Four Band Parametric EQ
A Parametric Equalizer provides very general and precisely controllable equalization using elementary filter sections such as shelf and peaking equalizer filters.
Parameters:
Peaking Equalizer Parameters for Each of Four Bands, N=1,2,3,4:
Level-N
Gain (dB) at the Center Frequency, giving Boost (Gain>0)
or Cut (Gain<0) at that frequency in Band N
Range: -40 to 20 dB (default 0).
Freq-N
Center Frequency (Hz) of the Boost or Cut in Band N
Range: 10 to 15000 Hz (default 85).
QN
Q of the Boost or Cut in Band N - the
Q is proportional to the narrowness of the Boost or Cut
Range: 0.01 to 100 (default 2).
Shelf Parameters
LS Freq
Low Shelf Frequency: Frequency of the upper limit of the Low Shelf band
Range: 10 to 10000 Hz (default 82.4).
In other terms, the Low-Shelf Boost or Cut extends from frequency zero ("dc") to the Low Shelf Frequency
LS Level
Gain (in dB) of the Low Shelf at frequencies above the Low Shelf Frequency
Range: -40 to 20 dB (default 0).
HS Freq
High Shelf Frequency: Frequency of the lower limit of the High Shelf band
Range: 10 to 10000 Hz (default 880).
In other terms, the High-Shelf Boost or Cut extends from the High-Shelf Frequency to half the audio sampling rate ("Nyquist Limit")
HS Level
Gain (in dB) of the High Shelf at frequencies above the High Shelf Frequency
Range: -40 to 20 dB (default 0).
Mathematical Definition of Shelf Filters
Mathematical Definition of Peaking Equalizer Filters