[sdiy] Wave Multiplier-like circuits?

[Kyle Stephens]

Adam, a few leads:

See example VI here:

http://www.uni-bonn.de/~uzs159/

Yves Usson of YuSynth has a wavefolder based on a Juergen Haible design:

http://yusynth.net/Modular/index_en.html

Here's JH's original page:

http://www.jhaible.de/jh_wavefolder.html

Nothing like running your mix through a stompbox either!

Which if you wana do mid-patch, Ken Stone has a designs for interfacing guitar-level gear with synth signal levels:

http://www.cgs.synth.net/modules/cgs60_sba.html

Good luck, HTH!


_Kyle


--- On Mon, 10/26/09, John Richetta <jrichetta at earthlink.net> wrote:

> From: John Richetta <jrichetta at earthlink.net>
> Subject: Re: [sdiy] Wave Multiplier-like circuits?
> To: "Synth DIY" <synth-diy at dropmix.xs4all.nl>
> Date: Monday, October 26, 2009, 11:30 PM
> On Oct 26, 2009, at 8:55 PM, Adam
> Schabtach wrote:
> > One of my favorite modules is Ken Stone's Wave
> Multiplier. I love the range
> > of timbres it produces from a single oscillator input
> and the way it
> > responds in interesting ways to control voltages.
> Hence I'm interested in
> > finding other circuits that do similar things, and
> would be delighted if
> > anyone has any to recommend to me.
> > 
> > <snip>
> > 
> > Thanks in advance for any suggestions that anyone
> would like to provide.
> 
> Being a not-so-literate amateur hack, who prefers to create
> from scratch, I don't much know about other published
> circuits.  I am fairly sure this topic has been
> discussed before on this list, however, so do the obvious
> searches, if you haven't.  But this is a topic of
> interest and an ongoing area of exploration for me (on the
> rare occasions I have time for electronics), so, here are
> some general inspirations of mine, from somewhat specific to
> very vague:
> 
>    - piecewise nonlinearities: break up a
> signal into bands (by voltage range, say), and do different
> things in each band; combine different sign/scale versions
> of the original in each band, and sum; shift the limits,
> gain, etc. for successive bands based on what you "learned"
> about a signal in an earlier one, or based on envelope
> following, or other interesting controls; the obvious
> approach to bands is to make them hard-edged, but consider
> using smooth windowing instead (more difficult, obviously)
> 
>    - use any nonlinear regime of your
> favorite semiconductor device, though some are better than
> others, to distort one or more applied signals; my favorite
> types of curves are smooth but changing "knees," "bumps,"
> and "wiggles" where you can smoothly shift which part of the
> curve is used to distort the "signal" input, by adding more
> or less control signal (or attenuating and then
> re-amplifying it - harder); level conversion before and
> after nonlinear processing is usually necessary; if you care
> about DC coupling, or tightly controlled gain, or output
> that's mostly free of thumps and DC offsets, this problem
> gets appreciably harder
> 
>    - create complementary transformations
> that are at least approximately inverses of one another,
> transform a signal, insert some other conventional
> processing (ex., filter), and then un-transform the result;
> try to avoid requiring perfect matching of the complementary
> transforms :) - this usually amounts to using
> not-too-extreme nonlinearities
> 
>    - depending on what you use to combine
> linearities, you can achieve nonlinear results; balanced
> multipliers and transconductance amps are useful building
> blocks (though some argue this is "cheating" :) ); if you
> have useful nonlinearities, try to discover some judicious
> ways to blend them - nonlinearly, perhaps - using some other
> control, maybe derived from the signal itself; split, shift,
> and scale, ala wavelets
> 
> Apologies for deliberately being very nonspecific, but I
> hope these basic hints might encourage you to invent
> something interesting.  For me, at least, a lot of the
> fun is thinking up a flexible idea (which usually must also
> past the test of being mathematically nontrivial, for it to
> be musically worthwhile or interesting), and then refining
> it until it works.
> 
> Have fun, good luck, and enjoy the sound.  -jar
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