[Stk] Wah-wah filter?

[Stephen Sinclair]

On Sat, Oct 5, 2013 at 1:23 AM, Robert Oschler <robert.oschler at gmail.com> wrote:
> Hello all,
>
> I'm a veteran C++ programmer but I am brand new to the STK.  Although
> somewhat math challenged I do know basic DSP principles.  Is there a
> built-in effect that creates a good Wah-Wah pedal effect?  If so,
> where do I start poking around to use it?  If not, are there some
> low-level filter effects I can use to build one?  Or do I have to go
> it alone and create a separate block of code that does the DSP
> operations necessary to create the Wah effect?:  Note, need it to be
> fast enough for real-time processing.
>
> http://en.wikipedia.org/wiki/Wah-wah_pedal
>
> For the guitarists out there, I want to create a truly solid Wah
> effect that really sounds like a mouth opening and closing around the
> sound, something with some body to it, instead of an adjustable cutoff
> filter that sounds more like someone simply twisting the Treble knob
> on a stereo (is there some resonance processing involved with
> achieving an enhanced Wah effect?).  I'm going to use the effect to
> process the sound output of my current STK waveform output.


Hi Robert,

So there's a bit of work out there on wah wah pedal modeling if you
search google scholar.  One that jumps out is Julius Smith's work
which specifically shows how to emulate the Cry Baby pedal, perhaps
it's of interest:

https://ccrma.stanford.edu/realsimple/faust_strings/faust_strings.pdf

In general (if i understand correctly) a wah wah pedal *is* just a
resonant low pass filter.  You might be able to use STK's TwoPole
class to implement it.

Not sure if that answers your question though, since I don't know
exactly what you mean by "something with some body to it."  (Not a
guitarist.)

By the way if you just want some good guitar effects and don't want to
implement it yourself I suggest checking out Guitarix:
http://guitarix.sourceforge.net/


Steve