907a fixed filter bank

moog907a · filters · schema v1

907A Fixed Filter Bank (moogafakkin System 35 clone — categorized under Ports -> moogafakkin). Non-VC fixed filter bank: a high-pass + low-pass + several fixed center-frequency band-pass cells (12 dB/oct), each with its own level knob, summed to one output. Shares the moog-filterbank center-frequency lib with the 914. Own-code (textbook biquad bank). Beige moogafakkin faceplate (the intrinsic always-on look shared by the moogafakkin module family).

A recreation of the Moog 907A Fixed Filter Bank — the System 35's smaller fixed filter bank, a kind of fixed graphic EQ for spectral and formant shaping. The signal fans into ten parallel filter sections whose centre frequencies DO NOT move: a fixed low-pass shelf at the bottom, eight fixed band-pass sections marching up the spectrum (250 Hz, 350, 500, 700, 1 kHz, 1.4 k, 2 k, 2.8 k), and a fixed high-pass shelf at the top. Each section has its own LEVEL knob, and all of them sum to one output, so you sculpt a sound by boosting and cutting fixed regions — emphasise a formant, notch out a harsh band, or carve a vocal/telephone tone. Unlike a voltage-controlled filter the bands never move and there is no CV: it is a pure Web Audio biquad + gain graph (the larger 914 is the same module with twelve bands). At the default 0.5 every band passes at half level, a neutral middle you can boost or cut from.

the faceplate

1 inputs · 1 outputs · 2 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 signal to filter — fanned in parallel into every fixed filter section. audio signal

outputs

id	cable	what it does
`audio`	audio	The summed multi-band output — every section's contribution added together, the shaped spectrum. audio signal

params

id	label	range	default	curve
`hp`	HP	0..1	0.5	linear
`lp`	LP	0..1	0.5	linear

controls

control	what it does
Band1	Level of the fixed 250 Hz band-pass section (low mids / body). Defaults to 0.5.
Band2	Level of the fixed 350 Hz band-pass section (lower mids). Defaults to 0.5.
Band3	Level of the fixed 500 Hz band-pass section (mids). Defaults to 0.5.
Band4	Level of the fixed 700 Hz band-pass section (mids). Defaults to 0.5.
Band5	Level of the fixed 1 kHz band-pass section (presence). Defaults to 0.5.
Band6	Level of the fixed 1.4 kHz band-pass section (presence / nasal). Defaults to 0.5.
Band7	Level of the fixed 2 kHz band-pass section (upper mids / bite). Defaults to 0.5.
Band8	Level of the fixed 2.8 kHz band-pass section (high presence). Defaults to 0.5.
HP	Level of the fixed HIGH-PASS section at the top of the bank (corner ~6.6 kHz) — raise to add air and let the highs through, cut to tame them. Defaults to 0.5.
LP	Level of the fixed LOW-PASS section at the bottom of the bank (corner ~175 Hz) — raise to add weight and lows, cut to thin the bottom. Defaults to 0.5.

source

moog907a.ts on GitHub.