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 :
Guitar Extended 
Nice patch, how to control the LFO with a slider (let’s say from 0-127)?
Thanks
Hi Patrick,
You can delete [osc~], [+~ 1] and [*~ 0.5], and replace it with this :
[/ 127]
|
[pack 0 5]
|
[line~]
Change the settings of the slider to have a range of 0-127, and connect it to the [/ 127] object. Connect the [line~] to [*~ 1500]. That’s it.
Nice work, reminds me of an auto-wah project I coded while at uni. Silly bit obvious tip when working with frequencies in PD – keep the numbers within 0-127 range and use [mtof] or [mtof~] before the feed into the filter.
I’m liking your other projects very much too 🙂