Chorus; Doubling; Slapback; Stereo Flanger - E-Mu XK6Xtreme Keys Owner's Manual

Chorus

Doubling

Slapback

Stereo Flanger

The function of a chorus device is to thicken the sound or to make one
voice sound like many. This effect is usually created by mixing one or more
delayed versions of the signal with the original. The delay times used are
too short to be perceived as an echo, but long enough so that comb filtering
does not occur. In addition, the delay time is varied via a low frequency
oscillator to simulate the random differences which occur when multiple
instruments are playing together. A slight amount of feedback improves the
effect by creating multiple images of the sound as it recirculates again and
again.
All the choruses are true stereo using two separate delay lines controlled by
a single set of controls. The delay times are slightly different for each
channel and the LFO phase is inverted on one channel to help contribute
to the overall chorus effect. The LFO Rate and Depth settings are critical to
achieving a realistic effect, with faster LFO rates generally requiring less LFO
amount and vice-versa.
When a copy of a sound delayed by about 26 milliseconds is added back to
the original, two audio images are perceived by your brain. When the
delayed image is slightly varied or modulated, the illusion of two voices is
created.
Slapback is a single short echo in the range of 50-60 milliseconds. A sound
delayed by this length of time is perceived as a discrete and separate image
which is useful for a thickening effect or as a pre-delay for reverb simulating
a hard, reflective surface such a gymnasium wall.
A flanger consists of a short audio delay line whose output is mixed
together with the original signal. Mixing the delayed and original signals
results in multiple frequency cancellations called a comb filter. Since the
flanger is a type of filter, it works best with harmonically rich sounds.
This is the frequency response of a Comb Filter.
Flanging was originally created using two tape recorders playing identical
recordings. By exactly synchronizing the two decks and then slowing the
speed of one by grasping the tape reel flanges, the flanging effect was born.
Effects
General Effect Descriptions
XK-6 Owners Manual 185