Loudspeaker and Room Response Equalization Using Parallel Filters: Comparison of Pole Positioning Strategies

Correspondence should be addressed to Balázs Bank ( b mit.bme.hu) ABSTRACT The dire t design of xed-pole parallel se ond-order lters is a very e e tive way of obtaining equalizers having the desirable logarithmi frequen y resolution for audio appli ations. The frequen y resolution of the parallel lter design is ontrolled dire tly by the hoi e of pole frequen ies, similarly to Kautz lters. This paper reviews and ompares di erent pole positioning strategies, su h as using a predetermined pole set, warped IIR lter based pole positioning, multi-band warping, and ustom warping. In addition, a new te hnique based on the ripple density of the transfer fun tion is proposed. The methods are tested on loudspeaker and room response equalization appli ations. It is shown that a predetermined logarithmi pole set gives a eptable equalization despite its simpli ity, while the most a urate results for a given lter order are obtained by multi-band and ustom warping. The ripple-density based pole positioning presents a useful ompromise between a ura y and design omplexity.

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