[pd] shaper filter

padawan12 padawan12 at obiwannabe.co.uk
Wed Feb 7 14:45:39 CET 2007

On Wed, 07 Feb 2007 00:16:18 +0100
Malte Steiner <steiner at block4.com> wrote:

> actually there was never a Kawai K2000, only K1,K3,K4, K5 and K5000 (and 
> another K1, K1 II or something like that)

Yeah I had both K5 and K1 for a while. If I remember correctly K1 was 4 part
per voice, just 4 static spectra with an envelope for each and you could 
modulate two of them together which made some neat ringmod type effects.

It was advertised as an easier to program version of the K5, but in fact
it was nothing like it. The K5 had some really fancy breakpoint envelopes
that were very flexible, with a kind of matrix to assign each env to one
or more groups of sinewaves. It needed plenty of time and patience to program
but made some sounds that were unrivalled at the time.

I also get those mixed up. The K2000 was a Kurtzweil now I recall, a
development of the K1000 additive synthesiser. That one really had 
individual sines and was quite a beast.

> > "The resonant filter is actually an FIR Comb filter with very tight
> > bands. In addition, it is pre-programmed with an envelope shape for a
> > really dynamic sweeping effect."
> > 

Ah yes, that would be lush to follow up an additive stage with. Placing the
bands at some ratio (a/b * f) of the harmonics would make them all pop in
and out in some sequence when you sweep it. Follow that up with a bit of
delay and you have a very sparkly sound.

> so something with bandpass filters would be great, which are used for 
> formant filters and vocoders. Have you checked out the Lattice filter 
> object?
> Of course these approaches are not as precise as resynthesis but have a 
> destinct sound without the additive sparkle. I am about to create a 
> morphing filter synthesizer with some bandpasses in pd with the Emu 
> Morpheus in mind. Although they interpolate the filter coefficients to 
> create the dynamic morph.

Sounds great, look forward to hearing that one.

> Can the biquad or FIR objects do this? How 
> dynamic are they, I nether tried them...

No. Well not by interpolating the coefficients directly. It will
go unstable and blow up at lots of places. You need to do the interpolation
of the parameters before the intermediate stage variables. But that's
not very expensive. 

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