Kurzweil Forte - Manual (Page 174)

Program Edit Mode
Editing VAST Programs With KVA Oscillators
7-77
Examples of Simple DSP Control and Modulation:
Select the Program 998 Editor Template and press the EDIT soft button. Go to the
KEYMAP page and set Keymap to 999 Silence. Next, go to the AMPENV page and set
the mode to User, set Att1 time to .002 and Rel1 time to 0.02 (this gives you basic control
of attack and release envelopes with sliders C and D). Press the ALG soft button and select
Algorithm 8. Select the leftmost empty function block and use the alpha wheel to scroll to
the PWM oscillator. Play some notes to hear the sound of the PWM oscillator.
Select the rightmost empty function block and use the alpha wheel to scroll to the LOPASS
block. You should immediately hear a difference in the sound of the program, because the
LOPASS function is set by default to cut some of the high frequencies from any signal
that passes through it, in this case the PWM signal is passing through. With the LOPASS
function still selected, press the Favorites 1 button. This brings you to the main parameter
for the LOPASS object on the DSPCTL page, which is LP Frq (you can also reach this page
using the DSPCTL soft button). Here you can adjust the initial value of the function, in this
case it is cut off frequency for the low pass filter. For this example, leave this initial value set
to its default. With the LP Frq parameter selected, press right on the cursor button to get to
this function’s sub page (the right half of the display). Select the Veltrk parameter and use
the alpha wheel or alpha numeric pad to turn it all the way up to 10800ct. Now keyboard
velocities will affect the LP Frq parameter. A velocity of 127 will cause the filter’s cut off
frequency to move up 10800 cents from its initial value, a velocity of 0 will have no effect on
the cut off frequency, and values in between will increase the cut off frequency by a scaling
between 0 and 10800 cents. Overall, this will cause higher played velocities to increase the
cut off frequency, making the oscillator sound brighter, and lower velocities to lower the cut
off frequency, making the oscillator sound duller. This method can be used to control any
DSP function that is loaded into an algorithm. See Common DSP Control Parameters for
other control parameters available on the DSPCTL page.
Alternatively, you could assign cut off frequency to be controlled by any continuous
controller, such as the Mod Wheel. Start again with the unedited Program 998 Editor
Template. Follow the same steps as above, but instead of changing any parameters on the
DSPCTL page, press the DSPMOD soft button to reach the DSP Modulation page. On
the left side of the screen, choose the parameter for LP Frq, and then press the right cursor
button to reach the LP Frq sub page. On this sub page, you can assign any continuous
controller to control the cut off frequency of the LOPASS function (or the main parameter
for any function loaded in the current algorithm). Select the Src1 parameter, hold the Enter
button and move the Mod Wheel to quickly select MWheel (the Mod Wheel) as your
control source. Next, press the cursor down button to select the Depth parameter, then use
the alpha wheel or alpha numeric pad to turn it all the way up to 10800ct. Now the Mod
Wheel will affect the LP Frq parameter. Moving the Mod Wheel all the way up (a value of
127) will cause the filter’s cut off frequency to move up 10800 cents from its initial value,
moving the Mod Wheel all the way down (a value of 0) will have no effect on the cut off
frequency, and values in between will increase the cut off frequency by a scaling between 0
and 10800 cents. Now you have the same control over cut off frequency as you did in the
previous example, but now it is controlled by the Mod Wheel. Overall, moving the Mod