[LAU] Frequency-response analyzer for Linux?

[Justin Smith]

On Tue, Jul 14, 2009 at 3:05 PM, Ken Restivo<ken at restivo.org> wrote:
> I have a couple DSP-for-dummies questions.
>
> I'm still intrigued by the idea of getting a proper Auto Wah-Wah sound going.
>
> I like the approach of building one out of LADSPA plugins.
>
> My question is this: what tools would I use on Linux to analyze the frequency response and characteristics of the many, many LADSPA filter plugins, so as to decide which has the response closest to a real wah circuit (i.e. a lowpass with a resonant peak just above the rolloff point)?
>
> What I'm going for is this:
> http://www.geofex.com/Article_Folders/wahpedl/wahped.htm
>
> I don't know squat about DSP, otherwise I might just try coding something up; the LADSPA spec looks pretty straightforward.
>
> -ken
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Try running a white noise source through the filter, then look at the
spectral graph output in your favorite spectrum analysis program.
Since white noise should have a flat spectrum, any peaks and valleys
in the output are those of the filter.