I recently got a Bela ( http://bela.io/
) and was wanting to have a good wah modeler.
I had a first thought to copy the CCRMA wah from Guitarix, but it occurred to me that since it is a model based on a curve-fit to the GCB-95 it's a one-trick pony without directly intuitive ways to apply different voicings of variant circuits.
I sat down and worked out the transfer function and digitized it via bilinear transform. The resultant code allows you to enter resistor and capacitor values directly with potential to create loadable presets.
As such I thought I would share it as a possible feature set to add to the Guitarix wah. Here's where it can be found: http://cackleberrypines.net/transmogrifox/src/bela/inductor_wah_C_src/
The following 2 files are the whole of it:
It's coded in C, but it would be trivial to convert this to a class so it doesn't look out-of-place in a C++ & faust repository.
The .zip file is the Bela project, which won't be useful for Guitarix.
Under the Analysis folder is a test program which generates a set of frequency response curves and impulse responses so you can compare and tweak with real circuits if more fine-tuning is desired.
Here's the set of frequency response plots for the Vox V847 voicing:http://cackleberrypines.net/transmogrifox/src/bela/inductor_wah_C_src/Analysis/Vox_V847_Response.png
(BBCODE tags for image resize don't appear to work on this board, so you will have to just click the link)