Moog mf105b ユーザーズマニュアル

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ENVELOPE GENERATORS
 
     Now that we have explained the Bass MuRF’s filters, let’s 
proceed with some more definitions to explain the Animation 
function of the Bass MuRF.
     The term “Envelope” is used to describe the changes that occur 
to a musical sound, from its start to its end. A musical sound can 
have a rapid onset, like the plucking of a string or the striking 
of a drum. It can also have a gradual onset, like a slowly bowed 
violin. With the term “Envelope”, the shape of the start of a sound 
is called the “Attack”.  The end of a sound can have different 
shapes as well – it can be abrupt, like on an organ, or it can be very 
gradual, fading out like a piano note held down. The shape of the 
end of a musical sound is called “Decay”. Both Attack and Decay 
are time-related, and can be measured in seconds or milliseconds. 
Figure 9 illustrates the components of an envelope. 
Figure 9 - a representation of a Volume Envelope
     An “Envelope 
Generator” is a circuit 
that creates a shape 
that corresponds to the 
changes in a musical 
sound. The signal that 
comes out of an Envelope 
generator is sent to a 
control, such as Volume, 
and is used to automatically turn up and down that control to shape 
the start and end of that musical sound.  An Envelope Generator is 
started by a trigger - a signal used to start the envelope shape. 
     In the Bass MuRF, there are 8 Envelope generators, one for 
each filter, that shape the Volume of that filter’s signal.  The 
shape of the Envelopes are all determined by the setting of 
the ENVELOPE Control.  When the Envelopes are started is 
determined by the PATTERN selected.  To understand that, let’s 
continue.