[Stk] Wah-wah filter?

[Perry Cook]

I especially like the end result of Julius' experiments 
with his CryBaby:

The estimated Q values printed at the end are
Q = [9.4, 4.0, 1.9],

and the estimated pole frequencies are
fp = [464, 838, 2252] Hz. 

This, plus other data from that article, pretty much 
sets you up to use a 2pole resonator, and just interpolate 
between (and beyond) those values.

Think ill code this up in ChucK this afternoon!!

Prc


Sent from my iPad :-)

On Oct 5, 2013, at 7:32 AM, Stephen Sinclair <sinclair at music.mcgill.ca> wrote:

> 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
> 
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