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Table Of Contents
68 Chapter 6 Filter
Using the AutoFilter
The following section provides additional information on using the parameters in the
AutoFilter window.
Filter Parameters
The most important parameters are located on the right side of the AutoFilter window.
The Filter Cutoff knob determines the point where the filter kicks in. Higher frequencies
are attenuated, while lower frequencies are allowed to pass through.
The Resonance knob controls how much frequencies around the cutoff frequency are
emphasized. When you turn Resonance up sufficiently, the filter itself begins oscillating
at the cutoff frequency. Self-oscillation begins before you max out the Resonance
parameter, just like the filters on a Minimoog synthesizer. Increasing Resonance causes
the lowpass filter to cut the bottom end, making the signal sound thinner. You can
compensate for this thinness using the Fatness slider.
Both the envelope and LFO parameters are used to dynamically modulate the cutoff
frequency. The Threshold parameter at the upper-left corner of the AutoFilter window
applies to both sections, and analyzes the level of the input signal. If the input signal
level exceeds the Threshold level, the envelope and LFO are retriggered.
Envelope Parameters
When the input signal exceeds the Threshold level, the control signal is triggered at the
minimum value. Over the period of time determined by the Attack parameter, the
signal reaches its maximum level. It then decreases for the period of time defined by
the Decay value, and then stays at a constant level for the duration of the Sustain value.
Once the signal level drops below the Threshold value, it decreases to its minimum
value over the time period determined by the Release parameter. If the input signal
falls below the Threshold level before the control signal has reached the Sustain level,
the Release phase is triggered. You can modulate the peak value of the Envelope
section using the level of the input signal by adjusting the Dynamic parameter. The
Cutoff Mod. slider determines the intensity of the control signal’s effect on the cutoff
frequency.