3.2.9. What is FM?
FM stands for Frequency Modulation. It's similar to the process of adding vibrato to a violin
note: the straight tone of the violin is changed (i.e., modulated) by the vibrato when the
player moves a finger up and down slightly on the string. The motion of the finger is not
heard directly; what is heard is the way the motion of that finger affects the overall sound.
So it is with the FM Drum: The Carrier provides the fundamental tone of the instrument, and
the Modulator affects that tone in a vibrato-like manner. The Modulator itself is never heard
directly; it is only detected in how it affects the Carrier.
Here's a basic experiment that may help illustrate what is happening with the FM Drum.
Before we begin, set the FM Drum knobs like this:
• Mod Pitch and FM Amt fully counter-clockwise (i.e, their minimum settings)
• Decay and Carrier Pitch fully clockwise (i.e, their maximum settings)
• Level knob fully counter-clockwise (all the way down, for safety, for now)
Now follow these steps:
1. Bring up the Level control gradually to a comfortable listening level. You should
hear a pure tone when the pad is played.
2. Turn the Carrier Pitch knob down and up while playing the pad to hear its full
range of frequencies, and then return it to the top of the range.
3. Do the same thing with the Decay knob while playing the pad: turn it all the way
down and back up to hear how that affects the length of the Carrier sound.
4. Very carefully turn the FM Amt (amount) knob up as you play the pad. This allows
the Modulator to affect the Carrier.
5. Bring the FM Amt knob to about the 12:00 position (straight up) so the effect of
the Modulator on the Carrier is not as extreme.
6. Now very carefully turn the Mod Pitch knob. This increases the frequency of the
Modulator, which in turn will modulate the frequency (pitch) of the Carrier. The
character of the overall sound changes dramatically as the value of this knob is
increased.
7. Find an interesting frequency for the Mod Pitch, and then adjust the level of the
FM Amt knob. It has an entirely different effect upon the overall sound, causing
the same frequencies to interact as their ratios change.
8. As a final experiment, leave the FM Amt and Mod Pitch knobs fully clockwise (at
maximum) and then turn the Carrier Pitch knob down and up. This is yet another
very dramatic and interesting way to alter the overall sound: changing the ratio
of the Carrier Pitch and Mod Pitch to one another.
The FM Drum is an extremely versatile instrument, as this experiment has demonstrated.
But it can be altered even more by introducing its Color effect. We'll learn about that next!
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Arturia - User Manual DrumBrute Impact - The Instruments
Summary of Contents for DRUMBRUTE IMPACT
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