Apple Logic Express 7 - Manual (Page 97)

Chapter 17 ES1 97
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.
ADSR Via Vel
The main envelope generator (ADSR) modulates the cutoff frequency over the duration
of a note. The intensity of this modulation can be set to positive or negative values, and
can respond to velocity information. If you play pianissimo (Velocity = 1), the
modulation will take place as indicated by the lower arrow. If you strike with the
hardest fortissimo (Velocity = 127), the modulation will take place as indicated by the
upper arrow. The blue bar between the arrows shows the dynamics of this modulation.
You can adjust the modulation range and intensity simultaneously by grabbing the bar
and moving both arrows at once. Note that as you do so, they retain their relative
distance from one another.