Serge Waveshaper was Re: Harmonics question

Sean Costello costello at
Wed May 20 19:49:52 CEST 1998

At 09:59 PM 5/19/98 EDT, you wrote:
>In a message dated 5/19/98 3:52:56 PM, magnus at wrote:
>>I recall seeing diagrams of such unlinear waveshapers. I even think
>>that we have discussed this several times. For instance do I recall
>>that the Serge waveshapers would do odd and even harmonics and that
>>the schematic is very simple indeed.
>Hi Magnus
>I wonder if you're confusing the Serge Triple Waveshaper with the Wave
>Multiplier module. One waveshaper is a very simple circuit based around one
>quarter of an LM 3900 and does non-linear "Harmonic Reduction" (unlike
>anything done in music theory). It is similar to a CA 3080 tri-to-sine
>converter I believe.

The Triple Waveshaper does two things:  it converts a sawtooth wave to a
triangle wave (via full wave rectification), and converts that into a sine
via, um, breakpoint...diode...thingies...(man, I wish I knew the lingo).
The amount of rectification is voltage controlled, as described in Serge
Tcherepnin's patent.

>The Wave Multipliers do some nutty half and full wave rectification (I
>believe) and have a whole lot of chips. The sound to me is very much what I
>would expect from the timbre modulator circuits in the oft mentioned
>Electronotes and in Barry Klein's book. I would never attempt to build one,
>too complicated for a timid sole such as me. Now if some one offered some kits
>of these circuits...

As far as I can guess, the Wave Multiplier works as follows.  (This subject
has come up a lot, but the Wave Multiplier is one of my big obsessions,
along with Moog filter distortion, the Barberpole phaser, and washing the
germs off of my hands several hundred times a day so they stop sending my
brain radio waves).

The first section is a simple clipping amplifier, that "rounds" the signal.
Possibly a CA3080 that is overdriven.  The amount of overdrive is voltage

The second section is...well, no one really seems to know (prove me wrong,
folks!). It seems to work as follows: When the signal voltage reaches
certain thresholds (positive or negative), the signal "wraps around."  Easy
to do in digital (the Nord Modular implements it, and it sounds GREAT), but
I don't know how to do it in analog. 

The third section is four voltage-controlled full-wave rectifiers in series
(see the Serge patent for details).  Probably uses all four sections of a

Any more details, folks?

Sean Costello

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