Moog mf105b ユーザーズマニュアル

sound. Some types of filters (like the bass and treble controls on 
your sound system) have subtle, gentle effects on a sound’s timbre. 
Other types of filters have stronger and more dramatic effects, and 
are frequently used as vital elements in the music-making process. 
Strong filters include phasers, flangers, and wah-type resonant 
filters.

   A graph showing what a filter does is called the filter’s frequency 
response. The horizontal axis is frequency. The vertical axis is the 
filter’s gain.  A gain of “1” (unity) means that, at that frequency, the 
output of the filter is just as strong as the input. A gain of less than 
unity means that the filter’s output is attenuated at that frequency, 
while a gain of greater than unity means that the output is actually 
greater than the input. 

   Figure 4 shows examples of the frequency response 
characteristics of two common types of filters: (a) a shelving 
lowpass filter, which passes frequencies without attenuation up to a 
so-called ‘cutoff frequency’, and attenuates the frequencies above 
cutoff; (b) a resonant filter, which emphasizes frequencies around 
the filter’s ‘center frequency’. 
  Both of these filter types are widely used in contemporary music 
performance. Each of them has its own distinct sound, a large part 
of which is directly related to the shape of its frequency response 
graph. A cut-off filter is used at the lowest effected frequency of 
the MF105B.  The remaining seven filters are all resonant filters.
 
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