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Ring mod octave up vs full wave rectification. 
raccoonboy 
Are they the same thing or different?
I know often with ring you dial the original signal back in but sill they give different results? 

mskala 
Different things, similar but not identical effect.
In particular, note that the fullwave rectifier output, abs(sin(x)), has sharp points at the bottom and is rounded at the top. The ring mod output, sin(x)**2, is smooth at both top and bottom. The ring mod is producing just DC and twice the input frequency  that is, the sum and difference of the input frequency with itself  whereas the fullwave rectifier produces a more complicated spectrum with a lot of harmonics. And these differences may become more significant if the input is more complicated than a sine wave. 

raccoonboy 
mskala wrote:  Different things, similar but not identical effect.
In particular, note that the fullwave rectifier output, abs(sin(x)), has sharp points at the bottom and is rounded at the top. The ring mod output, sin(x)**2, is smooth at both top and bottom. The ring mod is producing just DC and twice the input frequency  that is, the sum and difference of the input frequency with itself  whereas the fullwave rectifier produces a more complicated spectrum with a lot of harmonics. And these differences may become more significant if the input is more complicated than a sine wave. 
interesting thanks... What do you mean by 'DC', you mean it has a DC offset because it is now positive? Definitely going to try them both and compare the differences they have on audio. I assume the ring will have a lot less noise/harmonics but I guess it depends how they react to a moving signal. I'm going to assume one will be better than the other for i.e. doubling a bass signal, although maybe they are both good in different ways.. Only one way to find out I guess. 

mskala 
raccoonboy wrote:  interesting thanks... What do you mean by 'DC', you mean it has a DC offset because it is now positive? 
Yes. The average voltage is not zero, so if you split it up into sinewave components, one of those components has to be zero frequency, which is a DC offset. That is the case for both the ringmod and rectifier outputs.
The reason I emphasized that was to show how it comes from the ring mod's "sum and difference frequency" thing. You're taking the sum and difference of a frequency f with itself. So f+f = 2f and that's the higheroctave component, and ff = 0 and that's the DC component. 

Graham Hinton 
raccoonboy wrote:  Are they the same thing or different?

They are not only different, but they are both special cases of what the two devices do and both can do a lot more, especially when used together.
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