Booming inside- Let's talk about it

[Adam Grunseth]

Alright, as I posted previously I'm investing in putting together a budget field audio kit. Things are going good, I'm pretty happy with the kit I'm putting together and the quality is very decent.

However, I'm still searching for a good mic for booming indoors. Every bit of experience I have, and most of the wisdom that has been shared with me, has lead me to the conclusion that your regular shotgun mic isn't ideal for indoor uses. That a small diaphragm condenser is what I want for these situations. Most of the audio guys that I have worked with back this up, and indeed use these kind of mics when using a boom indoors.

To try to figure out what mic I want for indoor booming, I have asked various groups and forums. Apparently, this question is very divisive- Much of the feedback that I am getting is that a shotgun mic is just fine for indoor work. They say if I am getting any kind of adverse audio using a shotgun mic indoors it is because I don't know what I'm doing or because I'm using a Rode mic instead of a Sennheiser. These opinions are coming from people who claim to have decades of broadcast audio recording experience.

So what is the deal? Are shotgun mics just fine for indoor use and anyone who claims different just is doing it all wrong? Or are the people telling me this, guys who've worked in broadcasting for their entire careers, just poorly informed?

Finally, if you were me and budget was a huge factor, what mic would you choose for indoor booming?

[Seth Bloombaum]

Originally Posted by Adam Grunseth

...Much of the feedback that I am getting is that a shotgun mic is just fine for indoor work...

In my experience it's fine to use a shotgun indoors until it isn't.

A lot of this has to do with the size and reflectivity of the room, and the characteristics of the particular microphone.

When it does go bad, there's little that can fix the hollow sound of out-of-phase comb filtering effects in the low-mid to mid range. These are important freq ranges for voice, you can't eq them much, and the comb filtering changes from moment to moment.

Hypercardioid/supercardioid is the usual fix in reflective rooms. Not as directional as a shotgun, of course.

The cinema standard is the http://www.bhphotovideo.com/c/product/377424-REG/Schoeps_CMC641_SET_Colette_Series_Microphone_Set.html.

Budget alternatives include the http://www.bhphotovideo.com/c/product/349107-REG/AKG_Blue_Line_Series_Microphone.html, and http://www.bhphotovideo.com/c/product/642499-REG/Audio_Technica_AT4053B_AT4053b_Hypercardioid_Condenser_Microphone.html.

Ultra budget would be an Oktava MK012 (MC012) with hypercardioid capsule.

But I can certainly understand when somebody says "a shotgun always worked for me". A lot of people with a broadcast background don't know alternatives exist... and are usually working larger rooms, and may be OK with working the mic into the shot.

Anybody with a film/cinema background would be shuddering at the thought. Different markets have different needs and best practices vary.

[Bruce Watson]

Originally Posted by Adam Grunseth

So what is the deal? Are shotgun mics just fine for indoor use and anyone who claims different just is doing it all wrong? Or are the people telling me this, guys who've worked in broadcasting for their entire careers, just poorly informed?

They probably are not poorly informed, but they may have cut corners. That is, rather than giving you the long answer, they gave you the sound bite. Yes, pun intended. ;-)

I'll give you the long answer:

So called shotgun mics are a different design than other mics. They use an interference tube to improve off axis rejection.

The problem with an interference tube is that it doesn't handle quick reflections (that is, reflections from nearby surfaces) well. The interference tube's interference in cases like this often results in comb filtering artifacts. You can easily hear them, and you aren't going to fix them in post, which can make it a disaster.

What makes this a problem isn't that you are using a shotgun mic indoors, it's using it near a surface. So an indoor movie set is just fine, but booming in someones house is problematic. That is, putting the mic 50cm or so from the ceiling (booming) or from a wall, puts you in position to comb filter your dialog.

This works the same outdoors -- if you're near a big concrete wall for example, you're in danger of the same comb filtering. It's not indoors or outdoors, it's rapid reflections from nearby surfaces.

That the problematic near surfaces occur far more often inside is why people typically suggest a hypercardioid for indoor use. And for the record, hypers work just fine outside too.

So... if you aren't capturing sound on a proper sound stage, and if you were you wouldn't likely be posting this question here, then I'd suggest a hyper just to be safe.

Which hyper? The darlings of the indy film makers seem to be the AT4053b, and the Audix SCX1-HC. When I was faced with this choice I found a used 4053 and I've been quite happy with it. That said there are plenty of hypers out there, and they'll all work to some level or other. For booming, you'll want one that doesn't give you a lot of problems with handling noise. Which is probably why the indy crowd seems to gravitate to the above mentioned mics, but I don't know for sure.

[Slavik Boyechko]

I use both the Audio-Technica 4053b and Audix SCX-1/HC. Both are great. Audix is based out of Wilsonville, by the way, so you'd be supporting a local Oregon business.

Cheers -
Slavik

[Jon Fairhurst]

One mic to avoid is the Avantone Pro CK-1. It's cheap and it looks competitive on paper, but the copy that I got was terribly noisy. It might work when mic'ing something VERY close, but for film dialog where the mic is typically a foot or more from the talent, this mic is not acceptable even for consumer applications. A camcorder mic would do a better job.

I've considered opening the mic up to see if I can upgrade the electronics. A simple transistor or op amp replacement might make it great. That said, I have many better projects to complete first. :)

Of course, it's possible that I got a dud. But what would that say about their quality control?

All that said, the box and the mic body were very nice, mechanically.

Oh well, I bought it on a whim to see if it might be a budget winner. It's not. Look elsewhere...

[Rick Reineke]

Best response:
"it's fine to use a shotgun indoors until it isn't"
Another issue is , most of the budget Hypercard mics have a low output which can be a problem with low cost (noisy) recorder's preamps. The AT4053 is very sensitive, around 21mV. The Oktava is 10mV, the Audix is about 17mV

[Jon Fairhurst]

The Avantone quotes 15mV sensitivity, which looks competitive on paper. Regarding noise, they claim S/N Ratio: 1Pa 78dB; Noise Floor:< 17 dBA, which also seems good.

I *wish* my copy met these specs. ;)

[Daniel Epstein]

I have used many mics over the years indoors and outdoors and it is nicer to have the choice of a short shotgun and or Super Cardioid for different situations. Personally for my boom set up I have settled on 416 shotgun and MKH 50 combo. Used to have a Schoeps MK41 as well which was great but had reliability issues which vexed me at the time so I haven't replaced it. My philosophy for field work is the combination of excellent sound and reliability is better than great sound but fragility. As Seth says using a shotgun inside works until it doesn't.

[Richard Crowley]

Please remember that it is about NEAR REFLECTIONS and not necessarily about "INDOOR" vs. "OUTDOOR".

If you were shooting/recording inside the WW2-era blimp hangar at the Naval Air Station at Tillamook , Oregon, while technically "indoors" it might as well be "outdoors" as there is no reflective surface for 100 ft (except the ground). It is still the largest clear-span wooden structure in the world. And similar conditions in the old-school sound stages in Hollywood from nearly 100 years ago.

OTOH, if you were in the middle of Death Valley on a shoot with lots of hard flags providing shade, and hard reflectors changing the direction of the light, you could very well have "indoor" conditions where you have multiple nearby reflections from all the hard-surface grip gear.

[Jon Fairhurst]

There are near reflections and there's also the nature of the ambient sound. Some years ago at NAB, I spent a fair amount of time comparing shotguns. The LVCC is huge (no near reflections), but the crowd murmur is ever present. Even the longest traditional shotgun sounded bad. The reason is that the murmur turns into a muffled, booming mess. Yeah, the off-axis sounds are reduced, but only at the mid and high frequencies. The low frequencies remain. Of course, I could EQ down the lows, but the dialog would sound thin.

On the other hand, the Sanken CS3e sounded great. It uses multiple diaphragms to reduce the off-axis sounds evenly. The murmur was still present, but at a reasonable volume without sounding boomy or unnatural.

So yeah, there's outdoors, indoors with quick reflections, indoors in a larger building, and there's surrounded-by-loud-sounds. Each situation has its own challenges.