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A tall black pedal photographed face on, flecked all over with hand-flicked green paint spatters. The word quacker is painted across the middle in silver lowercase script. Two knurled silver knobs sit at the top corners with a small toggle switch between them, a tiny LED sits below the lettering, and a silver footswitch stands at the bottom.

Envelope Filter · One-off prototype

Quacker

Envelope Filter Available · 1 of 1

An auto-wah that plays itself off how hard you pick. Dig in and the filter jumps open; ease off and it stays shut. Green splatter over black, and it quacks exactly as much as the name promises.

  • TypeEnvelope filter (dynamic auto-wah)
  • ControlsAttack, Decay, Blend toggle
  • CircuitPedalPCB Duck Box Filter
  • Enclosure125B
  • Weight~8 oz
  • Power9V DC, center-negative
  • BuiltAug 2026
  • StatusAvailable - one of a kind
$185 free shipping Buy with Card Email to Buy Email to Buy

What it does

An envelope filter is a wah driven by your playing rather than your foot. The circuit watches how hard the note comes in and sweeps the filter in response, so the sound follows your dynamics: quiet notes stay dark and closed, hard ones open up into that unmistakable quack.

The Guyatone WR3 Wah Rocker that this is based on is the funk-record version of the idea - fast, vocal, and a little rude about it. Attack and Decay set the shape of the sweep and the Blend toggle decides whether you want the filter alone or the filter layered over your dry signal, which is the difference between an effect and a voice.

Best on single notes and tight rhythm playing, where the filter gets one thing at a time to react to.

Demo

Demo filmed by Onion Madder on the actual unit.

Controls

Attack
How fast the filter opens when you hit a note, and how sensitive it is to your picking hand.
Decay
How long it takes to fall shut again. Short is a percussive blip, long is a slow vowel that trails off.
Blend
Toggle. Mixes some of your dry signal back in, so the filter sits on top of the note instead of replacing it.

Circuit: Duck Box Envelope Filter (based on the Guyatone WR3 Wah Rocker). Built, painted, and finished by Onion Madder as an original one-off - not affiliated with, endorsed by, or a clone of any commercial brand.