Operation Manual

SUBTRACTOR SYNTHESIZER
113
D 12 dB Lowpass (LP 12)
This type of lowpass filter is also widely used in analog synthesizers (Oberheim,
early Korg synths etc.). It has a gentler slope (12 dB/Octave), leaving more of the
harmonics in the filtered sound compared to the LP 24 filter.
The darker curve illustrates the roll-off curve of the 12dB Lowpass Filter. The lighter curve in the
middle represents the filter characteristic when the Resonance parameter is raised.
D Bandpass (BP 12)
A bandpass filter cuts both high and low frequencies, while midrange frequencies
are not affected. Each slope in this filter type has a 12 dB/Octave roll-off.
The darker curve illustrates the roll-off curve of the Bandpass Filter. The lighter curve in the middle
represents the filter characteristic when the Resonance parameter is raised.
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 it’s own, a notch filter doesn’t really alter the
timbre in any dramatic way, simply because most frequencies are let through.