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

[harrybissell]

LOL...

no. I have a whole TUBE of LM3900 and only a few BBD.  I just began to understand the
true nature of the 3900 as current controlled voltage source... a real useful block.
Imagine
my surprise to hear Bob Pease slam the chip as a piece of sh!t (my original opinion
btw).

I guess the principle and practice of the chip do not match well... and it is indeed a
crappy
"opamp" if you call it that.  The ARP filter is really brilliant, imho.

There is a "Dual Norton"  (LM359 iirc) which I have not tried, Bob Pease did not have
an opinion on that one. Its not real cheap like the 3900.

H^) harry

mark verbos wrote:

> Harry has the Lm3900 surpassed the BBD as you most hated chip?
>
> harrybissell wrote:
>
> >To boldly go where some men have gone before (but not in quite some time :^)
> >
> >Ralph W. Burnhams did a project in the early 70's using multiple BPFs made from
> >(yuck) LM3900s... it was published in the Journal of the Acoustical Society of
> >America
> >or the Audio Engineering Society...
> >
> >...sorry I forgot which. He had like 40 filters as well...   I'll see if I still
> >have the photocopies
> >and get some dates
> >
> >Another of his projects was "TTL devices for monophonic synthesis" which may have
> >inspired the WASP design
> >
> >H^) harry
> >
> >Cynthia Webster wrote:
> >
> >
> >
> >>on 2/7/04 4:35 PM, Michael Baxter at mab at cruzio.com wrote:
> >>
> >>
> >>
> >>>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
> >>>
> >>>
> >>Great Job Jurgen!
> >>
> >>Delightful, those same "rings and percussive timbres"!
> >>
> >>Cynthia
> >>
> >>
> >>
> >>>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
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >
> >
> >
> >