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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Filters<br />
Filters overview<br />
The purpose of the filter in a subtractive synthesizer is to remove portions of the signal—the<br />
frequency spectrum—sent from the oscillators. After being filtered, a brilliant-sounding sawtooth<br />
wave can become a smooth, warm sound without sharp treble.<br />
The filter sections of most subtractive synthesizers contain two primary controls known as cutoff<br />
frequency—often abbreviated to cutoff—and resonance. Other common filter parameters are<br />
drive and slope. The filter section of most synthesizers can be modulated by envelopes, LFOs, the<br />
keyboard, or other controls such as the modulation wheel.<br />
Filter types<br />
There are several filter types. Each has a different effect on various portions of the frequency<br />
spectrum:<br />
Highpass Band Reject Lowpass<br />
••<br />
Highpass filter: High frequencies are passed; low frequencies are attenuated.<br />
••<br />
Lowpass filter: Low frequencies are passed; high frequencies are attenuated.<br />
••<br />
Bandpass filter: Only frequencies within a frequency band are passed.<br />
••<br />
Band reject filter: Only frequencies within a frequency band are attenuated.<br />
••<br />
Allpass filter: All frequencies in the spectrum are passed, but the phase of the output<br />
is modified.<br />
Appendix B Synthesizer Basics 483