Auto Filter
A low-pass filter driven by an LFO.
AvailableEffect
Auto Wah
A resonant filter driven by your playing level.
About
A resonant peak pushed up the spectrum by the signal's own level. Play harder and it opens, the funk wah that tracks dynamics instead of a clock.
Presets
Start from a named sound, then adjust the instrument to make it yours.
InitDefault
Signal graph.
ExperimentalA sketch of the signal path, in the order of the parameter groups.
How it works.
An envelope follower measures the input's level, and that measurement sets a resonant peak's centre frequency. Loud pushes the peak up toward Base Freq raised by Octaves, quiet lets it fall back to Base Freq. Nothing here runs on a clock, the sweep exists only while you are playing, and its shape is the shape of your dynamics.
The three remaining controls split cleanly between the detector and the filter. Sensitivity offsets the level at which the follower tops out, which is how you match the pedal to how hard you actually play; Q and Peak Gain shape the peak itself, deciding how narrow it is and how far it protrudes.
Web Audio has no envelope-follower node, so the browser preview builds one: a waveshaper rectifies the input, a one-pole lowpass at about 8 Hz averages it, and the result drives the filter's detune through a scaling gain. That is a genuine audio-rate follower, not an AnalyserNode polled from an animation frame, which would update only about once every 16 ms and smear exactly the transients a wah exists to track. Driving detune rather than frequency also makes the sweep exponential for free, so the same octave span sounds the same wherever Base Freq sits.
