Where to place the boom out of the shot?

Evan Donn · August 23rd, 2009, 04:29 PM

Quote:

Originally Posted by Jon Fairhurst

Yeah, a hidden lav is the way to go when a boom is impractical.

I pretty much recommend that if you can't get/don't have a professional boom operator you just go with a lav as primary and only use the shotgun as backup. You can always mix in a little of the shotgun in post to bring back some of the ambiance of the room (which tends to get lost on a lav) but you'll have a much cleaner & consistent voice from the lav. I recently got a countryman b6 which is so small you can just tape it under a collar or lapel and it'll never show up in the shot.

Allan Black · August 23rd, 2009, 08:15 PM

Beg to differ Evan. In post, using a lav voice in a room then mixing in a shotgun of the same voice will very likely cause severe phasing and room cancellations, rather than add any ambience. I wouldn't try it. In a room use a hypercardioid for voice work, not a shotgun.

Regarding lavs the adage goes, whenever you're able, run a cable.

Cheers.

Paul Cascio · August 23rd, 2009, 08:25 PM

Great thread. I'm curious...I just shot am instructional piece using a lav on one channel and a hyper on the other. Should I mix them, or use only one?

Allan Black · August 23rd, 2009, 08:58 PM

Paul, I'm assuming it was indoors and there was only one voice? If so it's a good idea to multimic to 2 separate tracks especially if you have semi or amateur talent.

They usually can't maintain consistent sounds, and if they have to come back to redo something later, they can sound altogether different.

Without hearing your tracks I'd have to say I'd prefer the hyper BUT BUT BUT! what sounds best to you?

I wouldn't mix the tracks, you might not be able to accurately hear or, no offence, recognise any acoustic problems however small they may be.

Why not try a test and lay up 10secs of each mic then ask for opinions, especially from the talent. Good PR mate and you get experience. BTW I'd go out into the street and ask strangers before I'd ask my wife, she knows more than I do :(

Cheers.

Steve House · August 24th, 2009, 03:57 AM

Quote:

Originally Posted by Paul Cascio

Great thread. I'm curious...I just shot am instructional piece using a lav on one channel and a hyper on the other. Should I mix them, or use only one?

I'd agree will Allan and suggest caution about mixing them. Usually the lav/boom combination is so you have a safety net ... you choose whichever sounds the best and discard the other. The boom mic is quite a bit farther from the speaker's mouth than is the lav. This means the voice arrives at the boom delayed with repect to the lav, 1 millisecond per foot of distance difference. When you try to mix them you can introduce reverb and comb filtering effects due to the phase differences.

Paul Cascio · August 24th, 2009, 05:16 AM

Thanks guys - sound advice. Really.

I'm the talent (and I use that word loosly). I never considered the time delay, even though the hyper is only about 15-18" away from my mouth.

A lav always sounds good to my untrained ear, but I own a hyper, so by golly I want to use it. :)

I did record to seperate track, but was leaning toward mixing until I read your responses. I'll split the tracks and ask the 'public' for their opinion.

Allan Black · August 24th, 2009, 06:29 AM

Paul, if your instructional program requires you to poke your head under a car hood or something similar where you move around, you might find the lav on your chest sounds best.

If it does, use your hyper to record your opening narration over the pix intro. You could end up with 2 voice sounds for the price of one ;) Get in close, smile and pitch your voice down, the punters won't twig.

And it's a good chance to learn more. Put both current mics up on separate tracks in sync with the pix on your NLE. Zoom right into waveform and note how far apart the voice peaks of each mic are.

Theory says the hyper will be after the lav because of its distance from you and that's where you'll get your time delay if you mix 'em together.

Try listening carefully on phones and raise and lower each track against the other. At some point you'll hear that boxy roomy distant sound, that's the phase cancellation problem you want to steer well clear of.

Cheers.

Natan Pakman · August 24th, 2009, 08:04 AM

Allan suggested using a hypercardioid mic for indoor voice work, as opposed to a shotgun. I have never understood the real difference between these terms. Is the shotgun even MORE DIRECTIONAL than the hyper? In any case, I find that product pages tend to refer to many types of cardioid, hypercardioid, and shotgun mics as "shotgun" mics.

I understand that hypercardioid mics have a narrower area of pickup in front, but slightly more rear pickup, when compared to cardioid mics. What is the purpose of having rear pickup?

Jon Fairhurst · August 24th, 2009, 10:39 AM

Natan,

A shotgun strives for a narrow "beam" of well balanced sound. It does this by using an interference pattern from the sides. The rear lobe is an unwanted artifact from this design, but there it is.

Unfortunately, only the high frequencies are very narrow. As the frequencies move lower, the pattern gets wider. In other words, as you move off axis you progressively lose high frequencies. Being an interference pattern, different frequencies cancel at different points as you move off-axis. Rather than falling off smoothly, the frequencies fall off in cascades.

The idea is that we get a natural sound from the talent, and reject as much off axis sound as physically possible. The ideal use is outdoors with the mic pointing straight down. This points the rear lobe at the sky, the front lobe at the talent, and the unwanted sounds at the sides. The unwanted sounds come through with the frequencies all messed up, but hopefully their levels are low, and between the mic's frequency rejections and the physical distance, we won't hear much from them.

The problem with using a shotgun indoors is that we get echos from the talent. They return to the rear and sides of the mic delayed and possibly at a high level. Worst of all they are correlated with the talent's voice. So now you get the talent's delayed voice with frequency distortions. That lobe on the back picks up the reflection from the ceiling strongly. It all serves to screw up the main signal.

A cardioid or hypercardioid doesn't have a strong rear lobe. The falloff of high frequencies as you move off-axis is smooth. The echo will have the high frequencies rolled off, but you don't get such bad phase distortions and comb filter effects. A room might sound a bit boomy, but it won't make the talent's voice sound distorted.

Evan Donn · August 25th, 2009, 04:03 PM

Quote:

Originally Posted by Allan Black

Beg to differ Evan. In post, using a lav voice in a room then mixing in a shotgun of the same voice will very likely cause severe phasing and room cancellations, rather than add any ambience. I wouldn't try it. In a room use a hypercardioid for voice work, not a shotgun.

That's good to know, I haven't encountered any issues yet but I don't end up using the shotgun audio very often. I'll amend my statement then - my main point is simply that without a dedicated, professional audio person I'm confident most people will get noticeably better audio from a lav than a shotgun (or other mic).

Allan Black · August 25th, 2009, 04:39 PM

Quote:

Originally Posted by Evan Donn

That's good to know, I haven't encountered any issues yet but I don't end up using the shotgun audio very often. I'll amend my statement then - my main point is simply that without a dedicated, professional audio person I'm confident most people will get noticeably better audio from a lav than a shotgun (or other mic).

Not being a pro audio person, anyone else is likely to get a different result everytime they go out with either a lav or a shotgun .. until they get experience.

Just moving the lav 3 inches on someones clothing can change the sound drastically.
Anyone in this position needs plenty of setup time to get good results and this eats into shooting time. Starting out that's one of the biggest traps and can drive others beserk.

Cheers.

August 23rd, 2009, 08:15 PM	#17
Allan Black Inner Circle Join Date: Sep 2006 Location: Sydney. Posts: 2,887	Beg to differ Evan. In post, using a lav voice in a room then mixing in a shotgun of the same voice will very likely cause severe phasing and room cancellations, rather than add any ambience. I wouldn't try it. In a room use a hypercardioid for voice work, not a shotgun. Regarding lavs the adage goes, whenever you're able, run a cable. Cheers. __________________ Drink more tap water. On admission at Sydney hospitals more than 5% of day patients are de-hydrated.

August 23rd, 2009, 08:25 PM	#18
Paul Cascio Trustee Join Date: Sep 2004 Location: Bristol, CT (Home of EPSN) Posts: 1,192	Great thread. I'm curious...I just shot am instructional piece using a lav on one channel and a hyper on the other. Should I mix them, or use only one? __________________ Paul Cascio www.pictureframingschool.com

August 23rd, 2009, 08:58 PM	#19
Allan Black Inner Circle Join Date: Sep 2006 Location: Sydney. Posts: 2,887	Paul, I'm assuming it was indoors and there was only one voice? If so it's a good idea to multimic to 2 separate tracks especially if you have semi or amateur talent. They usually can't maintain consistent sounds, and if they have to come back to redo something later, they can sound altogether different. Without hearing your tracks I'd have to say I'd prefer the hyper BUT BUT BUT! what sounds best to you? I wouldn't mix the tracks, you might not be able to accurately hear or, no offence, recognise any acoustic problems however small they may be. Why not try a test and lay up 10secs of each mic then ask for opinions, especially from the talent. Good PR mate and you get experience. BTW I'd go out into the street and ask strangers before I'd ask my wife, she knows more than I do :( Cheers. __________________ Drink more tap water. On admission at Sydney hospitals more than 5% of day patients are de-hydrated.

August 24th, 2009, 05:16 AM	#21
Paul Cascio Trustee Join Date: Sep 2004 Location: Bristol, CT (Home of EPSN) Posts: 1,192	Thanks guys - sound advice. Really. I'm the talent (and I use that word loosly). I never considered the time delay, even though the hyper is only about 15-18" away from my mouth. A lav always sounds good to my untrained ear, but I own a hyper, so by golly I want to use it. :) I did record to seperate track, but was leaning toward mixing until I read your responses. I'll split the tracks and ask the 'public' for their opinion. __________________ Paul Cascio www.pictureframingschool.com

August 24th, 2009, 06:29 AM	#22
Allan Black Inner Circle Join Date: Sep 2006 Location: Sydney. Posts: 2,887	Paul, if your instructional program requires you to poke your head under a car hood or something similar where you move around, you might find the lav on your chest sounds best. If it does, use your hyper to record your opening narration over the pix intro. You could end up with 2 voice sounds for the price of one ;) Get in close, smile and pitch your voice down, the punters won't twig. And it's a good chance to learn more. Put both current mics up on separate tracks in sync with the pix on your NLE. Zoom right into waveform and note how far apart the voice peaks of each mic are. Theory says the hyper will be after the lav because of its distance from you and that's where you'll get your time delay if you mix 'em together. Try listening carefully on phones and raise and lower each track against the other. At some point you'll hear that boxy roomy distant sound, that's the phase cancellation problem you want to steer well clear of. Cheers. __________________ Drink more tap water. On admission at Sydney hospitals more than 5% of day patients are de-hydrated.

August 24th, 2009, 08:04 AM	#23
Natan Pakman Regular Crew Join Date: Feb 2009 Location: Los Angeles, CA Posts: 196	Allan suggested using a hypercardioid mic for indoor voice work, as opposed to a shotgun. I have never understood the real difference between these terms. Is the shotgun even MORE DIRECTIONAL than the hyper? In any case, I find that product pages tend to refer to many types of cardioid, hypercardioid, and shotgun mics as "shotgun" mics. I understand that hypercardioid mics have a narrower area of pickup in front, but slightly more rear pickup, when compared to cardioid mics. What is the purpose of having rear pickup?

August 24th, 2009, 10:39 AM	#24
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Natan, A shotgun strives for a narrow "beam" of well balanced sound. It does this by using an interference pattern from the sides. The rear lobe is an unwanted artifact from this design, but there it is. Unfortunately, only the high frequencies are very narrow. As the frequencies move lower, the pattern gets wider. In other words, as you move off axis you progressively lose high frequencies. Being an interference pattern, different frequencies cancel at different points as you move off-axis. Rather than falling off smoothly, the frequencies fall off in cascades. The idea is that we get a natural sound from the talent, and reject as much off axis sound as physically possible. The ideal use is outdoors with the mic pointing straight down. This points the rear lobe at the sky, the front lobe at the talent, and the unwanted sounds at the sides. The unwanted sounds come through with the frequencies all messed up, but hopefully their levels are low, and between the mic's frequency rejections and the physical distance, we won't hear much from them. The problem with using a shotgun indoors is that we get echos from the talent. They return to the rear and sides of the mic delayed and possibly at a high level. Worst of all they are correlated with the talent's voice. So now you get the talent's delayed voice with frequency distortions. That lobe on the back picks up the reflection from the ceiling strongly. It all serves to screw up the main signal. A cardioid or hypercardioid doesn't have a strong rear lobe. The falloff of high frequencies as you move off-axis is smooth. The echo will have the high frequencies rolled off, but you don't get such bad phase distortions and comb filter effects. A room might sound a bit boomy, but it won't make the talent's voice sound distorted. __________________ Jon Fairhurst