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Appendix B Synthesizer Basics 483
Cuto frequency
The cuto frequency, or cuto, determines where the signal is cut o. Simpler synthesizers have
only lowpass lters. If a signal contains frequencies that range from 20 to 4000 Hz and the cuto
frequency is set at 2500 Hz, frequencies above 2500 Hz are ltered. The lowpass lter allows
frequencies below the cuto point of 2500 Hz to pass through unaected.
The gure below shows a sawtooth wave. The lter is open, with cuto set to its maximum value.
In other words, this waveform is unltered.
The gure below shows a sawtooth wave with the lter cuto near a 50% value. This lter setting
results in suppression of the higher frequencies and a rounding of the edges of the sawtooth
waveform, making it resemble a sine wave. This setting makes the sound softer and less “brassy.”
This example illustrates how using a lter to cut away portions of the frequency spectrum alters
the waveform shape, thus changing the timbre of the sound.