Originally Posted by Thorham
I keep reading this, but is it really true? Isn't it just the samples that are used?
This idea that the Amiga merely plays samples has to die!
The Amiga outputs arbitrary waveforms at arbitrary rates, somewhat filtered. Sometimes those waveforms come from samples of recorded sound and sometimes they are completely synthetic.
A two byte synthetic waveform of -128, 127, for example, will produce a somewhat filtered square wave. If a period value of 7159 is used, that square wave when output will have a fundamental frequency of 250 Hz. But it will also include many odd harmonics, too, like 750 Hz, and 1250 Hz and so on, well past 5KHz as the output jumps from -128 to 127 and from 127 back to -128.
The "grittiness" of the Amiga's sound comes from all these additional harmonics that are produced as the output jumps from one value to another. The more slowly the waveform is output, the more additional harmonics appear in the output EVEN IF THEY WEREN'T PRESENT IN THE ORIGINAL SAMPLE.