Korg NAUTILUS Series, Руководство по параметрам, Страница: 343 / 961

PROGRAM > MOD-7: Oscillator 5–4: VPM Osc1
333
5–4e: Ring Modulator
Ring modulation adds new frequencies to the audio by
multiplying one input, called the Carrier, by another, the
Modulator.
In general, if the frequencies of the Carrier and Modulator
are harmonically related, these new, added frequencies
create brighter timbres. The brighter the inputs, the more
new frequencies are created, and the greater the effect. Small
amounts of detuning between the Carrier and Modulator
produce more motion and richness in the output.
If the Carrier and Modulator frequencies are not related (by
using lots of detune or frequency offset on one of them, for
instance), the ring modulator creates dissonant, gong-like
tones.
In the MOD-7, Input 1 always acts as the Modulator; it has a
direct path into the ring modulator, which is not affected by
the
Input Level control. Depending on the selected VPM
Oscillator Mode , the Carrier can be either the VPM
Oscillator itself (after all applicable FM and waveshaping),
or Input 2.
When Mode is set to Waveshaper , Input 2 is waveshaped
before entering the ring modulator. There are many
possibilities here, but two simple tables may be particularly
useful:
Inverter1 creates a rectified signal, and Integers
clips the signal to negative values only.
As with FM, ring modulation can produce aliasing–
especially at higher frequencies.
For more information about using the ring modulator,
including hands-on tutorials, see “Ring Modulation” on
page 308.
Crossfade [Dry, 1:99…49:51, AM,
51:49…1:99, Wet]
This crossfades between the dry and ring-modulated signal.
The center value, with equal amounts of wet and dry,
produces AM (Amplitude Modulation). You can modulate
this value in real-time, as described under “Crossfade
Parameter Details,” below
More details on ring modulation
In the most simple case, when both the Carrier and
Modulator are sine waves, ring modulation produces two
new frequencies. These new frequencies are called
sidebands.
One is the “sum,” at the Carrier frequency plus the
Modulator frequency. The other is the “difference,” at the
Carrier frequency
minus the Modulator frequency.
For instance, let’s say that Carrier is a 1,000Hz sine wave,
and the Modulator is a 300Hz sine wave. The two sidebands
would be at 1,300Hz (the sum) and 700Hz (the difference).
Notice that neither of these sidebands has a simple musical
or harmonic relationship to the original tones. This is why
the output can sound like a gong, with clangorous and
dissonant overtones.
If the Modulator’s frequency is higher than that of the
Carrier, the difference sideband is reflected around 0Hz,
with a 180 degree phase shift. For instance, if the Carrier is
at 100Hz and the Modulator is at 400Hz, the difference
sideband would be 300Hz, 180 degrees out of phase.
The effect becomes much more complex when using inputs
other than pure sine waves, since separate sum and
difference tones are created for each component frequency in
each input.
For instance, let’s say that the Carrier now has two sine
waves, at 1000Hz and 2000Hz respectively, and that the
Modulator also has two sine waves, at 300Hz and 600Hz.
The output of the ring modulator would then include eight
different sidebands:
• 1,300Hz (1,000Hz+300Hz)
• 1,600Hz (1,000Hz+600Hz)
• 700Hz (1,000Hz–300Hz)
• 400Hz (1,000Hz–600Hz)
• 2,300Hz (2,000Hz+300Hz)
• 2,600Hz (2,000Hz+600Hz)
• 1700Hz (2,000Hz–300Hz)
• 1400Hz (2,000Hz–600Hz)
–99 –97 –95 –48 –25
+99 +50 +25
High Break: C4 Low Break: D1 Center: G2
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