Kurzweil K2661 Musician's Manual page 500

DSP Functions
Introduction to Algorithm Programming
Key Track Start (KStart)
This parameter appears on many control-input pages, and gives you added control over the
effect of key tracking. For each note you play, it multiplies the value of the KeyTrk parameter by
a number that varies with the note's MIDI key number. If KeyTrk is set to 0, this parameter will
have no effect. When KeyTrk is a nonzero value, KStart will modify the normal key tracking
curve, which is shown is the diagram below. The effect of normal key tracking reaches its
minimum at C -1, and its maximum at C 9. You can use KStart to dampen the effects of key
tracking at one end of the keyboard. If key tracking causes a sound to clip or distort toward the
high end of the keyboard, for example, you can use KStart to reduce the effect of the key
tracking at the upper end without changing its effect on the lower end. To do this you would set
a negative value for KeyTrk, and a unipolar value for KStart.
Unipolar Keystart
The range of values for KStart is C 1 to C 9 unipolar, and C -1 to C 9 bipolar. Unipolar and
bipolar values have different effects on the key tracking. The next three diagrams illustrate the
effect of three different unipolar keystart values on the key tracking curve when a positive value
is assigned for the KeyTrk parameter. At a KStart value of C 4, for example, there is no key
tracking effect below Middle C (it multiplies the key tracking amount by a key number value
of 0). The key tracking value is multiplied by 0 at C 4 (normal key tracking), by 1 at C
D 4, and so on to a maximum of 64 at 5 1/3 octaves above the KStart value. For higher notes, the
key tracking effect would still increase on its own, but the effect of keystart would not increase
further. At a KStart value of C 3, the key tracking value would be multiplied by 0 for C 3 and all
notes below, by 1 for C
before reaching C 9. When KStart is set above C 4, its effect on key tracking will continue to
increase up to C 9, but will not reach full scale at C 9.
You'll use unipolar values for KStart when you want to cancel the key tracking effect on a DSP
function over a sizable portion of the keyboard, but have it increase or decrease throughout the
rest of the keyboard's range. Set high unipolar values for KStart when you want to remove key
tracking from the lower notes, applying it only to the higher notes. If you have set a positive
value for KeyTrk, set low unipolar values when you want to apply key tracking to the lower
notes and pin it at its maximum throughout the upper range of the keyboard. You may want to
use low values of key tracking in this case, depending on the DSP function you're applying.
When the value of the KeyTrk parameter is negative, remember that the key tracking is at its
minimum effect at C 9, and maximum at C -1. In this case, the key tracking effect will be reduced
for notes above the KStart setting. For notes below the keystart note, the normal key tracking
amount will apply.
16-4
C 3 C 4 C 5
#
3, and so on. The key number value would reach its maximum of 64
Normal KeyTrk curve
(Positive KeyTrk value)
#
4, by 2 at