This is a question for anyone with any experience with audio recording. I've been thinking about the question of the audibility of polarity inversion (or absolute phase as it's sometimes called - let's define it as the effect of reversing the leads on each of your speakers). I know this can be audible in certain very special circumstances, but I want to know whether there is ever a correct choice of polarity in some sense. In particular, does it make sense to discuss correct polarity when the recording being played back was made with more than one mic per channel and there was more than one source of sound?
Suppose you were making a mono (for simplicity) recording, but were using two mics which you were intending to mix down to one channel. Now if you have only one source of sound, but the mics are not the same distance away from it, you could time-align the recordings and then sum them. In that case there is a sense in which you could preserve the polarity of the original signal.* But now suppose there were two sources of sound at different locations. In that case if a note is struck simultaneously by both sources, I don't see any way to time-align the recordings made by the two mics so that the phase is in any sense accurately recorded for both sources. If you time-align one, the other will not be aligned and will therefore be to some extent out of phase. In a more realistic situation with a stereo recording, many mics, and many direct and reflected sound sources, it seems that there simply isn't any way to define what you would even mean by the "correct" polarity. However it is possibly still true that for recordings made with one mic/channel, and where great care is taken throughout to keep track of the phase, you could have a correct polarity... except that even then, for stereo recordings it seems the speakers in the listening room would have to be placed the same distance apart as the two mics were when recording. If not, the sound arriving at your ears will be out of phase! That makes it seem really hopeless. Any comments? How do recording engineers handle this - do they just adjust phases from different mics until the mix sounds the best to them, or is there some definite system? *I'm going to assume the sound source is a monopole radiator, meaning the leading edge of the wave is either a compression or a rarefaction at all angles. An ideal plucked string is a dipole radiator and does not have this characteristic - the leading edge of the wave will be a rarefaction on one side and a compression on the other - but I want to leave that issue aside for now. -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=35708 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
