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Table Of Contents
Chapter 19 ES1 189
Filter Parameters
This section outlines the filter parameters available to the ES1.
Drive
This is an input level control for the lowpass filter, which allows you to overdrive the
filter. Its use changes the behavior of the Resonance parameter, and the waveform may
sound distorted.
Cutoff and Resonance
The Cutoff parameter controls the cutoff frequency of the ES1’s lowpass filter.
Resonance emphasizes the portions of the signal which surround the frequency
defined by the Cutoff parameter. This emphasis can be set so intensively, that the filter
begins to oscillate by itself. When driven to self-oscillation, the filter outputs a sine
oscillation (a sine wave). If key is set to 1, you can play the filter chromatically from a
MIDI keyboard.
There is another way to set the cutoff frequency: Click-hold on the word Filter
(surrounded by the slope selectors), and move the mouse vertically to adjust the cutoff
frequency. Moving the mouse horizontally adjusts the resonance.
Slope Buttons
The lowpass filter offers four different slopes of band rejection above the cutoff
frequency.
 The 24 dB classic setting mimics the behavior of a Moog-style filter: turning up the
resonance results in a reduction of the low-end of the signal.
 The 24 dB fat setting compensates for this reduction in low frequency content.
Turning up resonance doesn’t diminish the low-end of the signal, and thus resembles
an Oberheim-style filter.
 18 dB tends to resemble the filter sound of Roland’s TB-303.
 The 12 dB setting provides a soft, smooth sound which is reminiscent of the early
Oberheim SEM.
Key
This parameter controls the amount of cutoff frequency modulation by the keyboard
pitch (note number). If Key is set to zero, the cutoff frequency won’t change, no matter
which key you strike. This makes the lower notes sound relatively brighter than the
higher ones. If Key is set to maximum, the filter follows the pitch, resulting in a constant
relationship between cutoff frequency and pitch.