> On Fri, Jul 17, 2009 at 4:47 PM, Ken Restivo wrote:
> > On Tue, Jul 14, 2009 at 04:13:13PM -0700, Justin Smith wrote:
> >> On Tue, Jul 14, 2009 at 3:56 PM, Fons Adriaensen wrote:
> >> > On Tue, Jul 14, 2009 at 03:25:39PM -0700, Justin Smith wrote:
> >> >
> >> >> 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.
> >> >
> >> > For a more 'musical' analysis, use Japa. It has either
> >> > a logarithmic or perceptual frequency scale. Pink noise
> >> > source is built-in, and if you set the analyser response
> >> > to 'Proportional' it will show a flat spectrum for pink
> >> > noise. It can also show the difference between two spectra,
> >> > e.g. input and output of a filter, and this produces much
> >> > more stable displays when using a noise test signal.
> >> >
> >> > For the filter, you could try on of the four Moog VCF
> >> > plugins I wrote years ago. Apart from the resonant
> >> > lowpass they will also add some juicy distortion at
> >> > high levels, as does the original Moog filter and
> >> > probably all real analog Wah processors. Frequency
> >> > control is logarithmic, which is probably what you
> >> > want, and there are separate control inputs to
> >> > set the static frequency and resonance and their
> >> > modulation. One problem could be that the modulation
> >> > inputs require audio rate signals (the filter were
> >> > designed for use in AMS) but that can be changed
> >> > easily if you want. If you want to play with them
> >> > use AMS.
> >> >
> >> > But Japa and the filters to be found at
> >> >
http://www.kokkinizita.net/linuxaudio/downloads
> >> >
> >> > The filter plugins are in the MCP set.
> >> >
> >> > --
> >> > FA
> >>
> >> I used japa years ago, but forgot its name, thanks for this excellent
> >> piece of software, which I am excited to have rediscovered.
> >
> >
> > Mille grazie! I've got JAPA going on two platforms, but I've got to apologise for being a bit dense in figuring out how to use it.
> >
> > The UI looks a bit like an HP oscope, but, alas, i'm not much of an engineer, so I'm not sure to start. Is there a quick simple tutorial somewhere on how to use it? Anyone care to give me a few sentences of advice?
> >
> > I basically want to put white noise through some filters (prolly using JACK-RACK), and view the frequency response of it. Looks like JAPA already has a built-in white an pink noise generator, which is nice. What would I connect to what (using i.e. using jack_connect) and how would I set up the switches and control on JAPA to do this? A simple screenshot of the correct setup might be enough to get me going.
> >
> > Thanks again!
> >
> > -ken
> >
>
> Connect the pink output of japa to the input of the application with
> the filter, connect the output of the app with the filter back into
> japa, the curve you see in japa will be the frequency response of the
> filter. Since japa can overlap displays, you can also try putting some
> musical material through: one input straight into japa, one through
> the filter first, and look at the compared spectrums.
>
> Another possibility would be routing the japa pink output to an analog
> wah pedal, and comparing the frequency response of the analog pedal
> coming back in to the digital wah emulator. Or you could compare the
> spectral output of the real and digital wahs with musical input.
