[sdiy] SSM2164 to use as ring modulator...

[David G Dixon]

I simulated this circuit from the LM13700 datasheet, and it didn't seem to
be all that flash.

My suggestion would be to build a 2164-based VC crossfader, and normal one
of the CV inputs to the inverse of the other CV input.  Then it will
automatically be a ringmod whenever only one CV is plugged in, and you get
two modules in one.

I believe that Malekko did exactly this with their XMIX or something (I may
have the company and the module name wrong -- too lazy to confirm right
now). 



> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Neil Johnson
> Sent: Friday, February 14, 2014 3:14 AM
> To: Olivier Gillet; synth-diy
> Subject: Re: [sdiy] SSM2164 to use as ring modulator...
> 
> Hi Olivier,
> 
> > I'm curious about how this could be achieved with just a linear VCA.
> > By adding a DC offset to the modulator so that it remains positive, 
> > and then removing the corresponding fraction of the carrier 
> from the 
> > output?
> 
> Yes, its a technique that's been known and used for at least 30 years.
>  Check the LM13700 datasheet, e.g. figure 27:
> 
>     http://www.ti.com/lit/ds/symlink/lm13700.pdf
> 
> Or this magazine article on page 8:
> 
>     http://www.idea2ic.com/LM13600/UsingOTAs2.pdf
> 
> Note: www.idea2ic.com is the website of Don Sauer, one of the 
> two designers of the LM13700.
> 
> Neil
> --
> http://www.njohnson.co.uk
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