User Manual

35
Prophet X User’s Guide
Filter
TAB 3 - LP Filter
CUTOFF
Cuto DriveResonance Key>LPF Freq
RESONANCE
0 0 4328
KEY>LPF FREQ
DRIVE
LP FilterVCF ADSR LPF MiscVCF Env Amt
Cutoff: 0...164—Sets the lter’s cutoff frequency. Frequencies are
reduced from the top down, cutting the high frequencies and passing the
low frequencies, hence the name “low-pass.”
Resonance: 0...255—Emphasizes a narrow band of frequencies around
the cutoff frequency. High levels of resonance can cause the lter to self-
oscillate and generate its own pitch.
Drive: 0...127—Increases signal input to the lter, boosting volume and
adding harmonic saturation and warmth.
Key>LPF Freq: 0...127—Sets the amount of modulation from the
keyboard to the lter’s cutoff frequency. Any setting above zero means
that the higher the note played on the keyboard, the more the lter opens.
This is useful for adding brightness to a sound as higher notes are played,
which is typically how acoustic instruments behave. When set to zero,
keyboard lter tracking is off, meaning that lter frequency is unaffected by
playing higher or lower notes on the keyboard. When set to 127, the lter
will track in half-step increments, which can be useful if you are using
the lter to generate a pitch through self-oscillation.
The description of envelope behavior just given is true when the amount param-
eter is set to a positive value. But since this control is actually bipolar, it is possible to
set a negative amount of modulation. In this case, the envelopes are inverted and their
behavior changes. The best way to get a feel for the difference is to experiment with
both positive and negative settings of the env amount parameter.
The cutoff frequency setting may limit the effect of the envelope on the lter. For
example, in low-pass lter mode , if cutoff is at its highest setting, a positive envelope
amount will have no effect on the lter since the lter is already completely open.