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NORD MODULAR V3.0
8. Synthesis basics: Subtractive synthesis
As you can see the curve is flat in the low register (which means it neither amplifies nor dampens the fre-
quencies in this part of the spectrum) and then, at a certain point, gradually starts falling. When applied
to the wave above, this filter cuts away some of the high frequency material in the wave, like this:
Amplitude
Amplitude
+
=
Frequency
Frequency
F F F F
I I I I L L L L T T T T E E E E R R R R T T T T Y Y Y Y P P P P E E E E S S S S
There are many types of filters, all with their different characteristics and purposes. We will here discuss
the three most common types of filters:
Lowpass filter
The lowpass filter dampens high frequencies and lets low frequencies pass through unaffected, as in the
example above. It is the most common synthesizer filter, since it can be used to "round off" the sharp
sound of sawtooth waves and pulse waves.
Amplitude
Fc (Cutoff Frequency)
Frequency
Highpass filter
This is the opposite of the lowpass filter. It lets the high frequencies of the sound pass through and cuts
off the low frequencies. This removes "bass" from a sound, without affecting the high end.
Amplitude
Fc (Cutoff Frequency)
Frequency
Page 197
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