third octave filters (elektor)

In the article on the Elektor equaliser (see elsewhere in this issue) it was noted that third octave filters represented a more ideal solution to the problems of room equalisation, but that their complexity meant they were prohibitively expensive to build and use in a system which covered the entire audio spectrum. For this reason they were discarded as a suitable basis for the Elek tor equaliser. Rather than throw out the baby with the bath water however, various less complex arrangements of a third octave filter system were examined in an attempt to find a more financially viable application. The following circuit provides a reasonably acceptable solution.