[PD] Equalizer

[Miller Puckette]

I also recommend Thomas Musil's IEMLIB which has the best filters
you can get for Pd.

cheers
Miller

On Tue, Aug 28, 2001 at 11:55:43AM +0200, pix wrote:
> On Tue, 28 Aug 2001 02:42:12 +0200 (CEST)
> Álvaro Castro <alvcastro at yahoo.es> wrote:
> 
> > Hi all!!
> > 
> > Some days ago I posted an e-mail asking for help for
> > building an equalizer. I didn't get many help, that's
> > the reason I write again. If I'm writing to the wrong
> > list, please tell me.
> > I just want to know the basics of an equalizer so I
> > can start working. As you see, I'm a beginner, but I
> > don't know how to start.
> 
> the main reason you probably haven't received much help is because this is
> not really a pd question but a general dsp question. so ideally you would
> look into some dsp resources, where you will find that you need to know a
> fair amount about digital filtering to make an equalizer, then maybe you
> would get some help on building filters in pd.
>  
> > I choosed to learn PD instead of other sound programs
> > or programming languages because I thought it was very
> > powerful and not very difficult to learn.
> > But when I started working with PD I discovered that
> > one of the most important things for me (the low and
> > high pass filters) don't work very powerfully. I tried
> > filtering a sample and I realized that the filters
> > didn't cut TOTALLY the frequencies they just decreased
> > the amplitude a little bit.
> 
> this is common with digital filters... to get a really sharp roll off you
> normally need a more complicated filter... you can also try recursively
> applying the same filter...
> 
> > Finally, I would like to know what's the best way to
> > work with pure (or almost pure) frecuencies. That's
> > the reason I want to build an equalizer. I would like
> > to add, increase, delete or decrease specific
> > frecuencies. Is that posible with Pure-data??
> 
> well, adding frequencies is easy... [osc~] and [+~] :)
> 
> > Thank you very much for your time!
> > I will appreciate any answer, because I don't know
> > what to do now!!
> 
> there is a dsp book available for download at www.dspguide.com, it's
> reasonably accessible as an introductory text.
> 
> pix.