This is an interesting thread, so I may as well add my 2 cents. As some have said, about 50% of recordings are recorded out of absolute polarity. On some recordings, some tracks are in correct phase and some are 180 degrees out of phase. Also, on some tracks instruments can be recorded in opposite polarity to one another; for example, the piano and drums may be in correct phase and the brass instruments could be recorded in the opposite polarity. Add to this the fact that this phenomenon is normally only audible when reproduced over loudspeakers with accurate phase reproduction. Many multi-driver, multi-way speakers are NOT even close to being phase coherent, so that is why the effect is not apparent on some systems. I could be wrong, but to my ears, recordings with correct absolute polarity sound more forward and palpable in the midrange, which can be best heard on vocals and brass instruments. Incorrect polarity recesses the vocal, overemphasizes the treble and truncates the trailing edges of bass notes -- rendering the sound tight and bright, but not right. This view seems to be opposed to what some others have said. An excellent book on the subject for those interested, is Clark Johnsen's "The Wood Effect". Peace!
