[Stk] Wah-wah filter?

[Perry Cook]

Of course!  I'll post in both ChucK and STK groups.

PRC

On Oct 6, 2013, at 3:31 PM, Robert Oschler wrote:

> Hello Perry,
> 
> Will you be posting the results?
> 
> Robert
> 
> On Sun, Oct 6, 2013 at 2:48 PM, Perry Cook <prc at cs.princeton.edu> wrote:
>> 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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> 
> 
> 
> -- 
> Thanks,
> Robert Oschler
> Twitter -> http://twitter.com/roschler
> http://www.RobotsRule.com/
> http://www.Robodance.com/