Moog mf105b ユーザーズマニュアル

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instrument’s tone. You will hear the level of each of the 8 filters 
being turned up and down automatically in sequence by the 
Animation at a tempo determined by the RATE control. Note that 
changing the ENVELOPE control affects the shape that turns the 
filters up and down. The PATTERN rotary switch selects different 
patterns that dictate the sequence that turns the filters up and down 
automatically. The MIX control is used to blend the direct sound of 
your instrument with the effected sound.
8. In the next sections we’ll explain exactly how the Bass MuRF’s 
filters work and what the Animation does. For now, understand the 
controls by experimenting with different settings.
FREQUENCIES and  FILTERS
   Let’s start with some definitions. Please read this section 
carefully, as it will help you to understand the basic ideas behind 
the MF-105B Bass MuRF’s filters. 
   Sound is a vibration of the air. The speed of vibration is called 
the frequency. It is measured in Hertz (Hz). One Hz is one 
vibration per second. We hear vibrations from 20 Hz to 20,000 Hz.    
   Musical sounds generally have many frequency components. 
They’re called harmonics, or overtones, or partials. They are 
what give a sound its characteristic tone color, or timbre.  A graph 
showing the strength of each of a sound’s harmonics is called 
a spectrum. A typical spectrum of a musical sound is shown in 
Figure 3 - Typical spectrum of a musical sound.
Figure 3.
   A filter is a signal-
modifying device that colors 
a sound by emphasizing 
some parts of the audio 
spectrum and attenuating 
(cutting down) other parts. In general, a filter has a ‘quality’ of 
its own which is superimposed on the tone color of the original