Apple MainStage 3 Instruments - MainStage 3 Instruments
Apple MainStage 3 Instruments - MainStage 3 Instruments
Apple MainStage 3 Instruments - MainStage 3 Instruments
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Use Ultrabeat oscillator 1 FM mode<br />
FM (frequency modulation) synthesis is well suited for creating bell-like digital tones and metallic<br />
sounds. The principle of frequency modulation (FM) synthesis was developed in the late 1960s<br />
and early 1970s by John Chowning. It was popularized by Yamaha’s range of DX synthesizers in<br />
the 1980s. Although Ultrabeat can’t be compared with the DX series in the discipline of pure<br />
FM synthesis, it can achieve some of the signature sounds of these instruments.<br />
In pure FM synthesis, the frequency of one signal generator, or oscillator, is altered (modulated)<br />
by another signal generator. Positive values from the second generator increase the frequency of<br />
the first generator. Negative values decrease the frequency.<br />
In a synthesizer, this type of modulation takes place in the audible range. Depending on the<br />
design of the instrument, you can hear the signals of either the first oscillator alone (being<br />
modulated by the other oscillator), or both oscillators. The interaction between the two<br />
generators alters the waveform signal of the first oscillator and introduces a number of new<br />
harmonics. This harmonic spectrum can then be used as the source signal for further sound<br />
processing, such as filtering, envelope control, and so on. See Frequency modulation (FM)<br />
synthesis on page 493.<br />
In Ultrabeat’s FM synthesis mode, oscillator 1 (the carrier) generates a sine wave. The frequency<br />
of oscillator 1’s sine wave is modulated by the waveform of oscillator 2 (the modulator).<br />
••<br />
When oscillator 2 outputs a positive (or higher) frequency signal, the frequency of<br />
oscillator 1 increases.<br />
••<br />
When oscillator 2 outputs a negative (or lower) frequency signal, the frequency of<br />
oscillator 1 decreases.<br />
The net effect of speeding up or slowing down the frequency of oscillator 1 in each waveform<br />
cycle is a distortion of the basic wave shape. This waveform distortion also introduces a number<br />
of new, audible, harmonics. The more complex the oscillator 2 waveform, the more partials are<br />
created by increasing FM Amount. Watch the display to see how the sine wave takes on an<br />
increasingly complex shape.<br />
Important: The impact of any frequency modulations depends on both the frequency ratio and<br />
the modulation intensity of the two oscillators.<br />
Set the frequency ratio and adjust the modulation intensity<br />
1 Turn on FM mode for oscillator 1.<br />
2 Turn on oscillator 2.<br />
3 Adjust the Pitch parameter values of one, or both, oscillators.<br />
4 Adjust the amount (intensity) of frequency modulation with the FM Amount knob.<br />
FM Amount knob<br />
FM Amount can be modulated by the sources shown in the mod and via pop-up menus. See<br />
Ultrabeat modulation overview on page 360.<br />
Chapter 14 Ultrabeat 342