## [Audacity-nyquist] Amplitude Modulation Distortion

 [Audacity-nyquist] Amplitude Modulation Distortion From: paul beach - 2010-12-14 02:36:41 ```Amplitude Modulation Distortion The engineering formula for A.M. is (1 + m sin A) * sin B What usually happens is that a signal radiates into the gate of a FET and we have, for example: exp(sin A + sin B + ....) This spews out harmonics, since 2nd, 3rd, .... powers of sine become 2nd, 3rd, ... harmonics. (sin A + sin B + ...) * (sin A +sin B ...) ... * If only second order terms are considered, the power series can be rearranged, filtered (apparently) and then put into the form at the top of the page. This can be used to generate an overtone series, if the sines are harmonically related, to start with. I use the fundamental plus third partial, for example: (sim (sine 60) (sine sine 79)) The equal temperament should not be a problem, for 'perfect' fifths. For Two Part Invention 14, it sounds like so: http://www.climatehoax.ca/music/two_part_14.mp3 ;nyquist plug-in ;version 1 ;type generate ;name " A. M. Instrument..." ;action "A. M. sounds..." ;control p "Pitch" int "Frequency" 69 11 111 (defun crick () (bandpass2 (mult 2 (s-exp (mult 2 (sim (sine p) (- 0.0 .5) (sim 1 (mult (/ 18.0 p) (sine (+ p 19 ))))) )) (pwl .005 1 (/ 8.0 p) (/ 8.0 p ) 1) ) 1200 (/ p 44.0 )) ) (notch2 (lowpass2 (crick) (* 2.0 p)) 220 2) -- paul beach sniffyraven@... ```