Transformer Hum

How it's made

Source

continuous magnetostriction of a large transformer core at twice the 50/60 Hz mains rate. A phase-coherent sine bank supplies 100/120 Hz and ten decaying harmonics; mains leakage is quieter.

Body

tank panels emphasize broad regions near 230 and 520 Hz; laminated cores add upper partials. Low-level pink vibration filtered at 180 and 460 Hz (Q 1.3/2) supplies non-tonal casing texture.

Envelope

energized steady state, without a switch transient or a fade to silence. The 8 s loop contains whole mains cycles and 1, 2 and 3 cycles of slow load modulation; engine crossfades noise.

Modulation

0.25/0.375 Hz amplitude sidebands suggest faint beating without detuning the mains grid. Upper harmonics move slightly more than the bass; a 0.125 Hz load cycle barely changes the body.

Layers

centered core and mains leakage, quiet panel vibration and narrow stereo cooling air. No electrical arcing, tonal whistle, room reverb or high-frequency fizz is part of this sound.

Variation

seeded partial phases and noise; mains selects 50/60 Hz, load raises upper harmonics, casing shifts panel emphasis, beating sets sideband depth, cooling sets the subdued air layer. Presets cover oil-filled 50 Hz, loaded 60 Hz, exposed dry laminations and a muffled enclosure.

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