User Manual

21
Prophet 12 Operation Manual
High-Pass Filter
High-Pass Filter
After each voice’s low-pass lter, the signal passes through a 2-pole,
resonant analog high-pass lter. There is also a control for modulating
the lter cutoff with the keyboard.
Frequency: 0...127—Sets the high-pass lter’s cutoff frequency.
Frequencies below the cutoff are attenuated at a slope of 12 dB per
octave. Frequencies above the cutoff pass through the lter unaffected,
hence the name “high-pass.”
Resonance: 0...127—Emphasizes a narrow band of frequencies around
the cutoff frequency. Normally, the high-pass lter does not self oscil-
late at the maximum resonance setting. However, it may be driven into
self-oscillation by routing DC modulation to resonance to push it beyond
what can be achieved by the Resonance control alone. Be aware, though,
that the signal level of the self-oscillation is signicantly higher than
normal, and will likely cause severe clipping, especially as more voices
are played. That can be mitigated by turning down the voltage controlled
amplier envelope amount and, if used, the VCA VelocityAmount.
Key Amount: 0...127—Sets the amount of modulation from the
keyboard to FreqUency (the lter’s cutoff frequency). A setting of 64 will
step the lter in semitone increments for each note, 32 would be quarter-
tones, and so on.
Note: The high-pass lter does not have a dedicated envelope like
the low-pass does. However, auxiliary envelopes 3 and 4 can be
routed directly to the high-pass lter, and any of the envelopes can
be used to modulate the high-pass using the modulation matrix. See
Modulation on page 32 for more information.