Harmonics question

Steve daedalus at tezcat.com
Wed May 20 07:04:00 CEST 1998


>>Simple experiment to get a waveform with only even harmonics:
>>
>>Take an odd harmonics waveform (Say at 880 Hz) add a sine at 440 Hz
>>and voila! You just got yourself an all-even harmonics waveform.
>>I don't think that it will sound particularly earth-moving, but yeat
>>usefull. If you synk or PLL the odd-harmonics waveform to be at the
>>double frequency of the sine you can get it to track up better.
>
>-has anyone ever tried taking a function with only odd harmonics and
>subtracting it from another function of the same frequency to increase the
>strength of its even harmonics? would have to add the fundmental back in
>afterwords though, i suppose..
>Ethan Duni

Well, the strength of the odd harmonics in the subtracted function would
have to be exactly the same as in the initial function, and it would have
to be phase-correct too.  If you have the means to do this, then you
probably also have the means to just strengthen the even harmonics in the
initial signal.  There's another surefire way to increase the even
harmonics: clipping.  As the amount of clip increases, the signal becomes
more similar to a square wave.

In a related vein, awhile back I was involved in a discussion about
generating PWM on a sampler.  The method used was playing back a saw-up and
saw-down wave at the same frequency, with a LFO modulating the pitch of one
of the saws by a very small amount (around .25 Hz).  The result is a pulse
wave with varying DC offset.  The problem was getting the LFO speed and
depth set such that the pulse width didn't get too close to zero.


******************************
If you can't be the pearl, be the grain of sand.
******************************






More information about the Synth-diy mailing list