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**preenfm2 and preenfm3 / Re: Newbie questions**

« **on:**March 21, 2016, 11:29:46 AM »

s^2 is a sin*sin so it's one octave above sin and should have a different spectrum too.

Sorry to necro the thread (even if it is my own), but it didn't seem worth making a new one.

I've been thinking about this, and sine^2 shouldn't have a different spectrum other than being an octave up (and having a DC offset, but you have highpass filters between the operators to filter that out).

When you ring modulate (i.e. multiply) two waveforms together, you get the sum and the difference of the frequencies present in the two waveforms. So for two sines you just get two frequencies in the output, the sum and difference of the inputs.

Example:

Two sines, 100Hz and 150Hz. If you ring modulate them together then your output will consist of a tone at 250Hz and a tone at 50Hz.

Another example:

Feed the same 100Hz sine into both inputs. The sum is 200Hz and the difference is 0Hz (which manifests as a DC offset).

So unless there is something else going on that would actually alter the spectrum, the S^2 waveform is just a sine an octave up. S^3 might be more interesting, that definitely has a different spectrum.