Apple Logic Express 7 - Manual (Page 62)

62 Chapter 9 Reverb
Predelay
Predelay is the amount of time that elapses between the original signal, and the arrival
of the early reflections. In any given room size and shape, Predelay determines the
distance between the listener and the walls, ceiling, and floor. When used with
artificially generated reverb, it has proven advantageous to allow this parameter to be
manipulated separately from, and over a greater range than, what is considered natural
for Predelay. In practice, too short a Predelay tends to make it difficult to pinpoint the
position of the signal. It can also color the sound of the original signal. On the other
hand, too long a Predelay can be perceived as an unnatural echo. It can also divorce
the original signal from its early reflections, which leaves an audible gap. The ideal
Predelay setting depends on the properties or, more accurately, the envelope of the
original signal. Percussive signals generally require shorter Predelays than signals where
the attack fades in gradually. A good practice is to use the longest Predelay possible
before undesirable side effects, such as an audible echo, begin materializing.
Room Shape
Use this slider to define the geometric form of the room. The numeric value (3 to 7)
represents the number of corners it has.
Room Size
Unsurprisingly, Room Size determines the dimensions of the room. The numeric value
indicates the length of its walls—the distance between two corners.
Stereo Base
The Stereo Base parameter enables you to define the distance between the two virtual
microphones that you are using to audition the simulated room. Spacing the
microphones slightly further apart than the distance between two human ears
generally delivers the best results. Of course, more realistic results can be obtained if
you choose to use the distance between two ears located on opposite sides of the
same head.
Reverb
This section generates diffuse reverberation.
Initial Delay
This is the delay between the original signal and the diffuse reverb tail. If you’re going
for a natural-sounding, harmonic reverb, the transition between the early reflections
and the reverb tail should be as smooth and seamless as possible. Basically, what we
said about the Predelay holds true for this parameter:
Set the Initial Delay so that it is as long as possible without a perceptible gap between
the early reflections and the reverb tail.