Moog MP-201 Informations techniques télécharger pdf (Page 10)

ENVELOPE GENERATORS

Now that we have explained the MIDI MuRF’s lters, let’s proceed

with some more denitions to explain the Animation function.

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 - Envelope

An "Envelope Generator" is

a circuit that produces a control

voltage that corresponds to the shape

of a musical sound’s envelope. 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 the volume to shape the start and end of a musical

sound. An Envelope Generator is started by a trigger - a signal used to

start the envelope shape.

In the MIDI MuRF, there are 8 Envelope generators, one for each

lter, that shape the Volume of that Filter’s signal. The shapes of

the Envelopes are all determined by the setting of the ENVELOPE

Control. The timing and sequence of the Envelopes is determined by the

PATTERN selected. To understand that, let’s continue.

SEQUENCERS and PATTERN GENERATION

A Sequencer is used to generate reoccurring rhythmic patterns, often

by triggering sequences of notes in synthesizers or drum machines.

However sequencers can be used for purposes other than triggering

notes - they can be set up to create reoccurring changes of timbre as

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Moog MP-201 Informations techniques Page 10