Low-Frequency Modulation

In this example, we are using a sine wave oscillator to modulate (wiggle) the frequency of a triangle wave oscillator. The SineOscillator frequency is set to a very low value, like 5 Hz to 10 Hz, so that it causes a slow wiggle in the TriangleOscillator frequency. The SineOscillator in this situation is referred to as an LFO, or low-frequency oscillator. The sine wave is added to a constant value that determines the center frequency of the TriangleOscillator.

To do:

  • Increase the Modulation Depth fader. Notice that it causes the frequency wiggles to get bigger. This controls the amplitude of the SineOscillator.
  • Increase the Modulation Frequency fader. Notice that it causes the frequency wiggles to get faster. This is sometimes called modulation rate. This controls the frequency of the SineOscillator.
  • Set the Modulation Depth to 0.0 and then move the Center Frequency fader. Notice that the sine oscillator goes up and down in pitch without any modulation.
  • Set the ModDepth and the ModFreq faders to their maximum values. Set the Center Frequency to about 150.0. Notice how, when the output of the FreqAdder goes low, the frequency of the TriOsc is at its lowest.