Pitch Effects; Stereo Chorus; Quad Chorus; Chorus - Alesis 4 Reference Manual

Overview of Effects – Chapter 3

Pitch Effects

The Pitch effects alter the pitch of a signal in various ways to produce "layered"
timbres that are more complex than the original signal. Although some of these
effects can sound similar to one another depending on the parameter settings, each is
achieved differently and can be quite dramatic under the right circumstances. Pitch
effects are achieved by splitting the signal into at least two parts, effecting the pitch
of one of the parts, then mixing them back together. This eventual mixing is essential
since the overall sound of the effect is achieved by the actual difference between the
dry, uneffected signal and the effects signal. The various types of Pitch change are:

Stereo Chorus

The Chorus effect is achieved by splitting the signal into three parts with a dry signal
and a separate Detuning section for both left and right channels. When the left
channel is detuned sharp, the right is detuned flat, and vice versa. The detuning is
further effected by being modulated by an LFO (low frequency oscillator) which
causes the detuning to vary. Many variables are available in this scheme: the
Predelay can be varied, the LFO depth can be varied, the LFO speed can be varied,
and a portion of the detuned signal can be fed back to the input to increase the effect.
Finally, the waveform shape of the LFO can be changed from a smooth sinewave, to
a more abrupt squarewave to make the pitch detuning more pronounced.

Quad Chorus

Quad Chorus modulates four delayed signals, each with its phase offset by 90°. Each
of the four signals has a separate Predelay variable, allowing you to change the
"rhythm" of the phasing.

Chorus

This is a mono, less processor-intensive version of the Stereo Chorus effect, used in
the Multi Chain Configurations Chorus->Realroom and Chorus->Dly->Room, the
Double Configuration Realroom+Chorus, and the Dual Mono Configurations
Chorus:Chorus and Chorus:Delay.
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