@audio/eq-crossover

import crossover from '@audio/eq-crossover'

A designer, not a filter — it takes no audio buffer and processes nothing. Given N-1 crossover frequencies it returns N per-band SOS (second-order-section) cascades built from digital-filter's Linkwitz-Riley design, low band to high, ready to feed a biquad engine.

LR order ≡ 2 (mod 4) — LR2, LR6, ... — needs one output inverted per crossover point to sum flat; order ≡ 0 (mod 4) — LR4, LR8, ... — sums in-phase already (Linkwitz & Riley, JAES 24(1), 1976). That inversion is applied internally, so the bands crossover returns already sum flat when added in the time domain — no extra polarity handling needed at the call site.

import { cascade } from '@audio/biquad'

let bands = crossover([500, 2000], 4, 44100)  // 2 freqs → 3 bands: low, mid, high
let low = cascade(data.slice(), bands[0])
let mid = cascade(data.slice(), bands[1])
let high = cascade(data.slice(), bands[2])

Use when: multiway speaker/DSP crossovers, multiband compression band splits — anywhere bands must sum back to flat.

Part of @audio/eq — the eq family umbrella.

MIT © audiojs