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8. FM principles in action
1 In the previous tutorial, we saw how even the oscillators can be used as modulation sources. This freeform routing is a core concept in modular synthesis, and here we’ll use it to create FM – that’s frequency modulation – synthesis sounds. Load the 00 User » Init patch, and set Osc 1’s PD knob to 0, so it’s outputting just a sine wave. Classic FM is based purely on sine waves, so this is a good place to start. 4 The final two options, Rel fine and Rel course, also directly adjust frequency, but instead of adding to the frequency, they multiply it. The same caveat applies regarding symmetrical waveforms. Note that the Lin and Rel modes can create a ‘through-zero’ FM effect, whereby frequency can be modulated into the negative range, causing the waveform to run backwards! See the video for a demo. 2 Connect Osc 2’s Output to Osc 1’s Phase Modulation input – it’s beneath the Phase Modulation knob, adjacent to Phase. Give the Phase Modulation dial a good twirl to hear a range of classic FM timbres. There are a bunch of selectable Phase Modulation modes, with the PM fine, PM medium and PM coarse modes offering increasingly strong modulation of phase. 5 Set Osc 1’s Phase mode back to PM Coarse, increase the knob to full, and disable Osc 2’s Fractalize mode to get us back to standard FM synthesis territory. Now increase Osc 2’s PD knob to transform the modulator waveform into a saw wave – this creates a great squelchy effect, and demonstrates that FM doesn’t have to be just about sine waves. 3 The Lin 100Hz and Lin 1kHz modes allow direct modulation of frequency, as opposed to phase. As the Bazille CM manual warns, the pitch will only remain stable if the modulating waveform is symmetrical. A sine wave is symmetrical, so we’re all good… but turn on Osc 2’s Fractalize – for a non-symmetrical waveform, as shown – and increase it! This effect is best suited to wild FX design. 6 Adjust the Tune control of Oscillator 2 and you’ll hear that some semitone offsets give a sort of dissonant, metallic beating – although this effect is often used to create FM sounds, we can ensure clean, harmonic results by setting Osc 2’s Tune Mode to Overtone. Try a Tune setting of 4 for a solid beefy tone. We can now better appreciate why u-he included such a comprehensive range of tuning modes.