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Build: VODER Filter Bank

A 10-band bandpass filter bank matching the VODER patent (US 2,194,298). Each band uses two cascaded BiquadFilterNodes for 24 dB/octave rolloff (vs 12 dB/octave single stage), providing strong inter-band isolation essential for formant discrimination. Bands are non-uniformly spaced: six dense bands below 2 kHz cover the critical formant region (F1/F2), four wider bands above 2 kHz cover F3/F4 and fricative energy. Each band’s amplitude is controlled by a dedicated MIDI CC (CC20–29).

Step 1: Add band 0 (150 Hz)

Section titled “Step 1: Add band 0 (150 Hz)”

Two cascaded bandpass filters at 150 Hz provide 24 dB/octave rolloff. The gain node is controlled by MIDI CC20.

Nodes added: vf-flt-0a, vf-flt-0b, vf-amp-0, vf-cc-0

Connections: 3 new

Step 2: Add bands 1–5 (410–1700 Hz)

Section titled “Step 2: Add bands 1–5 (410–1700 Hz)”

Five bands covering the critical F1/F2 formant region, each with cascaded 24 dB/oct filters.

Nodes added: vf-flt-1a, vf-flt-1b, vf-amp-1, vf-cc-1, vf-flt-2a, vf-flt-2b, vf-amp-2, vf-cc-2, vf-flt-3a, vf-flt-3b, vf-amp-3, vf-cc-3, vf-flt-4a, vf-flt-4b, vf-amp-4, vf-cc-4, vf-flt-5a, vf-flt-5b, vf-amp-5, vf-cc-5

Connections: 15 new

Step 3: Add bands 6–9 (2320–6360 Hz)

Section titled “Step 3: Add bands 6–9 (2320–6360 Hz)”

Four wider bands covering F3, F4, and sibilant energy with cascaded filters.

Nodes added: vf-flt-6a, vf-flt-6b, vf-amp-6, vf-cc-6, vf-flt-7a, vf-flt-7b, vf-amp-7, vf-cc-7, vf-flt-8a, vf-flt-8b, vf-amp-8, vf-cc-8, vf-flt-9a, vf-flt-9b, vf-amp-9, vf-cc-9

Connections: 12 new

Step 4: Group into a module

Section titled “Step 4: Group into a module”

Select all 40 nodes and press g. Expose all 10 filter inputs and all 10 band outputs as ports.

What you just built

Section titled “What you just built”

A reusable VODER Filter Bank module with 0 exposed parameters and 20 exposed ports.

Select it in the Module Library (SPC m) to add one to any patch.

Next steps

Section titled “Next steps”