a scene can add its own room.

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