Sequential Prophet VS - Page 132

132
PERKEY (#66)
This percussive program ends with a metallic "clink" when keys are released.
Monitoring in stereo reveals subtle voice panning. Tailoring the sustaining
timbre of the sound may be accomplished by changing only one or two
parameters in the oscillator group or mixer envelope.
Keyboard Mode
Normally, this program is in Single keyboard mode, but its Split and Double
mode parameters can be activated by simply selecting either mode. Pressing
Split, we nd that the original program plays between C#3 and top C of the
keyboard, while the linked program (#52 "GASEOSA") covers all keys below
C#3. Pressing Double, the same two programs play simultaneously across the
entire keyboard with no detuning between them.
Oscillator Group
The mixer envelope starts at a root/fourth blend of two complex bell-like
waveforms (#91 and #58), instantly shifting to an equal mix of oscillators C and
D (both at concert pitch), creating the program's percussive attack. If rate 1 is
increased, the initial click becomes a chime.
As the envelope moves from point one to point two, oscillator A dominates
the mix, the seventh harmonic —which dominates waveform #58 (oscillator
C)—quickly fades out. The muting of oscillators C and D can be sped up or
slowed down by varying rate 2. Combining dierent values for rates 1 and 2
can change the nature of the program dramatically.
The envelope quickly reaches its sustain point (#3), increasing the amount of
oscillator D in the Mix. Changing rate 3 has little eect because points 2 and 3
are so close. However, if point 2 is moved, you may want to increase rate 3 for
a smoother shift to the sustain mix.
By changing the waveform used by oscillators A or D, the program's
sustaining timbre changes drastically, without aecting its percussive timbre.
(Remember that oscillator C dominates the 50/50 mix of point 2.)
On release, the instant shift to a mix of oscillators A and B (tuned to concert
pitch and up a fourth respectively) creates a nal "plink" —but only if the note
has not been sustained long enough for the amp envelope to decay to zero.
With the ALTERNATE RELEASE footswitch depressed, all envelope release
rates (#4) are extended, doing away with the program's abrupt ending.
Stepping through the modulation sources and destinations (with Source
Select and Dest Select) shows that the A-C axis is slightly modulated by the
keyboard, so that oscillator A is emphasized at the low end of the keyboard,
and oscillator C is emphasized at the lower end. Meanwhile the B-D axis is
modulated by LFO 1 when key pressure or the mod wheel is applied.
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