User Manual

5.1.4. The filter or VCF
The audio signal generated by an oscillator (the waveform) is next generally directed to a
filter module (Voltage Controlled Filter). It is this module that we use to control the sound
by filtering (by subtraction, which explains the name given to this type of synthesis) the
harmonics situated around a cut-off frequency. It can be considered to be a sophisticated
equalizer that reduces, depending on the case, the high or low frequencies of a sound.
5.1.4.1. The cut-off frequency
The removal of undesirable frequencies at the cut-off frequency is not done suddenly but
progressively, depending on the filtering slope. This filtering slope is expressed in decibels
per octave (or dB/Oct). The filters used in classic analog synthesizers have 24 dB/Oct or 12
dB/Oct slopes.
The Mini V offers 1 type of slope: 24 dB/Oct slope.
On the Mini V, you have access to one type of filtering.
The low-pass filter (LPF) progressively removes high frequencies above the assigned
frequency limit (the cut-off frequency) and allows the sound below the cut-off to pass
through unchanged. Depending on the setting we will hear the sound becoming more or
less “brilliant”, more or less “dampened”.
This is the type of filtering that you will find more than often on synthesizers that use
subtractive synthesis. It can be found on most of the recent analog and digital synthesizers.
Spectral representation of a rough then 24dB LP filtered
signal
Spectrum of a noise signal proceed with a low-pass filter
Arturia - User Manual Mini V - THE BASICS OF SUBTRACTIVE SYNTHESIS 64