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NORD MODULAR V3.0
In Nord Modular, some of the filter modules can be switched between 12dB and 24dB modes. For
sounds with high resonance (see below), similar to those in the Roland TB-303, the 12dB setting of the
lowpass filter is useful.
Amplitude
24dB (4-pole)
C C C C
U U U U T T T T O O O O F F F F F F F F F F F F R R R R E E E E Q Q Q Q U U U U E E E E N N N N C C C C Y Y Y Y
The most important parameter for a filter is its cutoff frequency, which is the setting that determines where
in the frequency material it should start cutting. If the cutoff frequency in a low pass filter is set to a very
low value, only the lowest harmonics (the bass) will pass through. If you raise the cutoff all the way up,
all frequencies will be let through, as the figure below illustrates.
Amplitude
Filter Frequency
Changing the cutoff frequency is often referred to as "sweeping the filter". This is probably one of the
most important ways of shaping the timbre of a synthesizer sound. By using an envelope you can for ex-
ample have a high cutoff at the beginning of a sound which is then gradually lowered (the filter "closes"
as the sound decays). This would emulate the way most plucked string sound (piano, guitar etc.) behave;
the amplitude of the harmonics decreases as the sound decays.
K K K K
E E E E Y Y Y Y B B B B O O O O A A A A R R R R D D D D T T T T R R R R A A A A C C C C K K K K I I I I N N N N G G G G
When you play different pitches, the oscillators produce different frequencies. This means that the over-
tones in the waveform appear at different frequencies. The cutoff frequency of the filter however, is fixed.
This means that different overtones will be cut off at different pitches. To be more precise, the further up
the keyboard you play, the muddier the sound will be.
Fc (Cutoff Frequency)
12dB (2-pole)
(KBT)
(KBT)
(KBT)
(KBT)
8. Synthesis basics: Subtractive synthesis
Frequency
Frequency
Page 199
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