Help with 'phasing'

[Decrink]

I've seen the term 'phasing' applied to using two mikes together at the same time. I know its not good but could someone help me and tell me what it 'sounds' like? How do you know if you're getting it?

I'm trying to record acoustic guitars and mandolins. I have a stereo preamp with a phase rev button on both sides. I've tested with them on and off but my ears can't hear a lot of difference.

I record to a DAW. How can I tell if the mikes are in or our of phase.
Thanks from another long time musician recording beginner.

 

[Harvey Gerst]

It sounds like a flanger pedal stuck in one position. The sound gets thin in a weird way. Imagine a lot of little notch filters at different frequencies. When someone sings, the voice sounds a little hollow.

To hear the effect of phasing , use two identical mics into your preamp (with one of them phase reversed on the preamp), and set them exactly the same distance from the instrument, right next to each other. With the instrument playing (and the two mics summed to mono), flip the phase back to normal - you should hear an increase in volume.

Flip the phase back to where they cancel again and listen while someone slowly moves that mic closer and further from the instrument. As they move it, you should hear something similar to a flanger - that's comb filtering.

 

[Track Rat]

Also, since you're using a DAW, if you expand out your tracks where you can see the wave forms in detail, when two signals are in phase the peaks and valleys will pretty much line up. If they're the exact opposite of each other (signal one shows the first peak pointing up and signal two shows the same first peak pointing down) the two signals are 180 degrees out of phase with each other.