CHAPTER 21. LIVE AUDIO EFFECT REFERENCE
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Predelay controls the delay time, in milliseconds, before the onset of the rst early re ection.
This delays the reverberation relative to the input signal. One's impression of the size of a
real room depends partly on this delay. Typical values for natural sounds range from 1ms
to 25ms.
21.25.2
Early Re ections
These are the earliest echoes that you hear after they bounce off a room's walls, before
the onset of the diffused reverberation tail.
Their amplitude and distribution give an
impression of the room's character.
The Shape control sculpts the prominence of the early re ections, as well as their overlap
with the diffused sound. With small values, the re ections decay more gradually and the
diffused sound occurs sooner, leading to a larger overlap between these components. With
large values, the re ections decay more rapidly and the diffused onset occurs later. A
higher value can sometimes improve the source's intelligibility, while a lower value may give
a smoother decay.
Spin applies modulation to the early re ections. The X-Y control accesses the depth and
frequency of these modulations. A larger depth tends to provide a less-colored (more
spectrally neutral) late diffusion response. If the modulation frequency is too high, doppler
frequency shifting of the source sound will occur, along with surreal panning effects. Spin
may be turned off, using the associated switch, for modest CPU savings.
21.25.3
Global Settings
The Quality chooser controls the tradeoff between reverb quality and performance. Eco
uses minimal CPU resources, while High delivers the richest reverberation.
The Size parameter controls the room's volume. At one extreme, a very large size will
lend a shifting, diffused delay effect to the reverb. The other extreme a very small value
will give it a highly colored, metallic feel.
The Stereo Image control determines the width of the output's stereo image. At the highest
setting of 120 degrees, each ear receives a reverberant channel that is independent of the
