[sdiy] Filter Banks & CSound

[Ian Fritz]

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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