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Boom mixed with lav? Or just lav. From John Purcell's Dialogue Editing for Motion Pictures

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Hey all,

I just read John Purcell's book Dialogue Editing for Motion Pictures. I thought it was pretty solid. Good stuff.

However, there was one thing he said that I thought was strange, only because I've heard differently elsewhere. He seemed to say to cut out all off-axis except for the primary microphone you choose. Use only "one track of room tone" at a time.

This seems to indicate that you should eliminate boom mikes altogether if the signal to noise for the scene requires it.

However! I've often heard you're supposed to mix them together for a more realistic representation. Also, isn't this how production mixers create their mixes? By mixing boom and lav?

Later in Purcell's book, he does show a boom on top of a lav for various reasons (mostly rmtone issues, though. Ideally, I think he'd do away with the boom).

The issue is really about two things. One is that boom microphones generally have a much better sound, even when they're far away (though such a sound might not be preferred), and two is that we're not rerecording mixers who have very nice reverb-creating equipment. I haven't really managed to create nice-sounding reverb in Pro Tools. Maybe I need to buy a plugin, or some outside...box thing. The reverb that comes from the boom mike is much nicer. It's got nuance to it. I've read that generating genuine-sounding reverb, like that of real rooms, is a complex process.

How do you guys do it? Work with the boom or throw it out? I personally have found various mixes of boom and lavs to be best...so far.

Sawrab

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I find you can sometimes take the artificial edge off a lav by mixing in some of the boom, especially when the boom is not in an optimum position (like in a wide shot), or if the location is extremely noisy. The lav by itself frequently sounds much too close and "chesty" to me, which is what you would expect.

Adding artificial room reverb can also work, particularly if you try different presets and settings. Revibe Room Modeling and TL Space are two that I've seen work. The convolution reverbs can "theoretically" match certain kinds of room sound, but a lot of their effectiveness boils down to experience and experimentation.

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This is a question I too would like to know more about. I've read a lot about how some mix boom and lav on location in certain situations, and also know a sound editor who sometimes use it. On the other hand, I know other sound editors who rarely ever mix the two, thinking it just sounds bad. My own experience leans a little toward the latter so far.

The pro tools reverbs that come with it are not really made for realism, more as an effect for music. You should look up a good convolution reverb like Altiverb (there are also a few good ones included in Speakerphone, which is a great software). A bit pricey, but worth it if you do moderate amounts of sound editing.

I know there are adapters between vst and rtas, so you can experiment with the many free vst plugins out there in pro tools, but I don't know how well they work.

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This is a question I too would like to know more about. I've read a lot about how some mix boom and lav on location in certain situations, and also know a sound editor who sometimes use it. On the other hand, I know other sound editors who rarely ever mix the two, thinking it just sounds bad. My own experience leans a little toward the latter so far.

From my experience, sometimes a shot/scene is mostly boom with a touch of wire. Sometimes it's a lot of wire with a bit of boom. When it's just a bit of boom, sometimes the boom can hang over the action, loosely, but other times it works better for the boom to aim off of the action. There are a lot of variables: room acoustics, background noise, levels of particular lines of dialogue, physicality and different actor's timbres. I end up using a lot of guesswork, experimentation and trial-and-error. But the key, I think, is that I'm listening to a mono mix at the time and able to see and react to those changing variables. If I send in tracks of ISO wires and close-as-possible boom without mono mixing, it may be fine to post mix them. But if the tracks weren't playing well together on set, Post won't have it any easier with them.

Josh

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When I used to record dialog to a single track Nagra, I would sometimes mix in a little boom mic to an otherwise all lav mix. Using the wonderful EQ on my Sonosax SX, I would tweak the boom mic into a pretty thin sound and still have some air in the higher freqs but avoid most of the phasing issues in the lower and mid stuff. The production mix sound good with that combination.

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My experience editing dialogue in post has taught me that you should boom even if you can't "get on top of" the actor(s). At least play from the camera's perspective and you may be surprised at how great the scene will sound with lav mixed in. I sometimes delay the lav by a few fractions of a frame to help match the timing of the boom, or vise-versa.

If you have a good boom track then lavs aren't necessary. I give priority to a good boom over a good lav.

I haven't had the pleasure of mixing down to a two track comp during production. It's nice for the picture editors to have, but I've only ever done 4 track isos with my 744t until this year with the purchase of my Nomad. It was quite nice to have all iso tracks in the OMF to work with. Usually I have to manually pull in and sync the isos in post audio.

Mark O.

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I think most mixers of dramatic shows (off carts, w/ consoles) would answer "all of the above". They make the best live mix they can using whatever combo of mics works, and then iso everything so remixing is possible later. For bag work we aren't so lucky--it's much harder to make a complex mix work with the equipment used in those rigs, while wearing the gear and moving around. Then the live mix starts to be more of a monitor/scratch thing and the isos become more important (depending on the situation).

philp

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My experience editing dialogue in post has taught me that you should boom even if you can't "get on top of" the actor(s). At least play from the camera's perspective and you may be surprised at how great the scene will sound with lav mixed in.

I think this is very wise advice. I have told my boom ops before, "your boom is going to be up, so get ready," and they'd be skeptical simply because they were so far away from the actors due to camera location and lighting issues. But the boom is still extremely useful for establishing some perspective and room ambience, even if it's not close enough for good dialogue per se. All of it can be worked out, and my philosophy is that I'm working for the director first, but for the sound supervisor (and editor) second. I always, always believe in giving post some options. Hell, there's nothing wrong with a "far away" perspective if the people are small in the frame and it tells the story.

If it's a bag job, I just make on-the-fly adjustments as best I can and run everything to isos when possible. I've been going with a wireless boom for about the last year or so, so at least the delay is the same for them and the lavs, and the phase issue with distance is not that big a deal to me provided one is only mixed in 10-15% with the other.

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If it's a bag job, I just make on-the-fly adjustments as best I can and run everything to isos when possible. I've been going with a wireless boom for about the last year or so, so at least the delay is the same for them and the lavs, and the phase issue with distance is not that big a deal to me provided one is only mixed in 10-15% with the other.

There's a delay with the wireless lavs? I wonder if I've heard it on set and didn't even realize. How much is the delay? Can it be compensated for in Pro Tools? If I just have to nudge them in milliseconds, that wouldn't be so bad.

When I used to record dialog to a single track Nagra, I would sometimes mix in a little boom mic to an otherwise all lav mix. Using the wonderful EQ on my Sonosax SX, I would tweak the boom mic into a pretty thin sound and still have some air in the higher freqs but avoid most of the phasing issues in the lower and mid stuff. The production mix sound good with that combination.

So then it's in the lows and mids that the combing occurs. I'll try to EQ it out when I'm at it next.

Sawrab

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There's a delay with the wireless lavs? I wonder if I've heard it on set and didn't even realize. How much is the delay?

I believe it's 3ms. It's not gigantic, but it could potentially lead to phase issues if you combined wired and wireless mics together. I've since gone to an all wireless 99% of the time, so I can mix boom and lavs as needed. As the Senator says, though, the distance of (say) 6 feet will certainly create phase issues with combined mics under some conditions. But I was talking of just a little combination to minimize the "chestiness" from the lavs.

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If you guys want an example of mixing the wired boom and lav, check out this little trailer where I was the production mixer during August of this year. My friend who cut it used the production mix on the camera I believe. If you listen closely you can hear our teachers lines are a little out of phase along with the argument that takes place outside at night. The rest of the trailer is just mostly the boom with a hint of lav at the most. I had everything ISOed so I'm not to worried about the final mix, and also thanks to Wyatt Tuzo for selling me his old AD 146 board which came in handy on this feature.

http://youtu.be/_i9zYti8UWw

Keenan

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I have to admit that there was some inconsistent goofiness on this matter in the first edition of Dialogue Editing for Motion Pictures, which I am (trying) to sort out in the new edition.

Without going through the reasons (I was probably over-influenced by an unending series of hideously noisy films when I wrote 1ed) I was, indeed, over-dependent, or at least vague, on radios. With luck, the message in 2ed will be:

  • Ask the mixer what s/he wants. Don’t be a nudnik, but get a general sense of mix strategy, preferences, and division of labor.
  • Favor the boom, whenever possible, for all the obvious reasons but don’t write off the radios. Be aware of noise issues with the boom.
  • It’s possible to cross cut between boom and radio, but it can be tricky.
  • There is a place for boom in radio-driven scenes. The opposite is also true. Avoid unnecessary tone build up.
  • “It depends.”
  • Ask the mixer.

Thanks for pointing this out.

John

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John,

What do you mean by, "Avoid unnecessary tone build up?" I admit that I have not read your book all the way through, but I do own a copy.

-Matt

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John,

What do you mean by, "Avoid unnecessary tone build up?" I admit that I have not read your book all the way through, but I do own a copy.

-Matt

Hi Matt,

It's my way of saying that if you can accomplish something (a color, a transition, etc.) with fewer rather than more layers of roomtone, then that's the way to go. The point is to keep noise down, but this litte mantra also helps me to come up with a plan for a scene that is as efficient - as opposed to complex - as possible. Of course, thiis is just my way of doing things.

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John Purcell - great to see you here. Welcome.

-vin

PS:

Would you please include (if not already included) the procedure for using Impulse Responses from the set - recording them as an independent operation, using existing elements for IR (like slate sounds or isolated high transients from the production sound tracks) - to aid the process of integrating ADR into production sound tracks?

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Hi vin,

Thanks for the suggesion. I've considered this before, but I tend to think that it's outside the scope of this book. Also, the second edition is running long, and I have to cut back. But more importantly, there are so many people out there who know far more about this than I do (many on this forum, I suspect) that I feel silly getting into it. However, on a quick search I found many good articles on the subject.

-John

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Hi vin,

Thanks for the suggesion. I've considered this before, but I tend to think that it's outside the scope of this book. Also, the second edition is running long, and I have to cut back. But more importantly, there are so many people out there who know far more about this than I do (many on this forum, I suspect) that I feel silly getting into it. However, on a quick search I found many good articles on the subject.

-John

Okay it's kind of surreal that you're actually responding on the site. Cool, too, though.

I've been sound editing a feature, and I was wondering if I should throw away the boom tracks and try to simulate artificial room reverb, or if I should leave just a little. There's something to it...some interesting sound to leaving the mix in; but being inexperienced, I may just be misguided. Sometimes, I feel like I hear comb filtering when the two microphones are at certain distances, for example.

Yes. Whenever I can use just the boom it always sounds fantastic.

The main issue is really about the rerecording mixer, of which there is none on this project and how they work. Maybe if I could find out what their workflow is, I'd know if they wanted me to leave it as a mix or if they wanted me to just give a lav. I dunno...is there a rerecording mixer...book?

You also say to leave umm...both tracks to let the rerecording mixer decide? Something like that.

I've got the Kindle Edition (needed something I could read on the phone). Read it before in print a long time ago, but you know how it is. Books become much more valuable when you need them months/years later.

EDIT: Actually, reading through your post #14, I realize all this will probably be in your next edition. Never mind.

Sawrab

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Hi Sawrab,

I'm in a crunch, so I can't give you the answer you deserve. Briefly: It's all a combination of communication with the mixer and common sense. Opinions about mics and tracks vary greatly among mixers. The second gig with a mixer is much easier than the first. If you can't get to the mixer, I'd say do whatever makes the most sense and sounds OK. Given the time, almost all mixers prefer choices over no choices, and they universally don't like to be boxed into a corner.

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" Don’t be a nudnik, "

::)

" Ask the mixer what s/he wants. " and " ask the mixer "

meaning the production mixer should ask the post mixer(s)...right?

(it might help clarity if you distinguish amongst PSM's and PPSM's...

great to have you here discussing with us!

" I hear comb filtering when the two microphones are at certain distances, for example. "

yep

" about the rerecording mixer, of which there is none on this project "

in which case, it isn't about the rerecording mixer.

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I've been sound editing a feature, and I was wondering if I should throw away the boom tracks and try to simulate artificial room reverb, or if I should leave just a little.

That was done on some occasions in The King's Speech, but not always. It's impossible to predict in any given situation what will sound work: boom only, lav only, lav mixed a little with boom (or boom mixed a little with lav), lav with a little added 'verb, or ADR. Try it and see. I think making it real and consistent is the hard part. And of course dialogue intelligibility is number one.

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