[sdiy] Karplus-Strong overblowing?

[Josh Nursing]

If you haven't noticed:

It's Digital Waveguide (Network  or not), not 'Waveguide Digital Networks'.

The order matters. There's something else called Waveguide Digital Filters,
but it's different tech, different purpose.

Josh

On Sun, 4 Jan 2026 at 11:41, Mike Bryant <mbryant at futurehorizons.com> wrote:

> Actually from JOS
> "A *Digital Waveguide <http://en.wikipedia.org/wiki/Waveguide> Network* (DWN)
> consists of any number of digital waveguides interconnected by scattering
> junctions
> <https://ccrma.stanford.edu/~jos/pasp/Scattering_Impedance_Changes.html>"
>
> However  the term outside of audio is Digital Waveguide Mesh.
> ------------------------------
> *From:* Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Josh
> Nursing via Synth-diy <synth-diy at synth-diy.org>
> *Sent:* 04 January 2026 16:24
> *Cc:* Synth DIY <synth-diy at synth-diy.org>
> *Subject:* Re: [sdiy] Karplus-Strong overblowing?
>
> The term is Digital Waveguides not 'Waveguide Digital Networks'. J.O.S. is
> definitely the Canonical reference online although there's a massive amount
> of maths involved in his texts.Perry Cook also does some very good texts on
> those types of structures including wind instruments.
>
> Get the structure right, and you'll probably find that the overblowing
> behaviour is then totally emergent from the model itself.
>
> DWs were used in Yamaha VL1 and VP1 (later VL70m too) AFAIK.
>
> It's fun stuff with particularly interesting tones for me but I do not
> necessarily look for emulative acoustic tones but rather
> Synthetic/Electronic tones with some 'material / structural realism'
> built-in. In other words, 'Syncoustic'.
>
> Regards,
>
> Josh
>
> On Sun, 4 Jan 2026 at 09:03, Mattias Rickardsson <mr at analogue.org> wrote:
>
> Richie  -  Good points about the need of nonlinearities and the advice
> about Waveguide Digital Networks.
>
> Overblowing should result in octaving behaviors, right? Then it's not
> enough to suppress the fundamental, but all the odd partials should get
> weaker and the even ones (the next octave) get stronger. Some nonlinearity
> then needs to favor the even ones.
>
> /mr
>
>
>
>
> Den lör 3 jan. 2026 13:48 <rburnett at richieburnett.co.uk> skrev:
>
> The original KS model is very basic as others have said. It really just
> models a single "round trip" delay with some (frequency-selective)
> damping and possibly some dispersion in the loop. That's fine for
> modelling things that are struck or plucked with transients like
> strings.
>
> I believe wind instruments are more accurately modelled by Waveguide
> Digital Networks. These are networks of bi-directional delay lines
> coupled together by "scattering junctions." The scattering junctions or
> nodes determine how much of the output of one delay line couples into
> the next, how much reflects back into the original delay line
> (propogating in the opposite direction,) and how much is absorbed (lost
> to heat, radiated, whatever.)
>
> Then at the ends of the model you have non-linearities that control how
> the pressure waves interact with the Reed and blowing pressure at the
> blown end of the instrument, and the outside air pressure at the, erm,
> bell end ;-))
>
> I think its these non-linearities at the ends that will be critical for
> modelling overblown behaviour.  The overall model must be non-linear if
> the behaviour changes when the amplitude of the excitation changes.
> Otherwise the strongly blown sound wound just be a louder, but otherwise
> identical, version of the softly blown sound. There wouldn't be a shift
> to a different resonant mode when over-excited.
>
> Waveguide Digital Networks and physical modelling aren't really my
> thing, so i wont say any more as could be misleading or plain wrong. I'd
> do some reading of the physical modelling literature by Julius Orion
> Smith if you're into the theory. Or alternatively string together some
> delay lines and play about with scattering nodes, filters and
> non-linearities at the ends if you're into the practical/coding side.
> "Reed tables" appear to be one way to model the non-linear behaviour of
> the reed to pressure differences.
>
> I hope this is some help. Interested to read other's comments and
> suggestions.
>
> -Richie,
>
>
> >>> Am 02.01.26 um 10:56 schrieb cheater cheater via Synth-diy:
> >>>> Does Karplus-Strong synthesis allow for overblowing? Are there any
> >>>> modifications to it that allow it?
> >>>>
> >>>> Overblowing is when you blow into a reed instrument too hard and
> >>>> essentially the fundamental becomes much weaker and the higher
> >>>> partials become much stronger, kind of "overdriven".
> >>>>
> >>>> Thanks
> >>
> >>
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