This section outlines the ES1 filter parameters.
Cutoff slider: Set the cutoff frequency of the lowpass filter.
Resonance slider: Cut or boost the portions of the signal that surround the frequency defined by the Cutoff parameter. Boost can be set so intensively that the filter begins to oscillate by itself (see Drive the ES1 filter to self-oscillate).
Tip: You can simultaneously adjust the cutoff frequency and resonance parameters by dragging vertically (cutoff) or horizontally (resonance) on the word Filter, found in the center of the black circle.
Slope buttons: The lowpass filter offers four different slopes of band rejection above the cutoff frequency. Click one of the buttons to choose a slope (amount of rejection, expressed in decibels (dB) per octave):
24 dB classic: Mimics the behavior of a Moog filter. Increase the Resonance parameter value to reduce the low end of the signal.
24 dB fat: Compensates for the reduction of low frequency content caused by high Resonance values. This resembles the behavior of an Oberheim filter.
12 dB: Provides a soft, smooth sound that is reminiscent of the early Oberheim SEM synthesizer.
18 dB: Resembles the filter sound of the Roland TB-303.
Drive slider: Change the behavior of the Resonance parameter, which eventually distorts the sound of the waveform. Drive is actually an input level control, which allows you to overdrive the filter.
Key slider: Set the effect that keyboard pitch (the note number) has on filter cutoff frequency modulation.
If Key is set to zero, the cutoff frequency does not change, no matter which key you strike. This makes the lower notes sound comparatively brighter than higher notes.
If Key is set to maximum, the filter follows the pitch, resulting in a constant relationship between cutoff frequency and pitch. This mirrors the properties of many acoustic instruments, where higher notes sound both brighter in tone and higher in pitch.
ADSR via Vel sliders: Drag to determine how note velocity affects modulation of the filter cutoff frequency with the envelope generator. See ES1 envelope parameters overview.
Filter Boost button (Extended Parameters area): Increase the output of the filter by approximately 10 decibels. The filter input has a corresponding decrease of approximately 10 decibels, maintaining the overall level. This parameter is particularly useful when applying high Resonance values. See Drive the ES1 filter to self-oscillate.