Dave Smith Instruments Sequential PROPHET X, User Manual, Page: 47 / 172

35 Prophet X User’s Guide Filter
TAB 3 - LP Filter
CUTOFF
Cutoff Drive Resonance Key>LPF Freq
RESONANCE
0 0 43 28
KEY>LPF FREQ DRIVE
LP Filter VCF ADSR LPF Misc VCF Env Amt
Cutoff: 0...164
—Sets the filter’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 filter to self-
oscillate and generate its own pitch.
Drive: 0...127
—Increases signal input to the filter, boosting volume and
adding harmonic saturation and warmth.
Key>LPF Freq: 0...127
—Sets the amount of modulation from the
keyboard to the filter’s cutoff frequency. Any setting above zero means
that the higher the note played on the keyboard, the more the filter 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 filter tracking is off, meaning that filter frequency is unaffected by
playing higher or lower notes on the keyboard. When set to 127, the filter
will track in half-step increments, which can be useful if you are using
the filter 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 filter. For
example, in low-pass filter mode , if
cutoff
is at its highest setting, a positive envelope
amount will have no effect on the filter since the filter is already completely open.