>just off the top of 1 databasz.



Distortion


By applying some nonlinear processing to your Sounds, you can add extra
harmonics to the output,
making it spectrally richer. This is the technique behind things like
frequency modulation, ring modula-tion,
waveshaping, and even cranking your guitar amp beyond the range where it
has a linear response
- all in an effort to broaden the spectrum and avoid those pure, yet
boring, sine waves.
Waveshaping
The key to producing distortion in a signal is to process it in a nonlinear
way. Demonstrate this to yourself
right now by opening up WS distortion. A Waveshaper uses the value of its
Input as the index into the
wavetable named in ShapingFunction.
Try out a linear shaping function by setting the ShapingFunction parameter
to FullRamp. FullRamp
is a straight line from -1 up to 1. To see FullRamp, hold down the Command
or Control key and click
the disk button next to the ShapingFunction field; FullRamp looks like a
straight line. Now select WS
distortion, and choose Oscilloscope from the Info menu. Use a MIDI keyboard
to play the harp sample
and look at the waveform.
Next, try changing the ShapingFunction to WinSine4. Hold down the Command
or Control key and
click the disk button in order to see what the WinSine4 wavetable looks
like; this is definitely not a
straight line. Then select WS distortion and choose Oscilloscope from the
Info menu. Play some low
notes on the MIDI keyboard and look at the difference in the shape of the
waveform being displayed on
the oscilloscope.


Clipping
Waveshapers are not the only way to apply a nonlinear process to a signal.
One really simple way is to
simply turn it up too loud. This clips the signal, and introduces sharp
edges (and thus new harmonics) in
the waveform where before there were only smooth curves.
Take a look at sub-fundamental distortion. Notice that your sound here is
fed into a Gain and that the
Gain is set to 10. Select the Gain, choose Oscilloscope from the Info menu,
and watch what happens to
the shape of the waveform as you increase the !Volume fader. This clipped
signal is fed into LPF which
filters out all but the lowest frequencies. Try playing sub-fundamental
distortion and adjusting !Volume.
For complex signals, clipping introduces distortion products that are below
the fundamental as well as
above the fundamental of the signal.



Frequency Modulation
The reason that frequency modulation (FM) can be used to synthesize complex
tones is that it, too, is a
nonlinear process and adds extra harmonics where there were none before. In
Kyma, you can use any
Sound as an FM modulator, including samples or the live input. Try playing
Harp FM; this uses a Celtic
harp sample as the modulator on a sine wave oscillator. The higher the
modulation index, the more har-monic
distortion is introduced.