[sdiy] Filter Banks & CSound

[Tim Ressel]

Ian,

Yes, in fact Dr. Matthews was mentioned in the
article. I'd love to see the article if you can lay
your paws on it.  What kind of filters are in your
filter bank? What frequencies and Qs??

By the by, the CSound filters I used did not seem to
parallel well. I didn't get that timbre change for
slight frequency changes. Also the bank had a hollow,
echo like sound. If I knew the real filters used I
might be able to get it working better.

--tr


--- Ian Fritz <ijfritz at earthlink.net> wrote:
> Hi Tim --
> 
> I have a 36 section fixed filter bank that I use all
> the time.  You  get 
> the most interesting results when your source has
> frequency vibrato.  The 
> bank causes different amplitude and phase modulation
> of the various 
> harmonics.  This is what produces the rich timbre of
> strings.  Tomita made 
> his string sections using multitracked recordings
> with different filter 
> settings. This timbral enrichment effect was
> originally researched by Max 
> Matthews in the late 1960's.  I can dig the
> reference up for you if you 
> like.  Ralph Burhans published filter bank designs
> in the middle 1970's.  I 
> used his frequency set which is based on frequency
> ratios of 2.1^0.2 (about 
> five filters/octave).  You need peak-to-valley
> ratios of around 10 dB.  You 
> can see my unit in the photo of my synth at my site.
> 
>    Ian
> 
> 
> At 02:31 PM 12/10/2002, you wrote:
> >To all,
> >
> >Recently I read an article by Bob Moog about
> >synthesizing strings using massive filter banks.
> Very
> >interesting stuff. Mr. Moog used a bank of 24 BP
> >filters from 150 to 8K spaced about 6 to the
> octave.
> >Not wanting to wire 24 filters just to try it out,
> I
> >decided to use CSound to experiment. So far the
> >results are not impressive. I think its due to the
> >type of digital filter I'm using.
> >
> >So let me put forth a question: Does CSound qualify
> as
> >DIY? Even though it's virtual, one does have to
> "wire"
> >an orchestra by hand. I'd like to post some results
> in
> >the future, but not if I'll be scorned for not
> using
> >real hardware  ;-)
> >
> >--tr
> >
> >
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