[sdiy] Yet another try at explaining beat tones, etc.

[Donald Tillman]

   > From: "Jerry Gray-Eskue" <jerryge at cableone.net>
   > Date: Fri, 5 Jun 2009 08:20:03 -0500
   > 
   > From this I gather that common sound creation and reproduction
   > systems such as guitar and speakers are basically linear and so
   > do not create any secondary signals.
   >
   > I am still a bit fuzzy on what Makes a system non-linear so to
   > clarify lets use a Voltage Control Amplifier.

You are absolutely not going to clarify the concept of linearity with
guitar and VCA examples, as they are both famous for their
nonlinearities.  I mean, sheeshe, you might as well be using porn to
explain virginity.

The most important thing about linear systems is that they obey
"Superposition" while nonlinear system do not.  

Superposition is, very specifically, where if you have two input
signals available, A and B, the output of the system when you apply
A+B to the input is exactly equal to the output of the system's
response to A-only plus the system's response to B-only.

Likewise, the linear system's response to X times signal A is exactly
equal X times the system's response to the original singal A.

That's it, everything else follows from there.

  -- Don

-- 
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com