User Manual

Arturia Microbrute User’s Manual 28
Filter
What is a filter?
In general, a filter follows the oscillator and signal modifiers (wave shapers), and alters
the spectral content of the incoming sound. This can involve either removing (filtering
out) or emphasizing (resonating) particular overtones. Filters are very important circuits
whose design contributes greatly to the synthesizer’s overall sound and character.
Filter types on MicroBrute: Low-pass, Band-pass, and High-pass
A filter can operate in various ways or modes. In the MicroBrute the filter can operate
either as a low-pass filter, a band-pass filter, or a high-pass filter.
In low-pass mode, the spectral contents below a given cutoff frequency (set with the
CUTOFF knob) remain unchanged, while harmonics above the cutoff frequency are
attenuated. In other words, it is called low-pass mode because it passes the low
frequencies below the cutoff and reduces the high frequencies above the cutoff. The
correlation of attenuation to frequency determines the filter’s slope, which is measured
in -dB/octave. The Low Pass filter on MicroBrute is called a 12dB per octave filter
because every octave above the cutoff point is reduced by 12dB.
Figure 23
In band-pass mode, the cutoff frequency becomes a band’s center frequency. Sound
within this band remains unchanged, while harmonics below or above the band’s range
are attenuated.
Figure 24