@audio/saturate-tape

Tape saturation — tanh transfer + playback HF rolloff (simplified machine model)

npm install @audio/saturate-tape

import tape from '@audio/saturate-tape'

Simplified tape-machine model: a mildly asymmetric tanh-plus-quadratic transfer (a milder even/odd blend than tube/transistor), followed by a one-pole low-pass standing in for playback-head HF loss (warmth sets the cutoff). Oversampled at the shaping stage (windowed-sinc up → shape → windowed-sinc down) to keep the extra harmonics from aliasing; the low-pass runs at the native rate afterward.

tape(data, { drive: 2, warmth: 0.4, fs: 44100 })
tape(data, { drive: 1.5, mix: 0.7 })

| Param | Default | | |---|---|---| | drive | 1.5 | pre-gain into the tanh+quadratic curve | | warmth | 0.25 | 0..1 — HF rolloff amount (higher = darker, more "tape") | | fs | 44100 | sample rate | | oversample | 4 | oversample factor for the shaping stage; 1 disables oversampling | | mix | 1 | 0..1 — wet/dry blend of the whole processed signal (shaping + rolloff) against the untouched input |

Mutates data in place and returns it (same array reference, not a copy). HF content rolls off measurably more than LF content at equal drive (≥3 dB more loss at 8 kHz vs 500 Hz in the family test suite) — the rolloff, not just the nonlinearity, is what reads as "tape."

Use when: darker, HF-rolled saturation — mix bus glue, vintage tape color. Not for: a bright, unfiltered harmonic signature (use tube/transistor/waveshaper, none of which touch the frequency response).

Part of the @audio/saturate family.

MIT © audiojs