Creating Simple FM (Frequency Modulation) Instruments: BRASS (French Horn)

If you have not already done so, please read the tutorials, Fm Synthesis, Frequency Modulation, and FM Bell.

Here is the SYD patch for an FM brass sound (french horn). Notice the basic FM configuration (Carrier Operator; Modulator Operator). There is an amplitude envelope with a woodwind configuration attached to the Carrier operator (this is patched to the amplitude parameter of the Carrier). In addition, there is an amplitude enveloped attached to the Modulator which is controlling the MODULATION AMOUNT by changing the amplitude value of the Modulator over time.

The theory here is that the ATTACK of a sound will generate the most complex spectra. For a BRASS sound, the envelope controlling the modulator operator will maximize the MODULATION AMOUNT at the moment of attack and then reduce the MODULATION AMOUNT shortly after. This will produce the characteristic "wah" sound of synthesized brass. The MODULATION AMOUNT will then remain constant through the duration (sustain) of the sound. For the decay, the MODULATION AMOUNT will decrease in the same proportion as the attack.

Figure 1: SYD Patch for an FM Clarinet

Here amplitude envelope for a BRASS SOUND. Notice the shape of the attack which produces the characteristic "wah" sound for synthesized brass:

Figure 2: Envelope for a BRASS sound
Listen to the BRASS sound

Here are the values for the Carrier Operator and Modulator Operator:

Figure 3: Carrier Operator Values

Figure 4: Modulator Operator Values

Figure 5: Carrier Envelope Values
Figure 6: Modulator Envelope Values

Notice how the values of the ATTACKs for each envelope reduces significantly (compare the DECAY values with the
ATTACK values). This gives the characteristic "wah" sound for synthesized brass instruments.

Listen to the FM Brass Sound: FM Brass

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