Topic: Phase Inversion

[kskreider]

I suck at physics.

Now trhat we have that out of the way, what are the repercussions of mixing two sources that are 'out of phase'? 

I made two recordings the other night of the same band.  Mics on stage at 24/96.  (140>f410>700m running wavelab)  I also had a JB3 plugged in off the board. 

I laid out the resampled/dithered aud and chopped up the board into tracks.  As I began synching the board chunks to the audience in a wavelab montage, I happened to notice that when I zoomed in close where the aud had a peak the board had a valley.  I simply opened up each board chunk, inverted the phase to match the audience recording, and started over.  In the end the mix sounds great. 

Would it have sounded different if I didn't invert the phase?

Lay terms please...

[Patrick]

Now trhat we have that out of the way, what are the repercussions of mixing two sources that are 'out of phase'? 

Your head will literally spin if listening with headphones.

[Chuck]

If you take a recorded section and cloned it, then inverted the phase on one and lined them up correctly, the peaks and valleys would cancel each other out and theoretically there would be no sound when playing that audio. So, it was probably a good idea to invert the phase in your case.

[Chuck]

If you take a recorded section and cloned it, then inverted the phase on one and lined them up correctly, the peaks and valleys would cancel each other out and theoretically there would be no sound when playing that audio. So, it was probably a good idea to invert the phase in your case.

Well, that was what I thought I remebered from physics class, but didn't notice the cancelling effect.  I may be getting curious enough to tamper with making a soundless recordings.  This is just theoretical, right?

What causes two sources to be completely out of phase with one another?

If you try the clone/invert thing , and play it, there may be some residual noise that comes from imperfect alignement of the wav forms. As for why the recordings may have been out of phase from each other. Certain amplifier/pre-amplifier designs use feedback into the circuit to add gain or use an inverted design for the op-amps or transistors. One of the pieces of electronics in the soundboard probably inverted the signal and your recorder didn't. Also, distance from the source can change phase. Sound travels in WAVs from the source. If you are at a one distance away from the source and someone is at a different distance the wavs arrive at different times. So, if you are both recording, the recordings will be a certain amount of phase different from each other.