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(3)
FM Tone Generation
To distinguish the two operators when they are combined vertically, they are called the
“Carrier” and the “Modulator.”
• Carrier ................. The operator in the lowest position, that produces the actual sound. (Called A
in the previous section.)
• Modulator ............ An operator positioned above another operator, which changes (modulates)
the sound of the next operator down. (Called B in the previous section.)
When there are three or more operators, each operator is classified as a carrier or modula-
tor in the same way.
Carrier and Modulator
(1) When all the operators are combined horizontally, there is no modulator and they are
all carriers. Because there is no modulation, all waveforms generated by the carriers
are sine waves.
(2) When three operators are piled vertically, only the lowest operator is a carrier. The
modulator on the top modulates the lower modulator, and the modulated waveform
from the lower modulator in turn modulates the carrier. The modulation of the carrier
becomes deeper and the sound output has more overtones.
(3) Here there are two carriers and one modulator. The modulator modulates the carrier
immediately below it. The modulated carrier generates sound with overtones. The
other carrier produces a pure sine wave. Finally, the sound from the two carriers is
mixed to form the whole sound.
(4) Here there is one carrier and two modulators. The two modulators each independently
modulate the single carrier. Since the carrier is modulated by the two modulators, it
generates a sound that has more overtones.
(5) Here there are two sets of two operators that have been combined vertically. In each of
them, the modulator modulates the carrier immediately below it, and the carrier gen-
erates a sound that has overtones. Finally, the sound from the two carriers is mixed to
form the whole sound.
“C” Carrier
“M” Modulator
C C C
M
M
C
M
C
C
M M
C
M M
C C
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