opaqueice;205531 Wrote: > 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.
Put simply, there is no system - you fiddle with the sound on the desk until it sounds good to you - no science involved! -- Phil Leigh ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=35708 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
