User`s manual

65
4.4.7: Comb Filter
Application:
The Comb filter is used to remove, or "notch out", harmonically related noises (noises which
have exactly equally-spaced frequency components), such as power-line hum, constant-speed
motor/generator noises, etc., from the input audio. The filter response consists of a series of
equally-spaced notches which resemble a hair comb, hence the name "Comb filter".
Adjust the Comb Frequency to the desired spacing between notches (also known as
"fundamental frequency"). Set the Notch Limit to the frequency beyond which you do not
want any more notches. Set the Notch Depth to the amount in dB by which noise frequency
components are to be reduced.
Normally, the Notch Harmonics option will be set to All, causing frequencies at all multiples
of the Comb Frequency (within the Notch Limit) to be reduced. However, certain types of
noises have only the odd or even harmonic components present. In these situations, set the
Notch Harmonics option to either Odd or Even.
Figure 4-27 Comb Filter Control Window