/usr/share/puredata/doc/3.audio.examples/E04.difference.tone.pd is in puredata-doc 0.46.7-3.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | #N canvas 263 112 637 523 12;
#X obj 19 128 +~;
#X obj 18 209 output~;
#X text 141 3 NONLINEAR DISTORTION AND DIFFERENCE TONES;
#X obj 154 171 / 100;
#X floatatom 154 151 5 0 500 0 - - -;
#X obj 18 181 clip~ -1 1;
#X floatatom 42 81 5 0 0 0 - - -;
#X obj 18 155 *~;
#X obj 42 35 loadbang;
#X msg 154 127 50;
#X obj 154 103 loadbang;
#X text 385 494 updated for Pd version 0.37;
#X text 94 80 <-- frequency of second tone;
#X text 209 151 <-- before clipping;
#X text 234 134 amplitude of sum;
#X obj 18 9 osc~ 300;
#X msg 42 58 225;
#X text 99 226 This patch demonstrates how nonlinear distortion (also
known as "waveshaping") can create difference tones from a pair of
sinusoids. The sinusoids are initially tuned to 225 and 300 Hz \, a
musical fourth \, and have amplitude of 50 percent (0.5) so that the
sum is always less than 1 in absolute value. At these settings the
"clip~" object passes its input through unchanged.;
#X text 100 344 If the amplitude rises above 50 percent \, the clip~
object starts altering the signal nonlinearly \, and the result is
no longer as if the two sinusoids had been processed separately. Instead
\, they "intermodulate" \, finding a common subharmonic if one exists.
At 300 and 225 Hz \, the subharmonic is at 75 \, two octaves below
the upper tone and a twelveth below the lower one. Change the frequency
of the second tone and you will hear a variety of effects.;
#X obj 42 103 osc~;
#X connect 0 0 7 0;
#X connect 3 0 7 1;
#X connect 4 0 3 0;
#X connect 5 0 1 0;
#X connect 5 0 1 1;
#X connect 6 0 19 0;
#X connect 7 0 5 0;
#X connect 8 0 16 0;
#X connect 9 0 4 0;
#X connect 10 0 9 0;
#X connect 15 0 0 0;
#X connect 16 0 6 0;
#X connect 19 0 0 1;
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