Phase and Anit-Phase

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Mans reach exceeds his grasp
Member Since: Oct 23, 2007

I wasn't sure where to post this, but this seems like the correct 'file under' as I usually cover this post mix.

I simply dont understand Phase and anti-phase in their own rights.

I would like to know more about these two things in your own words and how they effect our work specifically.

Also, is it 'Bad' to leave anti-phase signals in a work to be mastered? Or should anti-phase be worked out of the mix?

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MASSIVE Mastering, LLC
Member
Since: Aug 05, 2008


Aug 23, 2010 12:03 am

If you're talking about inverted signals (the only thing I can assume with "anti-phase" although I've never heard the term in the typical recording lexicon), that's something that really needs to be worked out with microphone placement. You can certainly affect phase relationships between two discrete signals during the mixing process -- Nothing positive (no pun intended) can be done about phase issues during the mastering process...

But anyway - Perhaps a little more clarity on what you're referring to before anyone jumps to any conclusions...?

EBONY AND ACE's
Member
Since: Jan 05, 2009


Aug 23, 2010 03:42 am

Hey Keith,

i assume you mean something like out-of-phase, which is actually important for
stereo mixes. its more or less also some kind of a psycho-accoustic thing.

from the physics, take your tape recorder or cd player, there are two outputs.
these two outputs for left and right channel run 4 separate cable. each side one
should be a minus and the other the phase/lead (or plus as we german call the
polarity), put this cables with this polarity to the mixer or amplifier. thats in-phase.

both signals (l+r) together play back the mix and you have the impression of a
three dimensional sound from two (dimension) speaker. whereas usually the vocs,
bass and drums are in the center and some keys or guitar are panned more or less to
the sides.

when you switch the polarity you switch the whole mix to something else.

try to switch the polarity of a stereo mix and pan both sides to the middle
you will get the impression of a karaoke sound, missing the centre instruments.
the reason is that the frequencies simply delete themselves.

the best example for this is the guitar pick up, the humbucker: two coils run
out of phase and elemenate buzz humming. or the sound of position 2/4 on a strat.

this can happen to two identical signals coming from microphones as well. imagine
you run two mics in front of a guitar cabinet. some frequencies can be deleted
when running the mics together. it sounds hollow and baseless, muddy.

there is a simple rule to avoid phasing trouble for mics: the distance between
the two microphones must be three times higher than the distance to the sound source,
this is based on the speed of sound in air (343m/sec at 20 degrees)

that are some reasons i know why the correct (or recorded) polarity is quite important.

there are many more and deeper explainations for that in the net i guess.

take care and stay tuned!

Mans reach exceeds his grasp
Member
Since: Oct 23, 2007


Aug 23, 2010 08:30 am

As referenced in the lower left of this image?


http://www.waves.com/objects/Images/Screenshots/sshot_big_paz01.jpg



What does it all mean!!

I think that's a good explanation of it joerg

Typo Szar
Member
Since: Jul 04, 2002


Aug 23, 2010 08:59 am

I wouldnt worry too much about the phaseoscope n such, it kind of works as a confirmation of wat ur hearing, but first u have to hear it.

basically like everyone has said phase alignment and "antiphase" r just two sides to the phase coin. That is since sound travels in waves, the peaks and troughs, bottoms and tops of the W basically, work off eachother. Its very noticeable when the two waves r created by teh same original sound becoz they react off eachother in a very definite way.

Back to the W, if u took an M and put it directly over W and said every part that is being mirrored between them has to be taken out, ud be left with nothing. If u schooched M over a bit so it wasnt directly over W, than only a few parts would be removed. If u replaced M with a Q, than no parts would be removed so on and so forth.

The thing about phase is, there is no real perfect alignment. Commonly... obviously u dont want an M over W situation, coz u would have nothing, but maybe u want a little bit of M or W, coz the resulting new letter is wat ur looking for? it can happen.

If all of that was gobbledegook, check out this video, its an ad basically, but u can actually "hear" how phase alignment works and wat r its merits

www.gearwire.com/radial-phazer-demo.html

ull realize after the vid that different phase alignments create different results, but ultimately its u as the mixer who must determine wat is hurting or helping ur recording. The scope again is just a confirmation, if u feel like ur sounding is oddly thin for the instrument, check ur phase scope, it may be showing phase problems (any spikes beyond the two side blue lines). There will always be some amount of phase cancellation going on, but again if it sounds ok, than ur gold.

MASSIVE Mastering, LLC
Member
Since: Aug 05, 2008


Aug 23, 2010 11:57 am

The best thing to do (IMO/E) is dump the meters.

A) If you can't hear phase anomalies, you'd better learn to - Quickly.

B) A meter isn't going to tell you what sounds good. Or if the side information (which is really what we're looking at here) is "typical" or not. It's just going to tell you that there is some side information (which again, you should be able to distinguish easily).

The only way to have a mix with no side information is for that mix to be 100% mono.

THAT SAID -- There is certainly "problematic" side information (I can pick out a dozen discs where the guitars all but disappear when the mix is summed to mono). That's not going to be fixed during the mastering phase -- That should have been handled when the engineer was positioning the mics or shifted during mixing if he couldn't hear the problems during tracking.

Mans reach exceeds his grasp
Member
Since: Oct 23, 2007


Aug 24, 2010 03:58 am

Massive- just got done reading your posts from another forum on this matter. The original poster really stirred things up!

I was wondering out of sheer curiosity.

I don't use the meters for anything other than trying to find a rouge frequency from time to time.

Cool video btw crux. The explanation was nice too :)

MASSIVE Mastering, LLC
Member
Since: Aug 05, 2008


Aug 24, 2010 12:03 pm

Geez... I could only hazard a guess at who & where... The whole "meters" thing is a pop-pick.

But that's what they're good for -- The occasional "What the hell was that?!?" moment.

And of course, to insure proper calibration of the chain. If the chain is properly calibrated, meters are of little use 90% of the time.

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