C4RBN

WMD 4HP
FILTER VCF WAVEFOLDER DISTORTION

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4HP 4/2-pole state-variable filter with input saturation and output wavefolder. Simultaneous LP/BP/HP 2-pole outputs plus a switchable-mode 4-pole output. Includes PING envelope for vactrol-style pluck.

Patch Ideas · 6

★ Pinged vactrol bass
RES near self-osc · close FREQ low · no IN signal · clock-derived trigger to PING · take 4P (LP mode) · results in plucky pitched bass tones with natural decay
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: C4RBN, Clock, Sequencer, Output. Signals: 1 audio, 1 pitch, 1 trigger.C4RBNClockSequencerOutputRES: ~3 o'clockFREQ: low4P mode: LPPINGtrigV/OCT1v/oct4PaudioOuttrigPitch1v/octInaudioaudiopitchtrigger
★ Screaming fold lead
audio through IN · SAT cycled to stage 3 · FOLD enabled · RES high · envelope to FM via attenuverter · take 4P for overdriven folded lead
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: C4RBN, VCO, Envelope, Output. Signals: 2 audio, 1 cv.C4RBNVCOEnvelopeOutputSAT: stage 3FOLD: onRES: high4P mode: BPINaudioFMcv4PaudioSawaudioOutcvInaudioaudiocv
★ Parallel LP/HP notch
mix LP and HP 2-pole outputs to external mixer with HP inverted · pseudo-notch with resonance peak at cutoff · FM attenuverter sweeps with bipolar LFO
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 5 connections. Modules: C4RBN, VCO, LFO, Mixer, Output. Signals: 4 audio, 1 cv.C4RBNVCOLFOMixerOutputINaudioFMcvLPaudioHPaudioOutaudioOutcvIn 1audioIn 2audioOutaudioInaudio11. invert at mixeraudiocv
Sine VCO for FM
RES fully past self-osc · IN unpatched · V/OCT from sequencer · BP output as sine carrier · feed second VCO into FM input for filter-FM
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: C4RBN, VCO, Sequencer, Output. Signals: 1 audio, 1 cv, 1 pitch.C4RBNVCOSequencerOutputRES: self-oscFREQ: midV/OCT1v/octFMcvBPaudioOutcvPitch1v/octInaudio11. audio-rate FMaudiocvpitch
Synchrodyne fold bass
4P mode LP · FOLD on · RES moderate · slow envelope to FREQ via FM · SAT stage 2 on input · fat folded bass with harmonic bite as filter opens
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: C4RBN, VCO, Envelope, Output. Signals: 2 audio, 1 cv.C4RBNVCOEnvelopeOutput4P mode: LPFOLD: onSAT: stage 2RES: noonINaudioFMcv4PaudioSubaudioOutcvInaudioaudiocv
Stereo 2-pole spread
LP out hard-left · HP out hard-right · shared modulation to FM · creates phantom center with cutoff-dependent stereo width
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: C4RBN, VCO, LFO, Mixer. Signals: 3 audio, 1 cv.C4RBNVCOLFOMixerINaudioFMcvLPaudioHPaudioOutaudioOutcvLaudioRaudioaudiocv

Behaviors

Simultaneous 2-pole outputs always active on LP/BP/HP jacks

The first 2-pole core outputs LP, BP, and HP simultaneously — pick multiple responses for sum-and-difference or stereo-spread patches without retracking cutoff.

Series 4-pole path take signal from 4P output

The 4P jack is the output of a second 2-pole stage fed in series from the first, yielding a steeper 4-pole response. Its mode (HP/BP/LP) is independent from the 2-pole outputs.

Vactrol-style ping gate/trigger at PING input

PING injects a fast-decay exponential envelope directly into cutoff, emulating a Low Pass Gate. With resonance near self-oscillation, yields plucky pitched tones without a patched envelope.

Self-oscillating sine VCO RES past 3 o'clock with no audio at IN

Filter self-oscillates as a clean sine. V/OCT input tracks over useful range — turns C4RBN into a sine VCO for pinged bass or FM carriers.

Staged input saturation hold FOLD/SAT button

Four discrete saturation levels at the filter input — from clean (level 0) to aggressive drive. SAT CV input adds continuous modulation on top of the chosen step.

Output wavefolder press FOLD/SAT (FOLD LED on)

Folds the 4P output post-filter. With high resonance or self-oscillation, adds screaming harmonics reminiscent of the Synchrodyne. Only affects 4P — 2-pole jacks stay clean.

Delayed 4P mode switch hold HP/BP/LP button

LED reflects selection immediately, but the audio mode only changes when the button is released — useful to line up a filter-mode change on the beat during live performance.

Controls

Global FREQ Manual filter cutoff frequency.
2.5Hz – 10kHz · 1V/Oct tracking · temperature compensated
Global RES Filter resonance. Self-oscillates past 3 o'clock, generating a clean sine.
Adds to RES CV input
Global FM Inverting attenuator for the FM input. Scales cutoff CV bidirectionally.
CCW: invert · noon: zero · CW: unity · exponential response
Global FOLD/SAT Button Press toggles the 4P output wavefolder (FOLD LED). Hold cycles 4 input saturation levels (SAT LED).
Saturation: 4 stepped levels · wavefolder post-4P core
4P output HP/BP/LP Button Cycles 4-pole filter mode between HP, BP, LP. LED updates immediately; audio switches on release when held.
Indicated by HP/BP/LP LEDs

I/O

IN · 6

  • IN 20Vpp range · 100kΩ impedance AUDIO
    Audio input. Passes through the input saturator before hitting the first 2-pole core.
  • V/OCT 1V/Oct · 82kΩ · temperature compensated CV
    Calibrated exponential CV input for keytracked cutoff.
  • FM >100kΩ CV
    Exponential cutoff CV input, scaled by the FM attenuverter.
  • RES >100kΩ CV
    CV for resonance. Sums with the RES knob.
  • SAT >100kΩ CV
    CV for input saturation amount. Adds to the stepped SAT setting.
  • PING Gate/trigger GATE
    Gate/trigger input. Fires a fast-decay vactrol-style envelope into cutoff.

OUT · 4

  • LP 20Vpp · 1kΩ
    2-pole low-pass output of the first filter core.
  • BP 20Vpp · 1kΩ
    2-pole band-pass output of the first filter core.
  • HP 20Vpp · 1kΩ
    2-pole high-pass output of the first filter core.
  • 4P 20Vpp · 1kΩ
    Series 2nd 2-pole filter output. Mode selected via HP/BP/LP button; optional wavefolder post-filter.