Waldorf Edition - Manual (Page 72)

Waldorf Edition
User Manual 72 Waldorf
Feedback
A good filter has a built-in feedback feature. This allows you to feed the filtered signal
back into the filter circuitry. As a result the frequency range around the cutoff frequency
will be emphasized. Depending on the settings, the emphasis can be so strong that the
filter itself starts to oscillate. Extreme settings can cause the filter to carry on oscillating,
even when there is no input signal anymore. This behavior is called self-oscillation.
Feedback strength can be adjusted by changing a parameter often called Resonance
(mostly in synthesizers), Quality or Emphasis (in Equalizers), depending on the type of
filter used.
Filter types
There are a number of different filter types. D-Pole features most of them. Many filter
type names indicate the frequency range that passes the filter unchanged. The following
list describes the types available in D-Pole, and what you can do with the Cutoff para-
meter :

Low Pass : All frequencies above the Cutoff frequency are filtered. Turn Cutoff
down to filter high frequencies. The sound sounds increasingly muffled. Turn Cutoff
up to let high frequencies pass through. The sound becomes more brilliant.
 Band Pass : All frequencies below and above the Cutoff frequency are filtered. Turn
Cutoff down to let lower frequencies pass while higher frequencies are filtered. The
sound gets a bulbous character. Turn Cutoff up to let higher frequencies pass while
lower frequencies are filtered. The sound becomes squeaky.
 High Pass : All frequencies below the Cutoff frequency are filtered. Turn Cutoff
down to let lower frequencies pass. The sound becomes fuller. Turn Cutoff up to fil-
ter lower frequencies. The sound becomes thinner.
 Notch : Signal parts near the Cutoff frequency are filtered while signal parts with ot-
her frequencies pass unchanged. This filter’s name originates from the notch that it
creates in the frequency range. Other commonly used names for it are Band Reject
or Band Stop filter. Turn Cutoff down to filter lower frequencies while others pass
through. Turn Cutoff up to filter higher frequencies while others pass through. The
resulting sound resembles a slight Phaser or Flanger effect.
 Resonator : This isn’t really a filter because the signal passes the filter unchanged. It
however creates a feedback at the Cutoff frequency that can be controlled with the
Resonance parameter.