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Table Of Contents
Chapter 20 ES2 217
 The abbreviation BP stands for bandpass. In this mode, only the frequency band
directly surrounding the cutoff frequency can pass. All other frequencies are cut. The
Resonance parameter controls the width of the frequency band that can pass. The
bandpass filter is a two-pole filter with a slope of 6 dB/octave on each side of the
band.
Filter 2 FM
The cutoff frequency of Filter 2 can be modulated by the sine wave of Oscillator 1,
which means that it can be modulated in the audio frequency range.
The effect of such filter modulations in the audio spectrum is unpredictable, but the
results tend to remain harmonic as long as the modulation intensity doesn’t get too
high. FM defines the intensity of frequency modulation. This parameter can be
modulated in real-time: In the Router, this modulation is abbreviated as LPF FM.
A clean sine wave, at the frequency of Oscillator 1, is always used as the modulation
source.
Note: Don’t confuse this type of filter frequency modulation with the FM feature of
Oscillator 1, which can be modulated by Oscillator 2, as described in the “Linear
Frequency Modulation” section, on page 205. If a frequency modulation of Oscillator 1
by Oscillator 2 is used, it does not influence the (sine wave) signal used to modulate
the cutoff frequencies.
Filter 2 can be driven to self-oscillation. If you set a very high value for Resonance, it will
produce a sine wave. This self-oscillating sine wave will distort at the maximum
Resonance value. If you mute all oscillators, you’ll only hear this sine oscillation. By
modulating the Cutoff Frequency, you can produce effects similar to those produced
by modulating the frequency of Oscillator 1 with Oscillator 2.