15
FM Tone Generation
Essentials for Determining Voices
Voices are determined by the following main elements:
(1) The output level from each operator (OUTPUT LEVEL).
(2) The frequency of the tone put out by each operator
(OUTPUT FREQUENCY).
(3) The feedback level (FEEDBACK LEVEL).
(4) The Envelope Generator (EG).
Each of these will be explained in order.
(1) The output level from each operator
When voices are edited, the most important point is the output level for each operator.
Among these, the output level of the modulator has the largest effect on the voice. For
example, when two operators are vertically combined, and the output level of modulator B
is set to zero, the output waveform of carrier A will be a simple sine wave (a dark tone with
no harmonics included). If the output level of the modulator is gradually increased from
this condition, the amount of modulation will become deeper and the output waveform
from the carrier will change to one with many harmonics in it. As the harmonics increase,
the tone will also become brighter, finally changing to a harsh, grating sound.
From this we can conclude that the degree of modulation, which equals the brightness of
the sound, changes in relation to the output level of the modulator.
Feedback
5
4
6
2
1
3
Algorithm 4
The waveform changes a lot.
A
B
A
B
A
B
Modulator
Output Level = 0
Carrier
Sine wave
The output level is
increased slightly.
The waveform changes
slightly.
The output level is
greatly increased.