Out Of Phase - Can some explain what effect it has on sound?

what is telling you that something is out of phase?

The problems with phase become more apparent when there is more than one microphone involved in recording the same sound. I see you are a guitarist so a great example here would be recording your guitar cab with two mikes. Say one in close and the other further away.

If you are going to mix the two mikes during the mixdown then combining them can cause either the sound to get better or get worse in some cases. (Technical stuff for the moment: the waveform will hit the two mikes at different parts of the cycle at different frequencies)

So altering the phase of one of the mikes will cause the sound to change, for better or worse. Use your ears to judge. For a single vocal track recorded with one microphone changing the phase of that track will have no effect. Because there is nothing for that to react to.

With regard to stereo monitors, if you change the phase of one speaker compared to the other the bass end tends to diminish and also the centre image tends to sound a bit vague.

It becomes important recording bass players too. If a DI is used and a cab mike is used then the phase of one of those signals may need to be altered for the better bass sound. The signals will either add or subtract to create either a strong bottom end or a weak bottom end.

With regard to creating special effects you could also record vocals and guitar etc with two mikes with the two mikes at different distances as mentioned and pan those tracks hard left and right. When the signals are in phase the stereo effect will be there but stronger. If you flip the phase of one of the microphones then the stereo image will still be present but different and it may appear to extend out a bit past the speakers. (Little bit vague in the centre which can be useful) It can be used with stereo effects to produce quite powerful effects as well.

"Heroes" by Bowie MAY have been the song I read about. Although this says nothing about OOP I think I recall reading it at one time:

"Tony Visconti rigged up a system of three microphones to capture the epic vocal, with one microphone nine inches from Bowie, one 20 feet away and one 50 feet away. Only the first was opened for the quieter vocals at the start of the song, with the first and second opening on the louder passages, and all three on the loudest parts, creating progressively more reverb and ambience the louder the vocals became."

http://en.wikipedia.org/w..%22Heroes%22_%28song%29

Ah - ok - these guys have your explanation covered the Mr. Mook!

papa, tanks.

I did say, "Although this says nothing about OOP..."

There's a song out there somewhere that uses OOP as an effect.

Beag, they had me covered like a wet blanket.

I typically mic my snare with a mic on the top and a mic on the bottom (i.e., two mic’s on the same source).  The result of toggling the phase invert switch on one of the two tracks can be fairly drastic.  From “thin” sounding to “fat” sounding.

About a year ago I discovered (actually through a recommendation on this forum) Voxengo’s PHA-979.  It is a plug-in that lets you phase shift your track.

This tool allows me to easily find the right tone between the two tracks by shifting the phase of one track from anywhere from 0 to 180 degrees.

(technically, shifting something 180 degrees out of phase is not the same as inverting the phase but I can’t tell the difference)

About a year ago I discovered (actually through a recommendation on this forum) Voxengo’s PHA-979. It is a plug-in that lets you phase shift your track.

This tool allows me to easily find the right tone between the two tracks by shifting the phase of one track from anywhere from 0 to 180 degrees. (technically, shifting something 180 degrees out of phase is not the same as inverting the phase but I can’t tell the difference)

Take a small item like a cigarette packet and flip it, then rotate it 180 degrees you will see that you are doing 2 completely different things to the orientation of the packet. You will see 'flipping' turns it upside down where 'rotating' 180 degrees reverses its orientation (facing the opposite direction).

The causes of OOP signals has been well covered here already.  So here's something else also you can use toward post take correction or even creative use of the phenomenon.

A stellar new freeware channel strip that incorporates phase shifting / alignment / flipping / rotating options in a similar way to how the well-loved but £300 Little Labs IBP box treats it.

http://varietyofsound.wor...styvcs-released-today/

Also there is also a good article with video on the subject of phase alignment from a mixing perspective (rather than recording) on the same blog.

http://varietyofsound.wor...ng-to-phase-alignment/

Of course out of phase by implication requires one signal to be out of phase with another so for example 2 microphones are out of phase and recorded to a single track then there is nothing you can do post take to correct it, it will only work if you can bring one (or more) signals (e.g track(s)) into alignment (or in the case of creating an effect, out of phase) with another whose phase will remain unaltered.

Remember this is different to time alignment in that 2 signals can be perfectly aligned and represent an exact moment in time in unison but the phase of the signals waveform can vary within that, so time alignment (or more accurately slight mis-alignment) can mitigate phase problems to a degree but will sometimes introduce a slight delay causing the sound to be back in phase but slightly 'blurred'.  Hence you will sometimes have use for a specific tool for the job.

Harsh use of eq causes phase shifts too much in the same way as the curved top of an aircraft wing introduces a detour for the air passing over it which may give an airplane the benefit of lift as the top and bottom of wing passes through the same piece of air at the same time but the phase delay induced by the curve at the top of the wing when it meets up again with the unrestricted airflow at the bottom causes all manner of turbulence in its wake.  Unfortunately with digital audio that phase of delay will remain present, unlike the turbulent air following the aircraft which will dissipate over time.

Hey, maybe using that simplified analogy I've stumbled upon the reason why my level sliders always seem to gravitate upwards during the course of a mixing session...

A cool way to see how phase affects the sound  is to use a delay effect.
 
Insert Sonitus stereo delay, set the both side 100% wet, no feedback,
Slowly sweep one side from .1 to 100 ms.   Listen to the change in tone of the product as you sweep it. 
This essentially throws the wave forms out of phase.
 
 

It's not the place you're going to
It's just a phase you're going through
- Art Garfunkel