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CHAPTER 18: Sound System Equalization > BIBLIOGRAPHY - Pg. 551

CHAPTER 18 Sound System Equalization microphone you picked up was correctly poled. Holding it in one hand and the second microphone in the other hand, and bringing them closer and closer together while talking into them (such as "one- one-one"). They were in polarity if the apparent bass response increased as they were brought closer together in front of your mouth. They were out of polarity if the bass weakened as they were brought together. In one memorable case the "first" microphone was reversed and this simple process reversed all the others. The arrival on the scene of a polarity checker revealed the error. In any case, be sure to check this important factor before equalizing. A polarity reverser is invaluable in this work. Today we know to check for absolute polarity as it has been repeatedly demonstrated that it is audible on speech. TEF analyzer phase measurements instantly indicate the correct polarity (as well as, in the TEF case, the difference between polarity and phase). Be careful before you rewire microphones; the patch cords could be miswired. LOUDSPEAKER POLARITY In examining the "raw" response of a loudspeaker array, pick the poling that gives the most usable response through the crossover region. True phasing can enter in here, as well as polarity, and great care should be exercised in the relative positioning of horns to each other, especially the spacing and posi- tioning of the high-frequency elements in relation to the low-frequency elements. Remember, out in the audience area there will be phase relationships between direct and reflected sound as well as those between two direct sound sources. The real-time analyzer is invaluable for examining the potential vari- ations and their effects on the audience area. Today, through TEF analysis we have identified signal mis- alignments of from fractions of an inch to about one foot as particularly hazardous to speech quality.