Shift Limit; Limit Option - Kurzweil PC88 Musician's Manual

Shift Limit

What happens when you transpose so far that the resulting notes are out of range? ThatÕs
where the Shift Limit parameter comes in. This number determines how far up or down the
Arpeggiator will play from the original note. The minimum value is 0 (which is, admittedly, not
of much use), and the maximum is 88. When the Arpeggiator reaches the limit, one of several
things will happen, as determined by the Limit Opt parameter.

Limit Option

If Limit Opt is set to Stop , then when the Arpeggiator has shifted notes up or down to the limit,
it stops playing. If it is set to Reset , then when it reaches the limit, the Arpeggiator goes back to
its original pitch and starts over again, continuing to transpose as it plays. If the limit allows the
notes to go out of MIDI range (for example, if you set Shift to 12, set the limit to 80, and play
C4), then those ÒghostÓ notes will not sound, but they will take up rhythmic space: the
Arpeggiator will wait for the cycle to play itself out before starting over.
Unipolar means the Arpeggiator will play the last note before it reaches the limit and then start
shifting notes in the opposite direction, using the same interval. When it gets back to its starting
point, it reverses again, and so keeps bouncing back and forth between the original pitch and
the limit, until you pull the plug.
Bipolar starts out the same way as Unipolar, but as the cycle bounces its way back to the
original pitch, it keeps going past the original pitch, and continues to shift until it hits the Shift
Limit in the opposite direction. Then it reverses and heads back to the original pitch, going past
it until it hits the Shift Limit again, and thus bouncing back and forth between the Shift Limit
and its negative counterpart (Òevil twinÓ, if you will) for all of eternity.
Flt Reset adds a little bit of randomness to the process. ÒFltÓ stands for ÒFloatÓ, and it means
that when the Arpeggiator reaches the Shift Limit, it doesnÕt necessarily reset to the original
pitch. Instead, it looks at the Þrst note that would exceed the Shift Limit, and calculates the
interval between it and the Shift Limit. It then starts the cycle over again, but instead of starting
with the Þrst original pitch, it transposes that pitch by the interval it just calculated, and
continues from there. HereÕs a very simple example. The only note in the Arpeggiator cycle is
C3, the Note Shift is 7 (a perfect Þfth), and the Note Limit is 26. The Arpeggiator plays C3, then
G3, then D4, then A4. The next note, E5, would be above the Limit, D5 (26 semitones above C3).
With a normal Reset, the Arpeggiator would start over again at C3. With the Float turned on,
however, the Arpeggiator (clever little devil!) looks at the difference between E5 and D5 Ñ a
whole step Ñ and applies it to the starting note, raising it by a whole step from C3 to D3.
Subsequent notes will then be A3, E4, and B4. Then it will see that the next note Ñ F#5 Ñ
would be a major third above the limit, and so it applies that interval to the starting point Ñ
and you get E3, and the beat goes on.
Flt Unip uses the same concept and applies it to the Unipolar mode: when it reaches the limit,
the Arpeggiator calculates the difference between the next note and the limit, and transposes all
subsequent notes by that interval, even though theyÕre now going in the opposite direction. ÒFlt
BiplÓ does the same thing with the Bipolar mode: after the limit is exceeded in one direction,
notes are transposed by the usual interval, and when the cycle goes back and reaches the
opposite end, another calculation is done, and subsequent notes are transposed according to
that interval Ñ which is going to be in the opposite direction of the Þrst transposing interval,
and not necessarily the same distance.
The Arpeggiator can be a lot of fun, even if you donÕt always understand exactly what itÕs
doing. Keep in mind that the stranger the algorithm you set up, the more unlikely the notes will
stay close to one key, so if you want to create something thatÕs going to sound at all diatonic,
keep it simple.
Musician's Guide
The Arpeggiator
6-5