Kurzweil Forte - Manual (Page 143)

Program Edit Mode
The LFO+ Page
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Maximum Rate
This is the fastest possible rate for the LFO. When its Rate Control is set to ON, or when the
control source assigned to it is at its maximum, the LFO runs at its maximum rate.
Rate Control
Assign any control source in the list to modulate the LFO’s rate between its minimum and
maximum. A continuous control like the Mod Wheel is a natural choice, enabling you to
get just about any rate between minimum and maximum. But you can use a switch control
too, to get just the minimum or maximum with nothing in between. Assigning MPress
(aftertouch) as the rate control for an LFO vibrato gives you an easy way to increase the
vibrato rate in realtime, as you can on many acoustic instruments.
LFO Shape
The shape of the LFO waveform determines the nature of its effect on the signal its
modulating. An easy way to check the effects of the different LFO shapes is to set LFO1 as
the value for the Src1 parameter for Pitch on the DSPMOD page, and set the Depth for
Src1 to 400 cents or so. Then go to the LFO+ page, set the Min and Max rates for LFO1
at 0.00 Hz and 4.00 Hz or so, and set the Rate control to MWheel. Now play your MIDI
controller and you’ll hear the LFO’s rate change when you move its Mod Wheel. Select
different LFO Shapes and check out the effect on the pitch.
LFO Phase
Use this parameter to determine the starting point of the LFO’s cycle. One complete cycle of
the LFO is 360 degrees. 0 degrees phase corresponds to a control signal value of 0, becoming
positive. Each 90-degree increment in the phase represents a quarter-cycle of the LFO.
When an LFO is local, the phase parameter gives you control over the starting point of the
LFO for each note (for example, you could make sure every vibrato started below the pitch
you played instead of at the pitch you played). The LFO’s phase also affects global LFOs,
although it’s often indistinguishable, since global LFOs start running as soon as the program
containing them is selected, even if you don’t play any notes.
About ASRs
ASRs are three-section unipolar envelopes—attack, sustain, and release. The Forte’s ASRs
can be triggered by a programmable control source, and can be delayed. ASR1 is always
a local control. ASR2 is local by default, but becomes global if the Globals parameter on
the COMMON page is set to On. ASRs are frequently used to ramp the depth of pitch or
amplitude in a vibrato or tremolo, enabling delays in those effects.