Phasing Questions?

[angelacoolbreeze]

(1)What is meant when a track or instrument is said to be out of phase? (2)How do you check to see if your mikes are in correct phase?

[Danny M]

[quote]Originally posted by angelacoolbreeze: (1)What is meant when a track or instrument is said to be out of phase?[/quote]This occurs when multiple identical (or, more often, similar) sound/ signal sources arrive at a destination at different times. (It also works for a single source arriving at multiple transducers, and the like.) In practical reality, we might say that a snare drum is being picked up by two microphones that are some distance apart, and that when we sum the signals we get an undesirable result. (Certain frequencies cancelling due to wave interference.) However, phase is not to be regarded as a bad word, and phase manipulation is often used to good effect (like, say, equalizers). If one wants to be picky, whenever you have a source that can be picked up by more than one microphone, you will always have a situation where certain frequenices will be at different phase angles to one another. (The microphones cannot both occupy the same physical position, so there is a time arrival difference, if only slight.) Whether this actually causes something undesirable to happen depends on many factors, such as the distance between the mics, the relative level of the source at each mic, the mic's pickup of the acoustical space, how the signals are summed, etc. [quote](2)How do you check to see if your mikes are in correct phase[/quote]One way is by listening to see if you have a problem outright, and another way is to mute tracks to see if the sound improves. (Some people also try using polarity swapping to see if that produces a better result.) You can also use plug-ins and hardware devices to analyze the phase relationships of signals. -Danny