E-Mu XL-7 Command Station, Owner'S Manual

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XL-7 Owners Manual 191
Programming Basics
Dynamic Filters
A filter which only lets a certain band of frequencies pass is called a
band-pass filter .
A notch filter is just the opposite of a band-pass filter and is used to
eliminate a narrow band of frequencies.
Another control found on traditional filters is called Q or resonance. A
lowpass filter with a high Q emphasizes the frequencies around the cutoff
frequency. The following chart shows how different amounts of Q affect
the low-pass filter response. In terms of sound, frequencies around the
cutoff tend to “ring” or resonate with high Q settings. If a filter with high Q
is slowly swept back and forth, various overtones are “picked out” of the
sound and amplified as the resonant peak sweeps over them. Bells and
gongs are real world examples of sounds which have a high Q.
20
40
60
80
100
40 80 160 360 720 1440 2880
Frequency
...
Amplitude
Center Frequency
Filter
Output
Band Pass
Filter
Frequency
Amplitude
Low Q Med Q High Q