Sequential PRO 3 - Filters

24
Filters
Sequential
Filters
The Pro 3 has three different lters, each of which has its own unique
character:
• low-pass 1 - 4-pole ota is a 4-pole, 24 db-per-octave resonant lter
based on the Sequential Prophet-6 lter. It can self-oscillate (generate a
sine wave) when resonance is set to its maximum.
• low-pass 2 - 4-pole ladder is a classic 4-pole, 24 db-per-octave resonant
transistor ladder lter. It can self-oscillate when resonance is set to its
maximum
• state-variable - 2-pole ota is a 2-pole, 12 db-per-octave lter based on
the Sequential OB-6 lter. It features low-pass, band-pass, high-pass,
and notch operation. The State-Variable lter cannot self-oscillate.
Another characteristic of the State-Variable lter is that increasing the
amount of resonance does not decrease the amount of low-frequencies
(bass). On Low-pass 1 and Low-pass 2, increasing the amount of reso-
nance de-emphasizes low frequencies. The bp and state controls apply
only to the State-Variable lter.
The differences between these lters can be subtle or dramatic, depending
on their individual settings, the amount of lter resonance applied, and
other factors. The function of the lters is to subtract frequencies from
the sound produced by the oscillators, noise generator, and/or external
audio input, thereby changing the overall harmonic content of the synth’s
sound. This change is varied over time using the Filter Envelope to
produce more dynamic timbres.