two lavalier mics, why?

[Tong0615]

I have seen many TV Interviews, which the guests and moderator has two lav mics. I am wondering, why they need two mics? one reason in my opinion would be to have a continuity sound when the moderator turn their head to left or right, but I have also seen some situation, which two Lav Mics being placed almost in the same position, Why is this necessary? Thanks.

[Jeff Wexler]

Redundancy. If one mic fails the other can take over. This is the only reason 2 lavs are used, usually on the same mount and in the same position.

[Glen Trew]

It started with Walter Cronkite in the 70's when one of his ECM-50 lavs failed on-air. The look soon became a status symbol that other TV anchors didn't want to be left out of. The second mic (especially with local broadcasts) was often a dummy.

[Mirror]

Double rental.  I think I'll talk my UPM into it on my next show.  As in politics, scare tactics work well on set too.

[VASI]

Redundancy. If one mic fails the other can take over. This is the only reason 2 lavs are used, usually on the same mount and in the same position.

This.

[Marc Wielage]

Glen is right about Cronkite. My memory is that they switched from an EV desk mic to the Sony ECM-50 lav when it became popular around 1972, but one night the electret battery died and they had to (clumsily) resort to the desk mic again on a live broadcast. From the next show on, I think in early 1973, Walter always had two lavs, one as backup:

I have been in live on-air network situations where both mics were definitely, 100% active and neither was a dummy. I don't know if any local stations did that, but if they did it's a pretty silly idea. 

Edited August 16, 2015 by Marc Wielage

[Marc Wielage]

And I just saw a piece of a Bob Iger speech from the Disney convention over the weekend, and damned if he didn't wear two wireless lavs and windscreens at the presentation...

So even on a non-televised live event, sometimes they'll go with 2 mics, 2 transmitters, and 2 receivers... "just in case."

[soundmanjohn]

It's also usual in some theatre shows, especially for the lead performers who can't necessarily get off stage for a mic change in the event of a failure, usually caused by ingress of sweat or a cable fault. I've just done a show with Jim Dale, who's worn two complete wireless systems for musicals ever since he was in Barnum, where it was impossible for him to get off stage and mic failure was pretty common because of the acrobatic nature of his performance. I can confirm that even at 80, he's still a very athletic performer. We used two DPA4061s in a double mic mount, but never had a failure, as far as I know.

Regards,

 

John

 

 

Edited August 17, 2015 by soundmanjohn
Added stuff

[Mungo]

Sennheiser ME 102 and ME 104 look almost exactly the same. I've seen a combination of these two.

 

In a live show with audience this makes sense:

ME 102: Omni mic. rich frequency range, no pop and rumble noise: best for recording sound

ME 104: Cardioid mic. making PA mixer happy.

[ao]

even with 2 lavs,  things can go south,  as was seen during the ford/carter debate in 1976:

 

http://thiswastv.com/2012/08/22/debate-night-fordcarter-1976/

[Karri]

If memory serves me right, anchors of the Finnish Broadcasting Company only have one lav, but they have several Schoeps CCM mics (painted white) on their white desks as backup.

[Jay Rose]

You'd be amazed how many students are being taught that the dual mics are for noise control, using come kind of phase inversion*! I've seen this on lots of recording and sound forums.

(*And some kind of miracle physics, since the dual lavs are nearly coincident.)

[Abe Dolinger]

Heh. I had someone ask me to do that with a highway on a feature scout. "Can't you just invert the phase on a second mic and cancel that out?" I didn't end up working on that movie.

[jrd456]

Heh. I had someone ask me to do that with a highway on a feature scout. "Can't you just invert the phase on a second mic and cancel that out?" I didn't end up working on that movie.

It doesn't work with traffic but can work [to a certain degree] with a constant noise like a generator using two trks---one for dial. and one for generator [inverted] and mixed in carefully in post ---It has cut the B.G. for me when carefully done in the right circumstance where the actors are static and using EQ as well.---remember if it doesn't work,no damage done.

 

                                                                                                                        J.D.

 

 

[Abe Dolinger]

I'm glad you had some success with it! I feel like constant noises are much easier to remove in RX. I had trouble matching the frequency response of the noise on the dialog mic with the "noise" mic. Maybe I gave up too soon.

[Marc Wielage]

I agree with Abe: I think iZotope RX is a far better solution than trying to use phase cancellation on the set with multiple microphones. You're also going to hear a lot of of level "pumping" with the phase cancellation technique, and it's not very controllable.

[Jay Rose]

Well, phase inversion actually gets rid of the sound. It can be hard to wrangle, but I've also had some success.

The single-track techniques that measure a sample of just noise, and then process the dialog, is merely masking the offending noise under dialog. It can work well - and I could not live without RX4 - but it's just not the same thing as removing the noise. 

(Filtering can remove the noise... if the noise is pitched. Otherwise, it's not a viable choice.)

[mikewest]

Yep redundancy on live broadcasts

I've operated booms with two mikes on live to UK television!

mike