Kurzweil K2661 Musician's Manual page 516

DSP Functions
The DSP Functions
2-Pole Notch Filter:
Width in octaves
The two-pole notch filter has two control-input pages, one for center frequency, one for width.
Partials with frequencies above or below the notch will be unaffected. Within the notch, partials
will be attenuated according to the width of the notch. The width is defined in terms of the
number of octaves between the points on the signal's attenuation curve where the attenuation is
3 dB (see the explanation of F2 WID for the PARAMETRIC EQ function—page 16-26). For
example, if the width is set at four octaves, then the attenuation will be 3 dB at two octaves in
either direction from the center frequency. There's no attenuation of partials at more than two
octaves in either direction from the center frequency.
Two-pole Notch Filter, Fixed Width (NOTCH2)
The only functional difference between NOTCH2 and NOTCH FILTER is that the width of
NOTCH2 is fixed at 2.2 octaves. This gives you a one-stage notch filter function.
16-20
10 100
0
-10
-20
-30
-40
-50
-60
-70
Center frequency
width from .1 to 4 octaves
-80
10 100
0
-10
-20
C 4
-30
-40
-50
-60
Center frequency
at C 4, C 7, C 10
-70
Frequency in Hertz
1000 10000
4
= C 6;
Frequency in Hertz
1000 10000
100000
.1
100000
C 10