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Old July 26th, 2007, 02:25 PM   #1
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Proper way to mix for two actors, and a boom

Hey all, I'm wondering which is the PROPER way to handle audio with two wireless lavs (only two actors) and a boom. Does one hard right pan channel one for the first actor, hard pan left for the second (channel 2), and float the third channel (boom) over center (channel 3)? By the way, the two channels will feed directly into the camera, there will be no DAT or multi channel recorder. Thanks
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Old July 26th, 2007, 02:59 PM   #2
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I would rather have two clean channels without the third mixed in. It would make life easier in the editing room without any overlapping dialog.
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Old July 26th, 2007, 03:07 PM   #3
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Amen to Emre's comment. The arrival time differences between the actor's sound hitting the lav and the arrival of the same sound on the boom means that a distortion free mix of the two is going to be difficult unless you have a location mixer who is riding gain all the time. Putting Actor 1 on one track, Actor 2 on the other, and forgetting about the boom altogether OR using the boom with an experienced operator who can keep the mic positioned properly and forgetting the lavs would be the preferred way to go.
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Old July 26th, 2007, 03:39 PM   #4
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Ahhhh, I'm somewhat in aggreeance ("Gee, is that a word?" haha) with you both. My guess is the director wants to pick up "Some" ambient sound with the boom. My initial thought was with the latiency (spelling?) on the Lectrosonic 411's (3ms?) might mean a bad echo altogether? The scenario I first mentioned would only be useful if we were recording to a four channel recorder, and had each on their own channel - think I'll follow what was said here, thanks guys.
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Old July 26th, 2007, 03:45 PM   #5
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Record the ambience at the end and mix it in post.
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Old July 26th, 2007, 04:37 PM   #6
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Another way of doing it is:
Channel 1: Record the boom only.
Channel 2: Record the lavs. Your sound mixer should ride the levels on the lavs to balance them out a little.

If the two lavs are very close to each other, you should turn the gain on one of them completely down... otherwise you get phasing issues. The same sound is picked up on both lavs, but with a slightly delay between them.

If you know the boom is definitely too far away / no good, then you might as well forgot about the boom and just record the wireless lavs onto their own channels. IMO.
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Old July 26th, 2007, 05:04 PM   #7
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I'm assuming this question is being asked because you're forced into this situation. If so, I go with Glenn. A lot of times though, when I think I need extra mics it turns out we could have gotten the footage some other way. If one of the speakers only has a short line you can usually record that for just sound (after the take) and drop it in later. Make sure you have lots of tone on this one.
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Old July 27th, 2007, 12:42 AM   #8
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Gary, your initial 3 channel idea is perfectly doable. You just need a plugin that will split 3 channel stereo. I believe it's left minus right or right minus left, but that may be another technique.

The basic idea is that you're encoding similar to Dolby ProLogic. Anything that's in the Left + Right equally plays through the center channel speaker, and then anything that's slightly off to one side or the other (or further), will be panned between the left and right and left out of the center entirely.

So.. If you centered the boom mic and panned the lavs hard left and right, you'd have 3 channels. You just need to be able to extract the center channel to a 3rd track and you'll be all set. There should not be any quality loss from this multiplexing process, and to compensate for the slight delay you'll have (about 1 millisecond per foot) between the boom and the lavs, just drag the boom mic track to the left by 1 or 2 milliseconds.

You won't hear an 'echo' of any sort from the delay. The only thing you'll notice is phase cancellation or reinforcement, meaning the lavs may sound good and then when you add the boom mic in, the voices sound strange and by adjusting the timing of that track by 1 or 2ms, you'll correct the problem. You can use the 3 to 1 rule when you shoot to compensate for that problem. Basically the boom needs to be at least 3x the distance from their mouths that the lavs are. So if the lavs are 8 inches away on their chests, the boom needs to be at least 24" away. Then you shouldn't have any phase cancellation problems, and you'll capture the ambience and you'll have a nice backup in case someone scratches their collar or something and ruins the sound your lavalier captured.

Hope this helps :)
Eric

P.S. For everyone's benefit, a flanger sound occurs in the single digit millisecond range, and a chorus sound occurs up to about 30 milliseconds.. Beyond 30ms, you'll hear a delay/echo sound. :)
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Old July 28th, 2007, 04:44 AM   #9
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Thanks for all the great feedback. Thought I'd share the way I decided to handle it today:

The two Lectrosonic 411's with COS-11 lavs - channel 3 & 4, hard panned right to camera channel 2

Boom mic (Shoeps CMIT 5U) to channel 2, hard panned left to camera channel 1

Channel one on my Sound Devices 442 mixer) was kept "Open" so when I just used the boom (no lavs), I switched the cabling to channel 1 which was centered, and of course fed both channels on the camera (no channel 3&4).

I figured any dialogue with two people - "Why would anyone want ones voice louder than the other?" So I just balanced both talents level the same.

I made sence to me, and sounded great for both indoor and out micing.

"Just goes to show - there more than one way to skin a cat"

Cheers!
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Old July 28th, 2007, 07:21 AM   #10
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The only fly I see in your ointment would be the situation in which the two lavs were close enough so that talent A's voice was getting into talent B's mic and vice versa.

When this happens, you get a time delay, as previously mentioned. This makes for some phasey sounding audio. Usually not as much of a problem if you're outside.

The problem can be exacerbated by having one talent with a MUCH LOUDER VOICE than the other. You turn up the quiet talent mic to get good level and the LOUD voice becomes too prominent and is also phasey.

As far as moving the boom to channel one is concerned. Why were you using the boom and two lavs on two talent in the first place?

Dunno. There's this thing some people have locked on to about "must have boom and lav!!!"

When I ask about it, they aren't sure why. They usual answer is JUST IN CASE. I ask, "In case of what?" Many are not sure. It's just something they have heard. In a lot of cases, that can do more harm than good.

I have had producers ask me for boom and lav split track on one talent. One guys says he likes to mix the two. I'm guessing he may have been working inside with a shotgun on the boom and not a hypercardioid. Shotguns suck for indoor use unless you're on a shooting stage or in a really big non-reflective space.

So you were shooting two people. Was there a boom op to follow the dialog (move the boom from one person to the other)?

Regards,

Ty Ford
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Old July 28th, 2007, 10:05 AM   #11
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Quote:
Originally Posted by Ty Ford View Post
...
When I ask about it, they aren't sure why. They usual answer is JUST IN CASE. I ask, "In case of what?" Many are not sure. It's just something they have heard. In a lot of cases, that can do more harm than good....
Yea, I get that also. It seems that these types prefer to use the Lav and want a backup in case the Lav has problems.

I guess, it's good to have the body mic option during the wide establishing shots when you really need the audio...but, most of the time I'd prefer to send two levels of the boom to tape. I pan the track left so that the right track is about 6 db lower as a safety track for those pesty transcients.
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Old July 28th, 2007, 10:14 AM   #12
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In documnetary interview situations, the boom is the 'back up' in case of failure or 'rustle' problems with the lav. Of course, you're only dealing with one source in that case, different situation.
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Old July 28th, 2007, 11:10 AM   #13
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If it's a locked down shot, I lobby pretty heavy for the boom mic ONLY if the shot is such that I can get a boom close enough. If I know we're headed for a wireless lav, I'll just start with it.

For the pureness of sound, I haven't found a lav that sounds as good as a Schoeps cmc641 on a boom.

My SD 442 mixer has very nice input and outputt limiters. For (gasp!) unattended use, seting gain on onne level a little lower is good, but if I'm actually doing the audio, in most cases, the differential isn't really needed.

I have run into a few situations where the talent emits occasional LOUD words or LAUGHS. The limiters are very helpful, but even with them, setting staggered record levels can help.

Regards,

Ty Ford
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Old August 7th, 2007, 03:52 AM   #14
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Just got word from the producers of this shoot and they are very happy with the audio (When I was on location). The options they had with the boomed audio on channel 1, and the lav's on channel 2 worked well. Must admit those COS-11's rocked! The CMIT 5U is a very tight mic, but when used/placed properly, it is "Sweet".
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Old August 7th, 2007, 03:52 AM   #15
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Cool, congrats! :)
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