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97
Modulation Techniques
Sequential
Prophet X User’s Guide
Modulation Techniques
6. With the LFO 3 parameters shown in the main display, press Soft
Button 3 to select the
lfo
dest
menu tab, then select
osc
2
shape
with
Soft Knob 1.
7. Set LFO 3
frequency
to 72 and LFO 3
amount
to 68. Note that these
settings differ from those set for LFO 2/oscillator 2
8. Play some chords. Basic PMW string sound!
To hear what a difference pulse-width modulation makes, remove it by
turning the LFO
amount
parameter for both LFO 2 and LFO 3 to zero.
You can use this technique to add harmonic movement to any of the
oscillator waveshapes, not just the pulse wave. But be aware that if you
set the amount of waveshape modulation too high on the pulse wave, it
will become so narrow that the wave’s sound will disappear!
Modulating the Stereo Filters Independently
Because the Prophet X has stereo filters (in 8-voice mode), you can add
even more movement by using the LFOs (or other sources) to indepen-
dently modulate the left-channel and right-channel filter cutoff. This
produces some interesting stereo filtering effects. We’ll re-use the same
two LFOs in the example below. The mod matrix makes it possible to
route the same source to multiple destinations.
To modulate the left and right channels of the stereo filters:
1. Start with the PWM string sound from the previous example.
2. In the
modulation
section, press the
assign
source
button. Use
s
oft
k
nob
1
to scroll to the first available mod slot.
3. Use
s
oft
k
nob
2
to scroll through the various mod sources and choose
lfo
2.
4. Use
s
oft
k
nob
3
to set the amount to 20.
5. Use
s
oft
k
nob
4
to scroll through the various mod destinations and
choose
cutoff
l.
6.
Now do the same for LFO 3 and the right filter channel: Use
s
oft
k
nob
1
to scroll to the next available mod slot.
7. Use
s
oft
k
nob
2
to scroll through the various mod sources and choose
lfo
3.
8. Use
s
oft
k
nob
3
to set the amount to -20.
9. Use
s
oft
k
nob
4
to scroll through the various mod destinations and
choose
cutoff
r.
10. Hold a chord and notice how the sound moves as the cutoff frequency
changes on the left and right channels of the filter.
11.
Increase the filter
resonance
to make the effect more dramatic.
Creating Sounds Using FM (Frequency Modulation)
Frequency modulation is a technique where the frequency of one oscil-
lator modulates another oscillator, producing complex harmonics. This
is how instruments such as the DX7 produced its sounds. In classic FM
instruments, sine waves were used. But because the mod matrix makes
it possible to route any of the Prophet X sound sources to each other
(including sampled instruments), the sonic possibilities are even greater.
To create sounds using frequency modulation:
1. Recall the Basic Program. (See previous examples if necessary.)
2. In the Mixer, turn up Oscillator 2 to 127.
3. Turn Oscillator 1 level down to 0. (Because we’re going to use it as a
mod source, we don’t actually want to hear it.)
4. In the
oscillators
section, set both oscillators to
sine
.
5. In the
modulation
section, press the
assign
source
button. Use
s
oft
k
nob
1
to scroll to the first available mod slot.
6. Use
s
oft
k
nob
2
to scroll through the various mod sources and choose
osc
1.
7. Use
s
oft
k
nob
4
to scroll through the various mod destinations and
choose
o
sc
2
freq
.
8. Now, repeatedly play a note and listen to what happens while you use
s
oft
k
nob
3
to slowly increase the modulation
amount
to 127. The
sound becomes more gong/bell-like.
Summary of Contents for Prophet X
Page 1: ...Samples Plus Synthesis Hybrid Synthesizer ...
Page 7: ......
