On Room Correction and Equalization of Sound Systems

In this note I discuss some issues in filter design for equalization of sound systems. The emphasis is on rationale, not on experiments, and I will focus on a few common misunderstandings. I will briefly describe the basic concepts used in sound equalization, such as FIR and IIR filters, minimum and linear phase and present basic mathematical facts as well as give a background to the philosophy behind the Dirac Live approach. To limit the length of the text, I assume some basic familiarity with the topics covered. I will however refrain from the popular trend in some engineering periodicals of hiding bad ideas behind complex-looking equations. As already mentioned, the emphasis is on the logic of different approaches to equalization rather than experiments. Logic can be checked by the reader, whereas experiments carried out by others always leave room for doubt concerning experiment conditions. Furthermore, as probability theory teaches us, one lucky experiment shows nothing about the underlying rationale, but the underlying rationale will be much more indicative of future experimental outcomes.