Three real EQ archetypes, one curve, no decoration. Pick a band, move it, and watch the same move behave differently depending on which family is under your hand. The line on the canvas isn't a drawing of an idea, it's the filter maths, evaluated at every frequency on the axis.
This is a real four-band filter, run through the same maths a mixing console or a plugin runs. The curve you see is computed from the filter coefficients directly, not painted on. The spectrum behind it's your loop, live, before and after. These are archetypes, not a model of any specific unit. They teach the behavior. Your own EQ supplies the color.
Every band holds the Q you dial, at every gain. What you set is what you hear and what you see, nothing else moves.
Low Shelf. Everything below the frequency knob moves together. This is the one that decides how much low end the mix has to carry.
A gentle 2x-oversampled tanh stage after the whole chain, the "warms up a channel strip" move. Off by default so the curve you see is the EQ alone.
Same corner frequency, two different ways to make the top end louder. Shelf turns up energy that's already there. Excite high-passes the dry signal at that same frequency, drives it through a saturator, and adds back only what that generates: harmonics that weren't there before. Loudness matched, so what changes is the character, not the volume.
Shelf. A plain high-shelf boost at the high band's frequency. Clean, and exactly as bright as the boost dial says.
What this prototype isn't: it doesn't save presets, it doesn't export a curve, and the
compare section shares the lab's own high-shelf band rather than running an isolated instance, so
switching it changes the main curve too. Full notes in LAB_EQ_NOTES.md.