A**R（Amp Envelope ADSR）
Amplitude（放大器）在电压控制模拟合成器中经常写成VCA（Voltage Controlled Amplitude）
In most synthesizers, the final stage (before the delay effects) is an amplifier (volume control).
This is almost always modulated with an envelope and creates the volume contour of the individual notes.
It is often known as the "VCA" or Voltage Controlled Amplifier
Envelopes are general-purpose modulators. The typical envelope is divided into 4 stages. Attack, Decay, Sustain, Release---ADSR for short. Manipulating the envelope parameters defines a "path" that is run every time the envelope is triggered, usually by a MIDI note-on event. This path is configured to modulate, or change, another parameter. The most important envelope destination is the amplifier. It is important to note that Attack, Decay, and Release are all amounts of time, but sustain is a level. The envelope starts at zero with a MIDI note-on event and proceeds to full level over the attack time; then it continues to the sustain level over the decay time; it stays at the sustain level until a MIDI note off event is received, at which time the envelope returns to zero over the release time.
Amp Envelope（What section of the synth modulates volume over time?） Modulate=change
Attack：起始 Hold：保持 Decay：衰减 Sustain：持续 Release：释放
Attack time：从Note on到最大值的时间，以时间为单位
Decay time：从最高Level衰减到Sustain Level的时间，以时间为单位
Release Time：Note off后Level衰减到零的时间，以时间为单位
Delay time：Attack前，Note on到Attack上升点的时期
Non-sustaining：All instrumental sounds can be placed in one of two categories: sustaining or non-sustaining. If the instrument gets an initial burst of energy then is left to resonate and decay (striking or plucking) then it is a non-sustaining instrument. If energy is being added to the instrument over the course of a note (blowing, bowing, mechanically vibrating), then it is a sustaining instrument. To emulate non-sustaining instruments, the sustain portion of the amplitude envelope is zero. To emulate sustaining instrumental sounds, the sustain portion of your amplitude envelope is non-zero.
“ Attack ” begins when you press a key. How long it takes for sound to go from e to full volume.
Long attack good for pads. Short attack good for short plucks
Release的调节Pads \ ambiance \ bass \ leads音色都常用
-Begins when you release a key
-Determine how long it takes for volume to go from the current volume to 0 volume
-Good for attacks, ambients, and often in bass and leads too.
-0 release gives abrupt unnatural ending cutoff to a note which is undesirable
Envelope repeat Envelope：持续以Attack - Decay的方式重复作用
Velocity sensitive Envelope：受到力度的影响而改变输出Level