Design Considerations for a Digital Audio Equalizer

The objective of this thesis is to consider a method for designing a digital audio equalizer. The primary design criteria is minimum audible frequency response error between a digital and a "reference" analog equalizer throughout the entire audio frequency range from 20 Hz to 20 Khz. The first step is to obtain a set of analog filters that suitably represent the reference equalization. From these filters, digital filter coefficients are generated using the bilinear transformation. Then, the digital filters are combined with anti-aliasing and D/A reconstruction filters and a zero-order hold to complete the design. Analysis of methods to minimize frequency axis warping effects on the response of the high frequency filters is presented. The problems associated with realizing a filter with low natural frequency and a very high sample rate is also studied.