Pure Data comes with a set of filters useful in many different contexts. One of these filters is the [vcf~], a voltage-controlled band-pass filter. Its center frequency can be set by an audio signal, which means that it can be controlled by a LFO (Low-Frequency Oscillator).
I have made a patch that simulates a wha-wha pedal for guitar. It is controlled by a LFO, and is continuously sweeping the frequency range set by the user (as if the LFO were moving the expression pedal automatically). I’ll make another patch that can be controlled by a DIY footcontroller later on.
Play with the frequency range and the Q parameter to get sounds you’ll never get with a wha-wha stompbox.
- If necessary, you can download the patch here.
- Audio sample :