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Table Of Contents
366 Chapter 24 Ultrabeat
The names of the individual filters illustrate their function: A lowpass (LP) filter allows
frequencies lower than the cutoff frequency to pass. It removes (cuts) the highs of a
sound, making it darker and less bright.
A highpass (HP) filter allows frequencies higher than the cutoff frequency to pass. The
lows of the sound are cut.
A bandpass (BP) filter allows a frequency band centered around the cutoff frequency to
pass. Frequencies that lie further away (the lows and highs outside the band) are
filtered out. A sound with a lot of mid frequency content results.
The abbreviation BR stands for band rejection filter. In this mode, the area (the
frequency band, to be more exact) around the cutoff frequency is filtered out while
frequencies that lie further away (from the cutoff frequency) are allowed to pass. The
mid frequencies become softer and the low and high frequencies remain unchanged.
Below the filter type buttons, you’ll find two buttons labeled 12 and 24. These allow you
to select the slope of a filter. All of Ultrabeats filter types offer a filter slope of either 12
or 24 dB/octave.
Note: Filters don’t completely remove the parts of the signal that you wish to filter out
and always work with limited precision in the selected band. The steepness or slope is
measured in decibels of damping per octave (dB/oct). Frequencies that are located
close to the cutoff frequency are generally reduced less than those that are farther away
.
The higher the slope value, the more apparent the level difference is between frequencies
that are nearer the Cutoff frequency and those that are further away from it.
The Cut knob determines the cutoff frequency of the filter.
Note: Adjusting the Cutoff frequency can make a sound darker (LP), thinner (HP), more
nasal (BP) or more transparent (BR), dependent on the type of filter chosen.
Cutoff can be modulated by the sources found in the Mod and Via menus. For more
information, see “Modulation on page 373.
Increasing Resonance boosts frequencies that surround the cutoff frequency. Values
range from 0 (no increase) to self-oscillation of the filter at high resonance values.
Resonance can also be modulated by the sources found in the Mod and Via menus.
Note: Self-oscillation is typical of analog filter circuits. It occurs when the filter feeds
back into itself and begins to oscillate at its natural frequency, when high resonance
values are used.