923 filters / noise source

moog923 · filter · schema v1

923 Filters / Noise Source (moogafakkin System 35 clone — categorized under Ports -> moogafakkin). White + pink noise outputs PLUS a fixed filter utility on an external audio input: independent low-pass and high-pass taps with LO PASS / HI PASS cutoff knobs (log-mapped ~40 Hz-20 kHz). Own-code (noise generator + biquad filters). Beige moogafakkin faceplate (the intrinsic always-on look shared by the moogafakkin module family).

A recreation of the Moog 923 Filters / Noise Source — a dual-purpose utility panel from the System 35. It does two unrelated jobs at once. First, a NOISE SOURCE: white and pink noise generators on two independent outputs, both scaled by one LEVEL knob — the raw material for percussion, wind, snare bodies, and sample-and-hold. Second, a simple FIXED FILTER section: one external audio input fanned into a low-pass and a high-pass filter, each with its own corner knob and its own output, so you can split a signal into low and high bands or just tame one end. The noise and the filter share no signal path — they are bundled on one panel for convenience. It is pure Web Audio (looping noise buffers + two biquads), no worklet.

the faceplate

1 inputs · 4 outputs · 3 params

about this module

Hover a control, or open the patch panel and hover a jack.

inputs

id	cable	what it does
`audio`	audio	The external signal fed through the filter section — it fans into BOTH the low-pass and the high-pass at once (the signal being filtered, not a modulator). audio signal

outputs

id	cable	what it does
`white`	audio	Full-spectrum white noise, scaled by the LEVEL knob — equal energy per Hz, bright and hissy. audio signal
`pink`	audio	Pink (1/f) noise, scaled by LEVEL — −3 dB/octave, warmer and more natural-sounding than white, good for wind and rumble. audio signal
`lp`	audio	The audio input passed through the LOW-PASS filter, corner set by the LO PASS knob — the low band of the input. audio signal
`hp`	audio	The audio input passed through the HIGH-PASS filter, corner set by the HI PASS knob — the high band of the input. audio signal

params

id	label	range	default	curve
`level`	Level	0..1	0.8	linear
`lpCutoff`	Lo Pass	0..1	0.5	linear
`hpCutoff`	Hi Pass	0..1	0.5	linear

controls

control	what it does
Hi Pass	The HIGH-PASS corner for the filter section's HP output. The 0..1 knob maps log across ~40 Hz to 20 kHz; raise it to thin the HP output, lower it to let more low end through. Defaults to 0.5.
Level	Master gain on BOTH noise taps (white and pink) — sets the loudness of the noise outputs together. Does not affect the filter section. Defaults to 0.8.
Lo Pass	The LOW-PASS corner for the filter section's LP output. The 0..1 knob maps log across ~40 Hz to 20 kHz; lower it to darken the LP output, raise it to let more through. Defaults to 0.5.

source

moog923.ts on GitHub.