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FM Tone Generation
On the other hand, because the carrier actually makes the sound, changing the output level
causes a change in the strength (volume) of the sound. If there is only one carrier, this will
simply cause the overall volume to change. However, if there are multiple carriers in the
algorithm, the timbre may also be changed as the balance in volume between the different
carriers is changed.
To summarize these points:
• The voice changes according to the output level of the modulators.
• The volume changes according to the output level of the carriers. The voice may also be changed
as the balance in volume between multiple carriers changes.
(2) The Frequency of the Tone Output from Each Operator
The type of harmonics added to the carrier output by means of the modulator is determined
by the ratio between the frequencies of the modulator and carrier. For example, when two
operators are combined vertically, and "F COARSE" for both of them is set to 1.00, the
frequency ratio will be 1:1 and the first, second, third and following whole number series
harmonics will be generated in order. This type of harmonic configuration is called a
sawtooth wave, and is used for making voices like brass, strings, or piano.
If the "F COARSE" for the modulation in this situation is changed to 2.00, the frequency
ratio will be 1:2, and the odd numbered harmonics, the first, third and fifth and following
harmonics will be generated. This harmonic configuration is called a rectangular wave,
and is used for creating voices for woodwinds like the clarinet and oboe.
Furthermore, if "F FINE" is used so that the frequency ratio is not a whole number, many
non-integer overtones will be produced. The sound can be used for creating metallic sounds,
the noise when strings are hit with something, or breath noise.
16
Modulator
B
Frequency
ratio 1:1
Carrier
A
Sawtooth wave
B
Frequency
ratio 1:2
A
Rectangular wave
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