Low-pass

A clean low-pass built from one to six cascaded one-pole stages, with selectable slope and no resonance control.

What it does #

Low-pass smooths rapid changes and removes frequencies above Cutoff. Slope selects the number of cascaded one-pole sections, making it useful for straightforward spectral filtering or for smoothing control signals without resonant coloration.

Controls and ports #

Audio In is processed by Cutoff and Slope/Pole count; Audio Out returns the low-passed signal. It has no Resonance or Drive controls.

Practical uses #

• Remove high-frequency content from audio when a clean non-resonant roll-off is enough.
• Smooth stepped modulation, random values, gates, or envelope discontinuities.
• Use more poles for stronger separation and fewer poles when preserving transient shape matters.

Things to know #

• More poles increase both attenuation above Cutoff and phase delay around it.
• The implementation compensates Cutoff by sqrt(poles) before cascading so the displayed corner remains useful across slopes.
• A low-pass on a control signal acts as lag/smoothing; it is the same frequency-domain operation applied to slower data.
• There is no resonance or nonlinear saturation in the recovered core.

Technical details #

A high-confidence Nitro implementation candidate supports the technical summary, but the visible-module mapping remains inferred.

The matching filter/BWLPF body cascades poles one-pole low-pass sections at 4x oversampling. It converts pitch to f = 440*2^((p-69)/12)*sqrt(poles), uses a limited cubic tangent approximation for prewarping, calculates G = g/(1+g), and runs the signal through up to six calcLP stages. The sqrt compensation differs in sign from BWHPF because the cascaded low-pass corner moves the opposite way. The body contains no resonance, Drive, or limiter.

Nitro port	Type
in	InputAudioPortType
freq	InputAudioPortType
poles	InputValuePortType
out	OutputAudioPortType

Open questions #

• Measure all visible Slope settings, nominal dB/octave values, displayed Cutoff calibration, phase, and gain at the corner.
• Fit the step response for control-signal smoothing and verify smoothing, stereo independence, latency, and sample-rate scaling.
• Confirm the wrapper's pole range, automation behavior, and response at minimum/maximum Cutoff.

Version and sources #

Checked against Bitwig Studio 6.0.6. This page combines Bitwig's module metadata, the existing Grid course and guides, and Nitro analysis where the mapping is strong enough to support a technical statement.

Related material #

• Grid Modules course reference

Return to Bitwig Grid Modules or the Grid Modules course lesson.