Phase and Polarity

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Phase and Polarity

Postby Alain Benoit » Fri Nov 23, 2007 11:27 am

Discuss.
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Postby Mathieu Benoit » Fri Nov 23, 2007 11:28 am

Jinx!!!!!
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Postby Scott DeVarenne » Fri Nov 23, 2007 11:35 am

Umm... phase is good... or bad.
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Postby Alain Benoit » Fri Nov 23, 2007 11:35 am

Jef wrote:The phase issue occurs when the same signal is captured from two (or more) distances. Depending upon the amount of difference in distance between mics will determine at which frequency you may have a problem.
When you have 2 waves in sinc with each other the amplitude is increased. If the waves are directly out of phase the signal gets canceled out altogether. Anywhere in between and you get varying degrees of boost and cut at various frequencies.
So, basically what you will hear is a tonal difference, sometimes subtle or sometimes extreme as you blend the two signals.


Because phasing is rarely an on/off or 0/180 issue, one of my favourite little problem solver/audio gadget companies have addressed this handsomely.

Enter the Little Labs IBP Analog Phase Alignment Tool.

Of course for you DAW users out there, this thing is a paper weight, but for old school guys like me or live, they're great.
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Postby macrae11 » Fri Nov 23, 2007 11:46 am

Drumwaiter wrote:So when a single source is being recorded by more than one mic (like drums), how do you avoid unwanted distortions of the sound of the source, through proper mic placement? Also, is there any way to use this particular phenomenon to the benefit of the sound?


Matt posted this in another thread. I'm just consolidating the two.
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Postby Alain Benoit » Fri Nov 23, 2007 11:54 am

That is what I thought I had just done. At least that is what i was attempting to do when I quoted Jef's response to Matt's phase question in my reply.
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Postby Mathieu Benoit » Fri Nov 23, 2007 11:54 am

Dammit Alain wins! Stupid Alain and his stupid clout.... Oh well. :-P
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Postby Mathieu Benoit » Fri Nov 23, 2007 11:55 am

No Al, actually the both of us opened a new "phase" thread at the same time, independant of the snare mic thread.
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Postby Alain Benoit » Fri Nov 23, 2007 11:56 am

All I did was follow up on Matt's suggestion of starting a seperate thread from the 'Snare Micing' one and beat him to the punch!

Thus I assume the,


Drumwaiter wrote:Jinx!!!!!


If you will very carefully scroll to the top of this page you will see that the first post is by yours truly.
Last edited by Alain Benoit on Fri Nov 23, 2007 11:59 am, edited 1 time in total.
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Postby Mathieu Benoit » Fri Nov 23, 2007 11:57 am

Yes, you did beat me to the punch. So, can someone answer my latest question? It's now in a quote in MacRae's post.
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Postby Alain Benoit » Fri Nov 23, 2007 12:02 pm

Drumwaiter wrote:So when a single source is being recorded by more than one mic (like drums), how do you avoid unwanted distortions of the sound of the source, through proper mic placement? Also, is there any way to use this particular phenomenon to the benefit of the sound?



Mic placement is one, eletronic phase alignment is another, ultimately it is your ears. Sometimes phasing does not always work against you, its all half relevent and half taste.
I do not always phase flip a double mic'ed snare or bass DI/mic combo just as a matter of course, I listen first.
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Postby Jef » Fri Nov 23, 2007 12:58 pm

Alain Benoit wrote:...ultimately it is your ears. Sometimes phasing does not always work against you, its all half relevent and half taste.
I do not always phase flip a double mic'ed snare or bass DI/mic combo just as a matter of course, I listen first.

Absolutely. You may also find that some phasing may be, depending on the sound you are going for, a pleasant effect, especially when panning things around in the stereo field. But also remember, this effect may sound pleasing in the studio monitors or headphone mix, but doesn't always reproduce as well in the basic consumer grade 'boom box'. The closer the speakers are together, the more phase cancellation will occur.
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Postby Alain Benoit » Fri Nov 23, 2007 1:09 pm

Jef wrote: But also remember, this effect may sound pleasing in the studio monitors or headphone mix, but doesn't always reproduce as well in the basic consumer grade 'boom box'. The closer the speakers are together, the more phase cancellation will occur.


The closer the speakers are together the more of a point source you have, (read MONO).
That is why all recording consoles have a check mono sum function.

I remember a local artist being recorded in a local studio. The engineer/studio owner brought the master over to my facility to get my critique. First thing I did was hit the mono button in the monitor section. as soon as I did this the guitars dropped out almost completely. All that was left was the snare drum. This album was a sort of carreer retrospective for a local semi-famous guitar player.
I told the engineer that things would be fine as long as it was never on TV or no one ever woke up to it on their radio alarm clock. :shock:
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Postby macrae11 » Fri Nov 23, 2007 1:09 pm

Drumwaiter wrote:Dammit Alain wins! Stupid Alain and his stupid clout.... Oh well. :-P


No actually there were already a couple of posts in Al's thread so it was easier to just have to move one post.
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Postby Jef » Fri Nov 23, 2007 1:20 pm

Alain Benoit wrote:The closer the speakers are together the more of a point source you have, (read MONO).

Right, that's what I was getting at. Thanks Al for simplifying it.
In the stereo field things may sound really good.
Some TV's, Boom Boxes, Radio Alarm Clocks, etc. don't produce the same stereo effect.
Always test to a mono source first.
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Postby Jef » Fri Nov 23, 2007 1:31 pm

...just noticed I've been promoted to bronze.
Woo hoo! 8-)
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Postby Mathieu Benoit » Fri Nov 23, 2007 1:59 pm

Alain... Am I going to have this problem on my rig, since I don't have a "mono" option? Since I do mostly tv soundtrack, and filmscore stuff lately. Am I creating problems here that I'm not even aware of?
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Postby Mathieu Benoit » Fri Nov 23, 2007 2:01 pm

Jef wrote:...just noticed I've been promoted to bronze.
Woo hoo! 8-)


Dammit. I wish I was a bronze member status! I'm just a dumb "Matt Benoit" status... :cry:

:-P
Last edited by Mathieu Benoit on Fri Nov 23, 2007 2:30 pm, edited 1 time in total.
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Postby Jef » Fri Nov 23, 2007 2:19 pm

Drumwaiter wrote:Alain... Am I going to have this problem on my rig, since I don't have a "mono" option? Since I do mostly tv soundtrack, and filmscore stuff lately. Am I creating problems here that I'm not even aware of?

This was directed to Alain, but I think I can answer it for you Matt.
Even if you do not have a 'mono' option on your rig, you can achieve a mono source by panning everything to center.
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Postby Mathieu Benoit » Fri Nov 23, 2007 2:28 pm

You mean the final mixdown? Just export a mono file for reference?
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Postby Jef » Fri Nov 23, 2007 2:34 pm

yeah.. or you could do that. ;-)
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Postby Mathieu Benoit » Fri Nov 23, 2007 2:36 pm

So phase can become an issue even beyond the actual miking of the source?
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Postby Jef » Fri Nov 23, 2007 2:52 pm

Drumwaiter wrote:So phase can become an issue even beyond the actual miking of the source?

Uh huh, the principle is the same whether the signal is in the electronic realm or in the acoustic world. Only difference is the effect of outside influences when it's an acoustic signal. ie room shape and size, speakers, and numerous other variables.
Any phasing issues can be heard simply by bringing your sources to the center of the mix (mono). If you don't have the test equipment, this is the simplest way to check for phase cancellation.
You will definitely hear it in mono if there will be a problem.
Last edited by Jef on Fri Nov 23, 2007 3:12 pm, edited 1 time in total.
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Postby Mathieu Benoit » Fri Nov 23, 2007 3:07 pm

excellent! Thanks guys!
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Postby Malcolm Boyce » Fri Nov 23, 2007 3:28 pm

Drumwaiter wrote:Alain... Am I going to have this problem on my rig, since I don't have a "mono" option? Since I do mostly tv soundtrack, and filmscore stuff lately. Am I creating problems here that I'm not even aware of?
Hmmmmmmmm.... Sonar has a Mono button... :roll:
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