Equalizer

Equalizer is a 3-band parametric equalizer with a low-shelf, mid-bell and high-shelf.

low gain sets the low-shelf boost/cut.

mid freq sets the frequency of the mid boost/cut.

mid gain sets the mid boost/cut.

high gain sets the high-shelf boost/cut

low_freq sets the frequency of the low-shelf band.

high_freq sets the frequency of the high-shelf band.