Two lavs, one with the phase flipped?

[cory]

There is a potential shoot with 4 people improv-ing in an uncontrolled bar location.

Has anyone had success with this technique? I am curious to know people's experiences...

[Soundwil]

4 people, 2 lavs, phase flipping of one of the lavs! I don't understand.

Don't flip the phase of the lav unless you think they are wired incorrectly - it will cause all sorts of probs.

[cory]

Let me clarify... 2 lavs on each person. Like noise cancelling headphones

[Jon Gilbert]

Do you like making things hard for yourself? Sounds like a terrible idea!

[Benjamin Gandy]

In order for that to work even slightly the capsules would have to be side by side, i.e. the lavs would basically have to be taped together, and that means the voice will also be affected by the phase flipping. Unfortunately there's little you can do to improve sound in an uncontrolled bar.

[Bill Kole]

Though typically larger than a powered lav, a dynamic lavaliere can be effective in reducing off-mic noise.

[Jeff Wexler]

This whole idea of using phase cancellation has been around for a long, long time...  and you know what, it doesn't work. Thinking that using 2 lavs out of phase with eachother has anything to do with how noise canceling headphones work is just wrong. 

[chris_bollard]

Surely it's easier to just get the placement right for one mic per actor?

[Soundwil]

Best bet is mic placement and iso track IMHO.

Should be fine if there isn't any music audible.

[jrd456]

The idea of phase flipping is to have a second mic.just recording the unwanted sound. I don't know if it would do much for crowd wala.It did work for me once with a constant generator hum.There's no dangerof screwing it up if you use separate tracks and experiment in post.It probably would be more trouble than it's worth and unless your doing post,they will screw it up.

J.D.

[seth]

Im guessing your goal is for clean dialogue? Try dan Dugan auto mixer.

[John Blankenship]

The one instance where the out-of-phase trick can work is with a vocalist -- typically, with rock. Two 58s strapped together, wired out of phase, with the singer's lips right against the grill of one of the mics. What allows this to work is the ratio of the distance from the mouth to each microphone. It will color the sound some, but is a trick that can be employed to improve gain before feedback of loud stage monitors.

In the current era of more sophisticated and better tuned sound systems, and the widespread use of IEMs, I doubt that you're likely to see it deployed.

So, how you'd manage to have a pair of lavs picking up the same exact sound field, while achieving a high ratio of dialog discrimination between the two lavs, is beyond me.

Much better to spend time learning the craft than trying to trick it.

[Jay Rose]

For the polarity-flip technique to work, the 'distant/flipped' mic has to be far enough away from the mouth that voice doesn't get picked up and cancelled, yet close enough that it picks up interfering waves while they're reaching both mics in the same phase.

 

 

Then, and only then, will the flipping cancel the offending waves. 

 

It worked for the Dead because Garcia was eating the close mic, and inverse square made that mic a -lot- louder while still keeping both mics together. Can you shove lavs into the actors' mouths*?

 

Physics tells us this is only likely for low frequencies in the offending noise... well below normal walla frequencies, which is what presumably you're trying to get rid of. It's possible at other frequencies as well, but the effect will be so random and depending on frequency/distance as to be unpredictable, 'phasey', and useless.

 

Bottom line: there are good scientific reasons for other peoples' advice to skip it.

 

--

 

*Want clean sound in an actual working bar? Convince the director to shoot profiles, and use E6 or similar head mics.

[John Blankenship]

It seems several of us replied at the same time.

Another issue, and right in line with what Jay said, is that the response curves and patterns (and, yes, even omnis have patterns) of lavs tends to vary more widely from unit to unit than does, for instance, a Schoeps.

[studiomprd]

" 4 people improv-ing in an uncontrolled bar location. "

Not only do I completely agree with all the advice above, but I also question what the moviemaker really knows about making movies.

[bmfsnd]

Well-placed lav on each actor, hope for the best (and that there is no music playing)

[jitter]

Sometimes in a musical theatre show a reversed polarity lav can solve some momentary problems when you are designing a show and your scene is so crowded and you don't have enough fingers to mix. But use this technique very carefully, it can do more worse than better. Head to head situations, choose one mic and mix to taste.

[Zack]

 

Don't flip the phase of the lav unless you think they are wired incorrectly 

You mean polarity 

[old school]

Wireless mics & ISO'd tracks and killing the music is your only hope.

CrewC

[atheisticmystic]

 

Much better to spend time learning the craft than trying to trick it.

 

(If you listen closely, you can hear my dremel tool etching this into the wall of my edit bay)

[Marc Wielage]

Im guessing your goal is for clean dialogue? Try dan Dugan auto mixer.

 

Yes, I would vote for regular lavs, good placement, control the noise as best you can, and use an auto-mixer. (The one in the SD 788 can be useful in some cases.)

[pkautzsch]

Killing the music will also (sometimes) make the walla get softer, because everybody doesn't need to shout over the music, and over each other.

The clue to shooting there is, like others have said, to get the lav as close to the mouth as possible.

You might set up a "background" mic (or two) to pick up only the walla. This can help a lot to smooth out edits when on separate tracks. Don't include that mic in your mix.

 

And: make sure production and post know about that location's sound issues. You don't want this to fall back on you.

[Soundwil]

You mean polarity 

Yes, I mean flipping the polarity (which shifts the phase by 180º).

 

From the 552 manual:

"The polarity (sometimes referred to as a phase inversion) of inputs 2 and 4 can be reversed"

 

From the SQN 5S manual:

"The [PHASE] switch acts on CH2, independently of the settings of the other switches. When it is moved to the right (arrow), it inverts the phase of the signal"

[Christopher Mills]

If this is not scripted, and not a fiction project, I would go so far as to consider headworn b6 mics.  and even if scripted.. perhaps b6 on top of ear hidden with medical adhesive/hair/hats

 

Or... b6 in brim of hat..again.. this amounts to getting the lav as close as possible to the mouth of speaker..

 

Also, tell the producer that if you leave the  bar music on, they will pay a fortune in clearances on the music.

[jrd456]

Before the shoot,tell them they don't want to pay royalties for the music.Music will destroy the project and make the editor go insane.

 

J.D.