phase?.. (1 Viewer)

[stevieb]

i have read tutorials on the net about this and still cant understand how to know if a mic will be in or out of phase?..

i have a good understanding of physics and sound waves and alike so please explain..

 

[RED(tape)MENACE]

How to know?
Unless two mics are identical, and in exactly the same position (as in, occupying the same physical space) then they will be out of phase, due to the time difference between sound reaching the mic's capsules.

The different arrival times, and therefore the mismatched waveforms of each microphone's pickup of sound results in comb filtering, where certain parts of a sound's frequency range are reduced, boosted or even cancelled altogether.

Practically, the way to avoid phase issues are :

1. Have mics as close together as physically possible, with diapraghms aligned. This is more likely to be possible where you're setting up to capture in stereo for overheads or whatever.
2. Move mics around until flipping the phase switch on your desk or daw gets you in phase. The easiest way to check this by ear is to listen in mono - when signals are out of phase they will tend to lack in bass.
In mix for example, when getting your drum sounds together, you might start with the overheads, then add in your kick mic. Flip phase, and whichever setting has more low end would be the 'more' in phase of the two. Rinse, repeat for the rest of the mics.

Enjoy.

 

[the departed]

this is something that has always baffled me. also worries the hell outta me..
ive never checked to make sure mics are in phase or not.

 

[RED(tape)MENACE]

ive never checked to make sure mics are in phase or not.

Always be checking, at the very least in mix.

 

[the departed]

so just keep an ear out for the missing low end? is there a more "sure fire" way of telling?
im glad this thread reminded me about this..
ive looked at speakers and phasing before but not really thought about mics.
i always though it was something id never have to worry about! ha. sounds like a disease!
grand so when i get into the studio again ill check it out.

would most/all desks have phase switches?

 

[kings lead hat]

feels likje ur gonn a puke when u hear it

put desk in mono and listen to the 2 mics. move 1 till it sounds really shit and right heavy w/ no bass then at its worst point flip the phase on the desk and youll b nearly 100% in phase.
check phase of over heads 1st (relationship between)
then check o/h vs. bass drum get em all in phase andd ur a wkd engineer .......well not really

 

[kings lead hat]

phase button=most desks do but u can make 1 with an xlr. make it out of phase by fucking w/ the wiring. there should be loads of tutorials on the web for this.
think its called a crossover cable

 

[RED(tape)MENACE]

Another good way to hear crazy phasing is to phase flip one half of a stereo mix.
It'll be pretty obvious that something is fucked.

 

[the departed]

cool. right now my brain is hurting from this but once i get into the studio and try all this shit out it should make sense.
thanks

 

[stevieb]

thanks..

 

[kraster]

Nice phase explanation, Pete.
And good tips, Kings Lead Hat. (Is that your real name?)

One thing to bear in mind is that the phase switch on a desk/pre isn't exactly a phase switch. It's a polarity switch. In other words it flips the signal 180 degrees. Obviously this results in a mirror image of the signal but at the heart of it it's an electricaltrick. But It will get you closer to in phase in some cases.

There is the little Labs Analogue Phase alignment tool that actually adjusts the phase as opposed to flipping the polarity. It's really effective. But it's price is ridiculous. I believe there is a freeware plugin that does similar stuff.

Also, any non-linear eqing will also screw up the phase of your signal. 99% of eqs are minimum phase eqs. You can get pricey Linear phase eqs but as long as your careful with these you won't need the 8,000 for the single channel weiss eq.

You can spend many hours on a Mix flipping various things in and out of phase without each other but the results are worth the effort. I've had many a great moment flipping the polarity of a kick drum to reveal all the low end information that has been misiing.

One of the big phenomenons with phase is masking. Say you have a Bass and a Kick drum. Sometimes it's hard to hear a kick drum behind the Bass or vice versa. Altering the phase relationship between them can give each other it's own space. Or bring one forward or push it backward.

It's a big issue. There's phase distortion everywhere from your Microphone to your speakers. It's one of the most crucial aspects of getting stuff to sound good.

 

[MrT]

Thats not actually true.. if they are exactly the same distance they can be in phase, its just unlikely

How to know?
Unless two mics are identical, and in exactly the same position (as in, occupying the same physical space) then they will be out of phase, due to the time difference between sound reaching the mic's capsules.

The different arrival times, and therefore the mismatched waveforms of each microphone's pickup of sound results in comb filtering, where certain parts of a sound's frequency range are reduced, boosted or even cancelled altogether.

Practically, the way to avoid phase issues are :

1. Have mics as close together as physically possible, with diapraghms aligned. This is more likely to be possible where you're setting up to capture in stereo for overheads or whatever.
2. Move mics around until flipping the phase switch on your desk or daw gets you in phase. The easiest way to check this by ear is to listen in mono - when signals are out of phase they will tend to lack in bass.
In mix for example, when getting your drum sounds together, you might start with the overheads, then add in your kick mic. Flip phase, and whichever setting has more low end would be the 'more' in phase of the two. Rinse, repeat for the rest of the mics.

Enjoy.

 

[kraster]

Thats not actually true.. if they are exactly the same distance they can be in phase, its just unlikely

No they can never have the same phase. Unless, as redtape pointed out, they occupy the same spot.

If you have to equidistant Mics they might have the same phase response at certain frequencies but at other frequencies they will have different phase response. This is because of reflections in the room, uneven phase dispersion from the source, differences in Mics, pres and cables, and a whole load of other stuff. This is why we get comb filtering.

In order for two Mics to have identical phase response they need to occupy the same physical space. Which is impossible.

Even if you had an anechoic room with little to no reflections and Mics pres, cables etc. that were nearly identical and a source that had even phase dispersion they still would not cancel out.

So for all real world applications it's not just unlikely it's practically impossible.

 

[Frobisher]

Sometimes it's not a question of which is more or less out of phase and it's more important which you prefer. I've had this where I've flipped the phase on 2 mics on a snare and it's not a question of which has less phase problems but which one sounds better. As always use your ears.

 

[the departed]

hey i got into the studio tonight to try out some things with phasing.
firstly i just had the kit on 2 overheads. changing the phase on one of them made a massive difference to the clarity. as i listened back to the fully mic'd kit though, i couldn't hear any difference if i switched phase on any of the other mics.
more investigating to be done..
but even the difference on the overheads is quite pleasant.
anybody got any quick tips on getting a "bigger" bass drum sound? like something that isnt just a "thud".

 

[dudley]

bono does a cool thing using phase that i've always wanted to try

basically, he gets uncomfortable recording vocals wearing headphones in a booth, so they just set up a mic in the control with the engineer, so he can stand between the monitors with the music at full blast. the speakers are put out of phase so that none of the playback is actually picked up by his mic

smart

 

[ernesto]

bono does a cool thing using phase that i've always wanted to try

basically, he gets uncomfortable recording vocals wearing headphones in a booth, so they just set up a mic in the control with the engineer, so he can stand between the monitors with the music at full blast. the speakers are put out of phase so that none of the playback is actually picked up by his mic

smart

and he only ever records with sm58s too. surely hed need two mics though? no?

 

[kraster]

bono does a cool thing using phase that i've always wanted to try

basically, he gets uncomfortable recording vocals wearing headphones in a booth, so they just set up a mic in the control with the engineer, so he can stand between the monitors with the music at full blast. the speakers are put out of phase so that none of the playback is actually picked up by his mic

smart

Here's a cool tip similar to above.Only really works with the Mic on a stand.

Record a vocal track with the speakers on.
After you've done that don't touch anything.
Rerecord the music on a new track on your tape/Daw through the speakers (without the vocals of course!)

Solo Both tracks.
Flip the polarity on the second track.
Bounce to Disk with these settings.
All you should be left with is the vocals with a little spill from the backing track.
Handy for the fussy/anti-headphone Mob.

 

[Beanstalk]

Here's a cool tip similar to above.Only really works with the Mic on a stand.

Record a vocal track with the speakers on.
After you've done that don't touch anything.
Rerecord the music on a new track on your tape/Daw through the speakers (without the vocals of course!)

Solo Both tracks.
Flip the polarity on the second track.
Bounce to Disk with these settings.
All you should be left with is the vocals with a little spill from the backing track.
Handy for the fussy/anti-headphone Mob.

In the ideal world maybe...but surely the backing track is being obscured in the first take by the singer standing in front of the mic, so when you try to cancel it out with the reverse phase, its not perfect cancellation.

I'm sure it would be OK, if the backing track was the final arrangement, as the leftover would get lost in the mix, but if not, it might be noticable, no?

 

[RED(tape)MENACE]

Tried the record the room and flip thing recently.
It does work to a certain extent alright.

Must try the out of phase speakers thing.

Another good one I've heard is.. uh, kinda hard to explain.
So I drew this retarded picture :

So. You've got a big yellowish circle.
This represents the singer.
(insert singer joke here)

You've got two identical mics -
One aimed at the gob, another shooting above the noggin.
Get them aligned as closely as possible.

Flip phase on the top one -
The thinking is that pretty much the only thing the bottom mic is getting that the top mic isn't ... is the vocals.