EDIT PAGE – Oscillator Frequency Modulation

 

 

FM stands for Frequency Modulation.  FM has been a feature on synthesizers since the 1960s, but it was most famously realized in Yamaha’s DX/TX series of digital synthesizers in the 1980s.  It was well known for producing glassy, metallic sounds and for creating sound that are more harmonically complex.

FM is a form of audio synthesis where the timbre of one waveform, called the “carrier”, is changed by modulating it with the frequency of another waveform, called the “modulator” – hence Frequency Modulation synthesis. 

FM can take simple waveforms, like sine waves, and make them sound quite complex.  In Omnisphere, the exciting thing is that any Soundsource or DSP waveform in Omnisphere can be modulated with FM.

Each Layer in Omnisphere has a dedicated, hidden FM oscillator, which acts as the modulator; so the other Layer’s Oscillator is not required for FM synthesis to work.  This dedicated Modulation Oscillator can utilize different waveforms and both its frequency and depth can be shifted and modulated.

 

FM POWER SWITCH

Turns the FM modulating oscillator on or off.

 

FM KEYBOARD TRACKING

The small music-keyboard switch enables or disables Keyboard Tracking.   The Keyboard Tracking button determines whether the modulator oscillator tracks the keyboard.

If the Keyboard Tracking is turned on, then the modulator oscillator will track the keyboard, meaning it will change pitch with the keyboard.  If Keyboard Tracking is off, the modulation oscillator will not change pitch with the keyboard, it will stay the same pitch no matter what key is played.  This can be useful for more clangorous sounds.

 

FM FREQUENCY

Controls the frequency of the modulator oscillator.  Because the modulator is unheard, it does not change the pitch of the original Oscillator.  Instead it alters the timbral characteristics of the Oscillator’s waveform.

When this horizontal slider is set to just above the minimum, it can produce LFO-type pitch effects.  Moving the slider towards the maximum increases the frequency and begins to oscillate fast enough that it will introduce timbre changes.

The notches along the FREQUENCY slider are markers for the frequency ratios that will produce the most musically useful results. 

These musically useful values at the notches are decimal versions of these ratios - 1/4, 1/2, 3/4 and 1 – represented as .250, .500. .750 and 1.00.

Range 0.000 to 1.000

 

FM DEPTH

Controls the modulator’s depth.  The higher the DEPTH slider is set, the more the dedicated modulator is affecting the timbre of the OSCILLATOR.

Range 0.000 to 1.000

 

FM WAVEFORM

Many FM synthesizers use only Sine waves, but Omnisphere’s modulator can use any one of four different waveforms.  The four mode switches are for Sine, Triangle, Sawtooth and Noise.  Each successive waveform has more overtones and so will add a brighter timbre.

In general FM works better when beginning with a simpler, more pure sound than a sound with a lot of complexity to start with.