Operation Manual

SUBTRACTOR SYNTHESIZER
114
However, by combining a notch filter with a lowpass filter (using Filter 2 - see page
115 in this chapter), more musically useful filter characteristics can be created.
Such a filter combination can produce soft timbres that still sound “clear”. The ef-
fect is especially noticeable with low resonance (see page 114) settings.
The darker curve illustrates the roll-off curve of the Notch Filter. The lighter curve in the middle
represents the filter characteristic when the Resonance parameter is raised.
Filter 1 Frequency
The Filter Frequency parameter (often referred to as “cutoff”) determines which area
of the frequency spectrum the filter will operate in. For a lowpass filter, the frequency
parameter could be described as governing the “opening” and “closing” of the filter. If
the Filter Freq is set to zero, none or only the very lowest frequencies are heard, if set
to maximum, all frequencies in the waveform are heard. Gradually changing the Filter
Frequency produces the classic synthesizer filter “sweep” sound.
! Note that the Filter Frequency parameter is usually controlled by the Fil-
ter Envelope (see page 116) as well. Changing the Filter Frequency with
the Freq slider may therefore not produce the expected result.
Resonance
The filter resonance parameter is used to set the Filter characteristic, or quality. For
lowpass filters, raising the filter Res value will emphasize the frequencies around the
set filter frequency. This produces a generally thinner sound, but with a sharper, more
pronounced filter frequency “sweep”. The higher the filter Res value, the more reso-
nant the sound becomes until it produces a whistling or ringing sound. If you set a
high value for the Res parameter and then vary the filter frequency, this will produce a
very distinct sweep, with the ringing sound being very evident at certain frequencies.
• For the highpass filter, the Res parameter operates just like for the lowpass filters.
•When you use the Bandpass or Notch filter, the Resonance setting adjusts the
width of the band. When you raise the Resonance, the band where frequencies
are let through (Bandpass), or cut (Notch) will become narrower. Generally, the
Notch filter produces more musical results using low resonance settings.
Filter Keyboard Track (Kbd)
If Filter Keyboard Track is activated, the filter frequency will increase the further up on
the keyboard you play. If a lowpass filter frequency is constant (a Kbd setting of “0”)
this can introduce a certain loss of “sparkle” in a sound the higher up the keyboard
you play, because the harmonics in the sound are progressively being cut. By using a
degree of Filter Keyboard Tracking, this can be compensated for.