[sdiy] XOR ringmod

[Speth, John]

> >Are the XOR gate ring modulator designs a true ring mod 
> effect? in other 
> >words, if I put in 220Hz and 880Hz will I have sidebands at 
> 660Hz and 
> >1100Hz?
> 
> They're equivalent to ring modulating pulse waves. This means much
> more complex sidebands than if the carrier is a sine wave. Those
> sideband frequencies will be there along with frequencies due to all
> the harmonics in the pulse wave.

The downside to XOR ring mods is that even if one input is silent, the output will follow the other input.  This is not how an analog ring mod would work.  It does have a unique sound though and it's dirt cheap to implement.  I built an analog ring mod with a parallel XOR ring mod in the same panel and find it useful to have a choice.

Also, you can sub in any flavor of AND or OR gates with essentially the same effect with slightly different sound.  The bonus or downside here (depending on how you look at it) is that depending on where one input "ends up" when it goes silent, you may or may not get output when the other input is oscillating.

John Speth