GIC String Filter - first experiments (was: [sdiy] Filter Banks & CSound)

[Michael Baxter]

JH,

Way cool sound, amazing!

On the second sample, after the 40-bank GIC filter was turned on along
with the parametric, a little while in, the sound to me was distinctly
like a hammered dulcimer. Very nice rings and percussive timbres.

Best,
Michael

On Sat, 7 Feb 2004, jhaible wrote:

> Hi,
> 
> I've finally made my own version of a String Filter Bank.
> Samples from some first experiments are avaiable at
> http://home.debitel.net/user/jhaible/jh_string_filter.html
> 
> I think the peak/valley ratio of the main filter bank is ok,
> but the air/wood/bridge resonance needs some more
> adjustments. Any hints how to improove this are welcome.
> (Benade gives detailed information about the frequency -
> 125Hz, 175Hz, 1.5kHz and 2kHz for Cello -, but not
> about Q and Gain.)
> 
> JH.
> 
> 
> 
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Ian Fritz <ijfritz at earthlink.net>
> An: Tim Ressel <madhun2001 at yahoo.com>
> Cc: <synth-diy at dropmix.xs4all.nl>
> Gesendet: Mittwoch, 11. Dezember 2002 04:26
> Betreff: Re: [sdiy] Filter Banks & CSound
> 
> 
> > Tim --
> >
> > Filter bank references:
> >
> > "Electronic simulation of violin resonances," JV Mathews and J Kohut, J.
> > Acoust. Soc. Am., vol. 53, 1620 (1973).
> >
> > "Audio engineering improvements for clavichords," RW Burhans, J. Aud. Eng.
> > Soc., vol. 23, 635 (1975).
> >
> > "Filter bank design," IJ Fritz, Electronotes, #107, 16 (1979).
> >
> > "A 39-channel variable-Q filter bank," BA Hutchens, Electronotes, #115, 3
> > and #116, 3 (1980).
> >
> > It's the peak-to-valley ratio that mainly characterizes the overall
> > sound.  This ratio is strongly influenced by the shape of the resonance
> > curves and the number of resonators, since many long tails can add up to
> an
> > appreciable contribution.
> >
> > I used a single transistor circuit for my resonators -- just a phase-shift
> > oscillator with a bit of degeneration to set the Q.  I started with
> nominal
> > Q values around 20, but had to increase this somewhat to get 10 dB
> contrast
> > with all the bands turned up.  My design has variable amplitude on each
> > filter and variable Q in sub-banks of six frequencies.  That way I can --
> > for example -- do some formant shaping at low frequencies and timber
> > enrichment at high frequencies at the same time.
> >
> > The hollow, echoey sound you describe is from too large a peak-to-valley
> > ratio.  Several people have remarked on this before.
> >
> >    Ian
> >
> >
> > At 07:50 PM 12/10/2002, Tim Ressel wrote:
> > >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
> >
> >
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>