Autowah is an Effect block which creates a filter sweep in response to the volume of audio coming from any Source blocks it’s connected to.

Autowah is a post-effect. It processes the audio signal coming from any Source blocks connected to it by applying a ‘low-pass’ filter. The frequency of the filter is set in response to the volume of the audio signal. As this frequency sweeps up and down it creates the “wah” sound associated with a wah-wah pedal.

In the Autowah’s options, ‘Frequency’ is the lowest starting point for the filter sweep, ‘Range’ determines how wide the sweep is, and ‘Attack’ & ‘Release’ determine how sensitively the filter follows the incoming audio signal.

Outside of BlokDust, an Autowah may also be known as an envelope filter or envelope follower, among other names.

BlokDust’s Autowah uses the autowah component in the Tone.js framework. The Tone.js autowah is influenced by Tuna.js, an effects library for the Web Audio API.

Last updated: 16/04/2016


What is BlokDust?

BlokDust is a free to use web-based music making app. Build sounds or instruments and share your creations.

What is this?

This site serves as a wiki/user companion to, as well as a hub for tutorials and other related features.


Chrome browser recommended, desktop or tablet and an internet connection. If you have one, use a MIDI key controller for the best experience!