Crossfading Zones - Kurzweil PC88 A Step By Step Manual

PC88 Made Easy

7. Crossfading Zones

A nice musical effect is to be able to smoothly fade from one sound into another. You
can easily do this with a single slider (or other continuous controller).
1. Follow tutorial #1 to create a 2 zone, layered Setup. To best demonstrate the
crossfade effect, you should pick two sustaining sounds for the two zones, such as
strings and organ, or two different sounding organs. If you have the VGM board in your
unit, try using two similar orchestral sounds, like Oboe and English Horn, or Recorder
and Pan Flute.
2. Hold the Controllers button and move Slider A. If the display is not on zone 1, press
the Zone 1 button. The display now shows Zone:1 Slider A, Ctrl Num:None. Press 7,
then Enter to assign Slider A to Volume.
3. Press the >> button once. Notice that Scale is set to 100%. Press >> again. Notice that
Offset is set to 0. Press >> again. Set the Curve to Sin+.
4. Press the Zone 2 button. Press the << button three times so that you are back to the
Ctrl Num parameter. Set this zone to Volume, just like zone 1.
5. Press the >> button. Press the +/ - button, then 100, then Enter to set the Scale to -
100%.
6. Press the >> button. Set the Offset to 127.
7. Press the >> button. Set the Curve to Cos+. Hold some notes on the keyboard the
keyboard and move the slider up and down. You should hear one sound fading into the
other.
8. Name and save your Setup.
OK, so what is happening? Zone 1 works like normal - moving the slider up sends
volume values from 0 up to 127. But in zone 2, the slider starts off at 127 (because of
the offset) and then decreases in value to 0 as you move the slider up (because of the
negative 100 percent scale).
What about the curve parameters? They change what values are sent as you move the
slider from the very bottom to the very top. With a Linear Curve (essentially no curve),
the values change in even spacing as you move the slider up. With a Sine+ Curve, the
values are spaced close together when you first start to move the slider up, then are
gradually spaced farther apart after the halfway point. A Cosine+ Curve works the
opposite - the values change slowly when you start moving the slider and then change
faster after you reach the midpoint.
So why not use a Linear Curve in the crossfade? It is beyond the scope of this tutorial to
detail dB issues involved when you layer sounds, or to cover how instruments respond
to MIDI volume in dB terms. The bottom line is that if you use Linear curves, the total
amount of amplitude for both zones will be less when the slider is halfway than when it
is all the way up or down. By setting zone 1 to Sine+ and zone 2 to Cosine+, you will
have a smoother volume transition and the amplitude at the midpoint will be about the