Topic: Two recordings, inverted phase from one another - how to tell which is correct?

[Brian Skalinder]

I have two recordings from the same night, different sources, and I'm using one to patch the other.  However, the recordings' phase is inverted relative to one another.  I've read some posts that recommend ways to check for which gear is properly in phase by recording a sharp transient, like a clap, or thwacking a pen on a desk or some such.  But I don't have the luxury of doing so with both sets of gear, nor am I necessarily convinced that one of the recording setups is *always* out of phase with the other.  So that doesn't help me much.  Anyway...

How do I tell which recording is properly in phase?

I've tried zooming in on the waveforms on as sharp an attack as I can find.  Theoretically, the properly phased recording should have a pos (+) jump in the waveform as a result of the attack.  The improperly phased recording would have an initial neg (-) jump.  But I'm finding it very difficult to determine exactly when the attack occurs, and therefore whether each recording first jumps (+) or (-) as a result of the attack.

For example, in the attached waveform JPGs, which peak represents the *start* of the attack, and therefore will determine which is properly in phase or not?  I'm not sure which peak to use as my guideline - one of the small peaks early in the waveform which likely represent the beginning of the attack (and if so, which of the small peaks), or the first BIG peak relative to the others.  Any ideas?

[fsulloway]

This may help you.  http://taperssection.com/index.php?topic=49528.0
Does one of the recordings seem to lack bass?

[Brian Skalinder]

This may help you.  http://taperssection.com/index.php?topic=49528.0
Does one of the recordings seem to lack bass?

Yeah, I remember that thread and even went back to re-read, but didn't find a definitive answer to my question - the same one Damon posed in that thread.

Neither recording alone - whether in its original state, or inverted - seems to lack bass.  However, when I mix them together:

<1> with the two recordings apparently visually out of phase wrt one another there's strong bass
<2> with the two recordings apparently visually in phase wrt one another (i.e. I inverted one of the recordings), there's a noticeable lack of bass

The above leads me to believe that though they appear out of phase visually, they're not actually out of phase, after all.

I ran AKG C414B-XLS figure-8s Blumlein for one, Schoeps MK41 roughly DIN the other (thanks, neutrino).  I bet the rear lobe / phase of the figure-8s just makes it look like the two recordings are out of phase with one another, but that they're actually in phase with one another.  If they were truly out of phase with one another, mix <1> above should reveal a lack of limited bass, while mix <2> should have plenty.  But the just the opposite is true, so I suspect they're in phase and my eyes deceive me, and my ears are correct.

[fsulloway]

[ my eyes deceive me, and my ears are correct.

Yes, trust your ears.   

[BobW]

if you have a snare hit on it's own or even a single guitar note pluck, the short rise to positive and slow decaying tail will tell you which is "theorectical" correct phase.
Maybe the AKGs should be 180^ spun for figure of eight ?
They may wire them that way for cross-miking a circle of vocalists....

Maybe the phase was backward to the PA?
Remember, in Mono overall phase is a non-issue.   Internal to the stacks' MF/HF/LF it matters.

(hey, I'm freewheeling here, don't mind me...)