Sunday, July 5, 2015

pd29. Triangle Wave generation using Wavetable Synthesis in Pure Data

Similar to the last example, we will create a triangle wave. This time we store one period in a table.


The name of the table is triangle and we have a view of the table in the middle of canvas. It is of size 512, and the message of sinesum creates a wave composed of fundamental (f) , and partial 3f, and partial 5f. There are only odd frequencies in a triangle wave. We used these amplitudes: 0.5,-0.5/9 and 0.5/25 for the three sinusoids.


We use tabosc4~ to play the wave over and over with 4-point interpolation. A wave at a frequency of 440-Hz, can fit exactly 440 such waves in one second. One second corresponds to 44100 samples. Thus each period is 44100/440 samples, or about 100. The program pd will figure out the exact math and do any interpolations, since it is not exactly 100, but 100.227.


The mono audio shows the triangle waveform:


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