Akai MPC Reference Manual page 53

The Filter Envelope Edit section in the display of the MPC hardware
How does an envelope work?
An Envelope creates a variable control signal. It can be used, for instance, to modulate the filter
settings of a sound over a given period of time. The classic Envelope comprises four separately
controllable parameters: Attack, Decay, Sustain and Release, which is why it is also called ADSR
Envelope. Everytime you hit a pad on the MPC, an Envelope is started. Within the period of time
you have defined with the ATTACK (ATK) parameter, it rises to its maximum value. After that it
will enter the decay phase with its duration defined by the DECAY value until it reaches the
sustain level, set by SUSTAIN (SUST) parameter. This level is retained until the pad or key is
released. It is followed by - you've guessed it – the release phase, which is set with the RELEASE
(REL) dial and determines the the time span, the envelope needs to reach its minimum or neutral
level.
PAD PLAY MODES SECTION (Drum Programs only)
Here you can set the behavior for (drum) samples for each pad.
GROUPs. When pads assigned to the same mute group receive MIDI notes, the last note played
will mute any other sounding instrument of that mute group. Use this function to program realistic
hi-hats, especially if only the open or closed hat should be heard.
With LAYER PLAY, you can determine how multiple samples assigned to the same pad are
played. Activate the Cycle (CYC) function to play the next layer's sample each time that pad is
played. In other words, the samples will cycle through the layers as follows: 1, 2, 3, 4, 1, 2, 3, 4...
etc. Use Velocity (VEL) to switch between samples depending on how hard you hit a pad. Finally,
the Random (RAN) function will allow all the samples assigned to the pad to be selected
randomly. This way, every time you hit a pad, one of the assigned samples will be randomly
chosen to play.
With the SAMPLE PLAY function, you can determine whether the pad is played as ONE-SHOT
(from start to end) or defined by NOTE-ON (only as long as the note is held). Select ONE-SHOT
when you want to play short drum sounds. However, if you are using a long sample, it is
sometimes better to set it to NOTE-ON so you can control a sound's duration by pressing and
holding its corresponding pad.
PAD PLAY lets you choose between two options: In MONO mode you can play only one pad at a
time. If you hit a pad while another or the same one is still playing, the new sample(s) will
immediately mute the sample(s) that are playing. In POLY mode you can play several pads at the
same time.
To edit the Pad Play Modes parameters press the F5 button
(Lfo Mod) on your MPC hardware. Use Q-Link knobs Q13 –
Q16 for direct access of all 4 parameters. Keep in mind that
these parameters are available only in DRUM programs.
You can assign the selected pad to one of the 32 available MUTE
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