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Ambient recording in small theatre.. mic hints?

Hello all,

I'm looking to get some ambient recording coverage of a theatre space that I work with.

The space is small (125 persons capacity) and has a low metallic (!) ceiling (approx. 11-16 ft from floor) that slopes upwards away from the stage, parallel to the raked seating area.

I currently have wireless handheld and lavaliere microphones installed in the PA system which I can send out to recording devices. What i need is some sort of ambient coverage of the theatre space to augment the wireless mics.

Many of the seminars and presentations that we schedule are of an informal nature, and we regularly have the audience asking questions of our talent without the use of microphones. It's a part of the culture of the place, and hard to change.

I was thinking of ceiling mounting either: some omnidirectional mics, a PZM stereo mic, boundary mics, or a stereo pair of condensers.

My original idea was to have two condensers mounted centrally to the ceiling in an XY configuration, but my concern here is that the mics might be too near field to pickup the questions without raising the noise-floor to unacceptable levels. And that using shotguns would not give me the coverage i need across the majority of the seated area.

Other options I'm thinking of >

* Mounting two boundary mics to the ceiling.. something like this Crown PCC160

* Using a stereo PZM mic like the Crown SASS-P MKII

Any thoughts?
All I am looking for is 'clear - audible' coverage with a minimum amount of additional inputs to the mixer/recorder. The recordings will likely be for podcasts and downloadable lectures, not for music production.


keenast Thu, 02/01/2007 - 09:32
You're looking for 'clear-audible' coverage that will be used for podcasts or downloadable lectures. In other words, at least in my understanding, your material will be more or less heavily compressed.

A few thing that come to (my) mind: why thinking of 'stereo' at all when chances are it'll all end up in low resolution mono?

Why trying to record 'ambiance' when what you want is 'clear-audible'. Your additional ambiance will make compression work harder and essentiall work against 'clear-audible'.

What I would do: wire all persons on stage with lavaliers respectively have them use wireless handheld mics and have one (two?) boom operators covering audience (questions). This way you will get excellent intelligible audio that will translate nicely for your intendend purposes.

It will need one (dpending on the real situation maybe two) persons handling audience microphones.

good luck,

Karl Lohninger

Los Angeles

RemyRAD Thu, 02/01/2007 - 15:54
Having been in the business a longtime and doing all sorts of stuff, I'm a little confused about what kind of production you are speaking of? Is this a performance oriented production or is it a town hall meeting?? There is a difference you know?

In the land of broadcasting, news audio, church audio and such, presenters DO NOT NEED AMBIENCE! They need a tight, present, intimate and intelligible sound, without echoes and too much ambience, so the audio guy is always controlling their microphones. The microphones to cover the audience for their questions, should be placed on stands, in the aisles and the audience should be instructed to come forward to their microphones to ask their questions. Conversely, a wireless handheld can also be passed around for the audience questions. If that's not an option, I certainly would not use the boundary nor PZM style microphones and certainly, not on the ceiling. I use those kinds of microphones in that kind of setup, like you mentioned, just for ambient crowd noise and applause, precisely so I can't hear people's conversations.

I would most definitely use either a pair of shotguns pointing towards the audience, if they have to be fixed positions but, most hopefully with boom operators and if that's not available, dynamic microphones such as the SM57. Why do I recommend the SM57 over a condenser microphone, if shotgun condenser microphones are not available?? Because of the slightly reduced bandwidth nature of the dynamic microphones. You will not pick up as much room rumble nor HVAC air handling systems. But like a good broadcast news audio person, you have to ride the level constantly, on any of the audience microphones, which are kept down, or low, until the presenter says "we now have time for some questions". Since leaving them up will provide you with not only too much ambience and that totally hollow room sound, along with the "kick back" from the presenters microphone going through the PA system, it will just sound like you are in a cavern. Not very professional sounding and sound professionals never do that.

I also think you would not want to use compression? Since compression will bring up all of the ambient noise, making for a noisy and uncomfortable listening experience. What you really want, is a limiter. It's very difficult to have random people who are asking questions. Some are loud and eat the microphones, while others stand 6 feet back and whisper. Compressors don't fix that. Audio engineers do, by mixing the event.

There is no simple hands off way to obtain a reasonable recording without somebody actually engineering, unless you want something that sounds GOD awful. There is no magic pill. There is no magic microphone (well, there is one made by RONCO for $14.95 and it really really works. But you have to call within the next 60 seconds). There is no magic mixer.

I like magic marijuana best, while I'm mixing a show!
Ms. Remy Ann David
Yeah man

Pro Audio Guest Thu, 02/15/2007 - 16:50
Hi all

thanks very much for your responses! it has been most beneficial...
some comments and clarifications as follows >

Having been in the business a longtime and doing all sorts of stuff, I'm a little confused about what kind of production you are speaking of? Is this a performance oriented production or is it a town hall meeting?? There is a difference you know?

Think of it as a town hall meeting javascript:emoticon :) in a small town hall.

The events we're primarily wanting to cover are presentations to up to 100 attendees. Many of these presentations are what I would call 'informal' where really interesting content and ideas converge in a space where people are eating their lunch and speaking accapella, interrupting the presenter etc.. chaotic and organic... how perfect for recording!

90% of the time there is only one A/V tech staffing these events. That person is running the mixing desk (live + recorded), lighting desk, switching video feeds through to projector, and dealing with any needs of the presenter.... aaargh! not enough bodies to have somebody supervise the recordings.

We don't have the luxury of boom operators, nor a dedicated Audio Tech for the recording process most of the time. So my conundrum is that I want to capture some audio worth keeping, but I don't have the luxury of having somebody mediate the presentations and direct Q&A via h/h wireless microphones. This is the reality that I am trying to accomodate....

Technically speaking: We do have wireless Lavaliere/Handheld mics, and when we can staff it appropriately I would ride the faders on these signals, but i'm worried about the other instances when I am without adequate staffing.

My current thinking based on all of your super constructive feedback is that I steer clear of PZM mics - and purchase a pair of Avenson STO Omni's that I can install at about 2' off the ceiling [ceiling height is raked between 14-18']. Place them in positions where they pickup any ambient and amplified signals equally. So when somebody wants to come into the space and record without me [which is going to happen a lot] they just take a send out of the desk of these two mics.

I did some tests with PZM mics and a SHURE VP88, both were mounted to the ceiling, and the vibration of the AC system translated into both recordings... about 60-50hz to my ears.

I'm thinking if I get the STO omni's and mount them in shockmounts that some of the vibrations might be reduced. I'm also thinking about installing some kind of rubber stoppers between the mic mountpoints and the stands.

A few thing that come to (my) mind: why thinking of 'stereo' at all when chances are it'll all end up in low resolution mono?

Yes its highly likely most of this will be bounced to mono, so I may position the 2 mics front/back instead of left/right.

Any thoughts or comments would be greatly appreciated!

Many Thanks

RemyRAD Thu, 02/15/2007 - 22:29
Recording spoken word and questions from hanging microphones 14 feet up is going to sound truly horrible. In your situation, PZM's or Boundary microphones should be placed on tabletops, where your moderators or speakers will be. Trying to pick up random questions from a crowd should probably be covered with some short shotguns mounted on stands aimed toward the crowd and not omnis, with the bass cut filter switch engaged.

Shure makes some town hall style automatic mike mixers that provide automatic mixing but are purely useless for ambient microphones. It works on the principle of whoever is speaking into a microphone, has priority. So it would be a fine addition for your presenters microphones patched into your console that will have the ambient microphones always up. Certainly not ideal but what choice do you have? You'll also want some limiting and/or compression, even though that will raise background noise, it will also raise everything to improve the intelligibility of any questions coming from the crowd.

HVAC and other low-frequency noise is easily eliminated by high pass filters. Plus, the issue of Fidelity for spoken word recordings is misnomer. It is intelligibility that you want and so you need some bandwidth limiting since nothing in the extreme high or low frequencies is required for spoken Word intelligibility.

When you don't have an operator, it's potluck.

My mixes are always lucky with pot!
Ms. Remy Ann David

Cucco Wed, 01/31/2007 - 12:19
Personally, I would suggest to NOT use the SASS-P or other similar contraptions.

If you'd like to capture the sounds on the stage and off the stage discretely (seperately, not hidden), a pair of directional mics in ORTF augmented by some omnis further back would suffice.

You will definitely have noise floor issues but I think this is to be expected in a live, open-forum type session.

I'm doing some experimentation with the Rode NT4 right now and I must admit, for what it is and the price, I'm quite impressed. Perhaps it would be a good main pair microphone with a couple Avenson STOs flanking in the rear. (Avensons aren't particularly quiet, but they are quite natural sounding, so any induced electrical noise sounds quite acceptable.)

Cheers -