A Generalization of the Biquadratic Parametric Equalizer
An efficient implementation of parametric equalizers is a cascade of biquadratic filter sections. Traditionally, a section operates in one of 3 operating modes offering Low Shelf, Bell Shaped or High Shelf families of responses. In either mode, each section offers 3 user parameters: Boost/cut gain G, corner frequency fc and bandwidth/slope Q. This paper describes the derivation and implementation of a new 4th user parameter, Symmetry, producing a smooth transition between the 3 above mentioned operating modes while retaining the meaning of the 3 conventional user parameters. All degrees of freedom in the bi-quadratic filter blocks are utilized. Therefore an inverse mapping exists, converting arbitrary (e.g. computer generated) biquadratic coefficient sets back into meaningful EQ parameters allowing further human interpretation and adjustment.
Click to purchase paper or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $20 for non-members, $5 for AES members and is free for E-Library subscribers.