4.1.3 Filter
4.1.3.1 What is a filter?
In general, a filter follows the signal generator and signal enhancers, and modifies
the spectral content of the signal or signals. This can involve either attenuating
(filtering out) or emphasizing (resonating) particular overtones and partial, and
these changes can be either static or dynamic. Filters are very important circuits
whose design contributes greatly to the a synthesizer’s sound and character.
4.1.3.2 Filter types: Low-pass, Band-pass, High-pass and Notch
A filter can operate in various ways or modes. These modes are called
transfer
functions
or
spectral responses
. In the MiniBrute the filter can operate either as a
low-pass filter, a band-pass filter, a high-pass filter, or a notch filter.
In
low-pass
mode, the spectral contents below a given
cutoff frequency
(shortened to cutoff) remain unchanged, while partials above the cutoff are
attenuated. The attenuation is a function of the frequency where the higher the
partial frequency, the greater the attenuation. In other words, it is called a low-
pass mode because it passes the low frequencies below the cutoff and reduces
the high frequencies above the cutoff. This correlation of attenuation to frequency
determines the filter’s slope, which is measured in -dB/octave (i.e., the amount of
attenuation applied to a partial with a frequency twice as high as the cutoff).
Arturia MiniBrute User's Manual
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4 General description
