How Does It Work?#

VCF is a compact state-variable filter that gives you lowpass, bandpass, and highpass outputs at the same time from one audio input.

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Quick Overview#

• VCF is a three-output filter module.
• It uses one shared filter core with simultaneous LP, BP, and HP taps.
• The cutoff range is 20 Hz to 20000 Hz.
• Resonance ranges from 0 to 1.
• The panel is intentionally minimal: one large cutoff control, one smaller resonance control, two CV inputs, and three outputs.

Inputs And Outputs#

Port	Type	What It Does
In	Audio	Source signal for the filter core.
Cut	CV	Modulates cutoff frequency.
Res	CV	Modulates resonance.
LP	Audio	Lowpass output.
HP	Audio	Highpass output.
BP	Audio	Bandpass output.

Controls Reference#

Control	Range	Default	Behavior
Cutoff	20..20000 Hz	1000 Hz	Sets the filter frequency.
Res	0..1	0	Sets resonance in the shared filter core.

Output Taps#

• LP is the lowpass output.
• BP isolates the resonant band around the cutoff.
• HP is the highpass output.
• All three outputs update together because they come from the same state-variable process.

CV Behavior#

• Cut uses exponential modulation, which makes it suitable for pitch-like tracking and wide sweeps.
• Res uses linear bipolar modulation and is clamped to the 0..1 range.
• The DSP smooths both parameters before calculating the filter state.

Panel Layout#

• The large top knob is CUTOFF.
• The smaller knob below it is RES.
• FREQ and Q CV inputs sit above the audio section.
• The bottom row is IN, LPF, BPF, and HPF.