Sixteenths into a listening filter

The envelope filter earned its place in funk on documented records — the Mu-Tron-era clavinets and basses of the seventies, Stevie Wonder's "Higher Ground" chief among them — and the autowah chapter is honest about what this object is instead: a model of the Snow White AutoWah, a different, throatier circuit. You are not summoning a Mu-Tron; you are plugging into a very good pedal that listens the same way. The funk is in what it listens to — which makes this the one recipe where the settings table is half the story and your right hand is the other half.

Measured behavior cited below (the sweep law exact to the design, the RC release, the 250 Hz → ~2.5 kHz hardware span) lives in the pedal that listens and its validation notebook.

How to think about the knobs

Two of them are calibration, one is the personality:

• sensitivity matches the pedal to your source's level and your touch. Tune it so your normal hits open the filter halfway and your hard hits open it fully — the tanh knee compresses beyond that instead of slamming. Too high and everything pins; too low and the filter ignores you.
• bias and range set where the sweep lives: resting frequency and octaves above it. The defaults (250 Hz, 3.3 octaves) are the hardware.
• decay is the personality: how fast the filter falls back. Tens of ms is a wah articulation on every note — the funk setting. Hundreds is a swell that rides phrasing.

The patches

• The clav chop wants sixteenth-note playing with deliberate dynamic contrast — the filter turns your accents into vowels. mode 1 (bandpass, the circuit's other tap) is quackier and noticeably quieter; make it up with gain.
• The bass quack starts from the factory bass voicing (slot 2 — lower bias, tighter range, the GB pedal's instrument switch as a preset). Fingers, not pick, and let notes ring — the release is a real RC discharge (measured: a pure exponential, σ = 0.004) and it sounds like circuitry when you leave it room.
• The cocked wah is the secret mode: a fixed resonant filter with bias as a manual sweep — the parked-pedal midrange honk, and slot 4 ships it.
• direction 1 sweeps down from bias — the extension the pedal never had; reverse-envelope funk on a clean chop is startling.

The two patch points nobody uses enough

• The sidechain (right inlet): one sound wahs another. Kick → sidechain, pad → filter is the classic; a tap.808.seq~ row (through @pulse widened impulses) makes the filter sequenced while the pad sustains — an envelope filter with a drummer's timing.
• The envelope outlet (right outlet, 0..1 signal): the detector as a free modulation source. Scale it into tap.vco~'s FM inlet, a tap.vca~ gain, or a second filter — one performance, many destinations. (In bypass the outlet goes to zero, so tap it from a live instance.)

When to leave the recipe

• Your source has no dynamics. A static pad through an auto-wah is a static filter — feed the sidechain something rhythmic, or use tap.svf~ with an LFO and own the motion yourself.
• You want the filter on a knob. That's the cocked wah until you want morphing responses — then tap.svf~'s morph is the tool.
• You want the exact Mu-Tron quack. Raise resonance, try mode 1, and know the chapter's warning stands: you're modding a Snow White. The hardware A/B pass — the notebook cell waiting for the real pedal — will tell us precisely how far the model is from its own hardware, not from someone else's.