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Official effect

Q-Filter

Resonant low-pass sweep that currently uses the same LFO wah core as Classic Wah.

The current path is the same one used by Classic Wah and Cry Filter: a sine-modulated resonant low-pass sweep with a post-filter high shelf. In other words, it behaves as a swept wah today rather than as a separately tuned fixed-Q resonant filter.

  • Filter, Wah & Envelope
  • Library #69
  • Preview 8s

Waveform preview

Static peaks come from the compiled FAUST preview render. The live scope is drawn from the browser playback output in real time.

Timeline
0:00 / 0:08
Source
Compiled browser preview
Live oscilloscope from the browser playback output.AnalyserNode keeps the signal path unchanged while exposing the waveform.

How It Works

Technical view

The current path is the same one used by Classic Wah and Cry Filter: a sine-modulated resonant low-pass sweep with a post-filter high shelf. In other words, it behaves as a swept wah today rather than as a separately tuned fixed-Q resonant filter.

  • Filter, Wah & Envelope
  • band-pass filtering
  • waveshaping / saturation
  • delay processing
  • oscillator / LFO modulation
  • DC blocking

Signal Path

Compiled preview chain

Preview source: An internally generated picked-string phrase is widened to stereo with a 19-sample right-channel delay and slight left/right shelf-EQ offsets before it hits the filter core.

  1. 1internal picked-string demo phrase
  2. 2stereo spread with a short right-channel delay
  3. 3modulated resonant low-pass sweep
  4. 4post-filter high-shelf tone shaping
  5. 5dry / wet mix
  6. 6DC blocker
  7. 7output gain trim
  8. 8final tanh limiter

Preview source

An internally generated picked-string phrase is widened to stereo with a 19-sample right-channel delay and slight left/right shelf-EQ offsets before it hits the filter core.

Effect core

Sine-LFO-modulated resonant low-pass filter with post-filter high-shelf tone shaping.

Signal path

The static waveform and the live player both reflect this compiled signal chain.

  • internal picked-string demo phrase
  • stereo spread with a short right-channel delay
  • modulated resonant low-pass sweep
  • post-filter high-shelf tone shaping
  • dry / wet mix
  • DC blocker
  • output gain trim
  • final tanh limiter

Controls that matter

These are the currently active controls detected in the FAUST source for this effect.

  • mix: Blends the untouched stereo preview source with the filtered path after the effect core.
  • output_gain_db: Applies final post-effect level trim after DC blocking and before the output limiter.
  • focus: Sets the base center frequency of the resonant low-pass sweep and also shifts the post-filter high shelf.
  • motion: Increases the sweep depth and resonance of the low-pass filter.
  • rate: Sets the speed of the internal sinusoidal sweep that modulates the filter center.

Code-backed analysis

The generated description is tied to the active helper blocks and routing found in the current DSP.

  • demo
  • fx
  • outputStage
  • leftDemo
  • rightDemo
  • filterCore
  • phraseMono
  • previewShiftSamples

Controls

Audible controls in this DSP

  • mix

    Active

    Blends the untouched stereo preview source with the filtered path after the effect core.

    Lower settings preserve more dry attack and full-band tone; higher settings emphasize the filter treatment.

  • output_gain_db

    Active

    Applies final post-effect level trim after DC blocking and before the output limiter.

    Matches loudness without changing the filter behavior itself.

  • focus

    Active

    Sets the base center frequency of the resonant low-pass sweep and also shifts the post-filter high shelf.

    Moves the wah voice lower or higher and changes how open the top end feels afterward.

  • motion

    Active

    Increases the sweep depth and resonance of the low-pass filter.

    Makes the effect more vocal, deeper, and more resonant as it rises.

  • rate

    Active

    Sets the speed of the internal sinusoidal sweep that modulates the filter center.

    Changes how quickly the wah or filter cycles through its sweep.

Analysis

Code-derived notes

Current implementation shares the same LFO-driven resonant low-pass wah core as Classic Wah and Cry Filter.

Active blocks

  • demo
  • fx
  • outputStage
  • leftDemo
  • rightDemo
  • filterCore
  • phraseMono
  • previewShiftSamples
  • pickedVoice
  • fund
  • pickEnv
  • ampEnv
  • triggerAt
  • maxDelaySamples

Inactive helpers

  • synthVoice
  • organVoice
  • bellVoice
  • softsat
  • quantize
  • combLP
  • echoOnly
  • diffuser

Warnings

No current warnings are attached to this effect.

Source

  • library/filter-wah-envelope/q-filter.dsp
  • Output stage: DC blocker -> output gain trim -> final tanh limiter
  • Library position: 69

More In Filter, Wah & Envelope

Continue through the library

Each effect page uses the same generated description pipeline and compiled waveform preview assets.

Classic Wah

Resonant low-pass wah with an LFO-driven sweep for a steady vocal-style filter arc.

View How It Works

Envelope Filter

Reactive envelope low-pass sweep that currently uses the same detector-driven core as Auto Wah.

View How It Works

Formant Filter

Three-band formant bank with an LFO-driven vowel position for moving voice-like color.

View How It Works