Commodore 128D - Page 157

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Q
UJ
CO
1
CUTOFF
FREQUENCY
Figure 7-7. Low-pass Filter
Conversely, the high-pass filter allows all the
frequencies above the cutoff frequency to pass
through the chip. All the ones below it are fil
tered out. See Figure 7-8. The pass filter pro
duces tinny, hollow sounds.
Q
III
(/)
I
FREQUENCY
Figure 7-8. High-pass Filter
The band-pass filter allows a range of frequen
cies partially above and below the cutoff fre
quency to pass through the SID chip. All other
frequencies above and below the band sur
rounding the cutoff frequency are filtered out.
See Figure 7-9.
CO
CO
2
o
<
FREQUENCY
Figure 7-9. Band-pass Filter
149
USING C128 MODE—Sound and Music in C128 Mode
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