Operation Manual

SUBTRACTOR SYNTHESIZER
192
D Highpass (HP12)
A highpass filter is the opposite of a lowpass filter, cutting out lower frequencies
and letting high frequencies pass. The HP filter slope has a 12 dB/Octave roll-off.
The darker curve illustrates the roll-off curve of the Highpass Filter. The lighter curve in the middle
represents the filter characteristic when the Resonance parameter is raised.
D Notch
A notch filter (or band reject filter) could be described as the opposite of a band-
pass filter. It cuts off frequencies in a narrow midrange band, letting the frequen-
cies below and above through. On its own, a notch filter doesn’t really alter the
timbre in any dramatic way, simply because most frequencies are let through.
However, by combining a notch filter with a lowpass filter (using Filter 2 - see page
193 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 193) 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.