12. Synthesis basics: The filter
NORD MODULAR G2 V1.1
Page 208
As you can see the curve is flat in the low register (which means it doesn’t affect this part of the spectrum
at all) 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:
+ =
F
F
F
F
IIIIL
L
L
LT
T
T
TE
E
E
ER
R
R
R
T
T
T
TY
Y
Y
YP
P
P
PE
E
E
ES
S
S
S
There are many types of filters, all with their different purposes. We will here discuss the three most com-
mon ones.
L
L
L
L
O
O
O
OW
W
W
WP
P
P
PA
A
A
AS
S
S
SS
S
S
S
F
F
F
FIIIIL
L
L
LT
T
T
TE
E
E
ER
R
R
R
The Lowpass filter dampens high frequencies and let’s 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.
H
H
H
H
IIIIG
G
G
GH
H
H
HP
P
P
PA
A
A
AS
S
S
SS
S
S
S
F
F
F
FIIIIL
L
L
LT
T
T
TE
E
E
ER
R
R
R
This is the opposite of the lowpass filter. It let’s 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.
