Boundary Mic's on Tables

[bmdsherman]

I'm running sound for an event tomorrow that involves 6 people sitting at a long table. For the tech rehearsal today I set up 3 boundary mics spaced evenly along the table. I don't remember the exact model number but they looked just like this one:
Audio-Technica U851CW Cardioid Condenser Boundary Microphone, Terminated with 4-Pin Locking Connector (requires power module, included) | Full Compass

The vocals sounded pretty muddy. EQ'ing out the 250-300Hz range a little seemed to improve intelligibility but the microphones still sounded kind of weird.

Does anyone have any quick solutions?

Thanks for your help!

 

[blalew]

no quick solution I'm aware of - I have used lapel mics with an auto mixer (Shure 810) and it worked great. The problem is probably that talkers are being picked up by more than one mic, which will cause comb filtering (sound from one mic "filtering" sound from the other mic). This will be a problem especially when people move around in their chair (sitting back, leaning in, etc). Either give them each short mics on a table stand (SM58) or ... lapels, or make them share 3 wireless HH mics. problem with that is mic technique.

We have Crown PCC-160 (probably similar to what you have) and you could use them with a automixer I suppose, also

Good luck!

 

[museav]

Did you happen to see how it sounded with just one mic or mic channel on?

While they don't provide any detail on the cardioid pattern, the spec sheet for that mic also states "The sound source should not be below, or higher than 60° above, the plane of the mounting surface.", so you might want to look at where the person speaking is in relation to the mic vertically as well as horizontally.

 

[bmdsherman]

The problem is probably that talkers are being picked up by more than one mic, which will cause comb filtering (sound from one mic "filtering" sound from the other mic).

That was my gut reaction at first, but I still had the problem when I muted two of them so that only one was on. My technical director seems to think that it has something to do with the people being 3 feet from a microphone that is suppose to cover an entire stage.

Either give them each short mics on a table stand (SM58) or ... lapels, or make them share 3 wireless HH mics. problem with that is mic technique.

All of our wireless body mics require them to be taped onto the performers cheek and there really isn't enough time to do that, and the people running the show don't want them to have to be passing a round a big dynamic mic.

Do you think the problem could be the mic's picking up the speakers? The table is pretty far upstage (other stuff is happening in front of the table) and I was able to bring up the boundary mic's a lot before I got any kind of ringing.

Thanks again for your help!

 

[bmdsherman]

Did you happen to see how it sounded with just one mic or mic channel on?

Yepp, but I still had problems.

While they don't provide any detail on the cardioid pattern, the spec sheet for that mic also states "The sound source should not be below, or higher than 60° above, the plane of the mounting surface.", so you might want to look at where the person speaking is in relation to the mic vertically as well as horizontally.

Thanks for pointing that out! Horizontally the people are almost dead on because there are only 2 people per mic, but vertically I think they are pretty close to 60 degrees. I'll try to make sure that the microphones are closer to the edge of the table.

Thanks!!!

 

[howlingwolf487]

I think that it's a combination of factors:

1. The size of the surface (boundary) the microphone is situated on.

2. The on-axis/off-axis position of the sound source.

3. The ignorance of the 3:1 Rule of Close-Miking

4. Phasing issues from having too many mics open near the same sound source.

It is also good to brush up on some Boundary/PZM application knowledge (CAUTION: direct PDF download).

 

[blalew]

It sounds like you either need to decide whether the event looks good or sounds good

The PZM on a table isn't the same as a stage floor. If you can't get one mic to sound good, you need to work with placement & EQ until one sounds good. However 2 sq ft is enough to pick up frequencies useful for intelligibility.

You could potentially use the 3 pzms if you could pair people together at the table - 2 per mic. I don't think you mentioned how far the PZM/table arrangement is from the talkers.

A picture or diagram with dimensions may be helpful.

I have to say this isn't a typical use of a PZM - any 'talking head' event typically uses handheld mics, mics on short table stands, podium mics, or lapel mics in combination with an automixer (with varying degrees of expense & inconvenience).

lapel mics (like a Countryman B3) which can be taped to a performer can be used as a lapel mic, but they are typically omnidirectional (& flesh colored) with the pros/cons associated with that. As long as you have a clip it should work if you want to try it. Again, an automixer will be important if your talkers want to talk with any degree of spontaneity.

 

[bmdsherman]

It sounds like you either need to decide whether the event looks good or sounds good

...if only it was up to me

A picture or diagram with dimensions may be helpful.

Again, an automixer will be important if your talkers want to talk with any degree of spontaneity.

It's all scripted so I think I should be okay without one.


Thanks!

 

[blalew]

apologies, this sounds more like theater than what I was thinking - a panel or something like that.

Again, make one sound good, maybe pair the folks together. Good luck & report back if it worked (or didn't) so others can learn!

 

[howlingwolf487]

That picture clarifies things a bit. How did they sound WITHOUT the microphones? Don't let them be lazy and not project just because they're sitting down and using mics...they need to work for their role, darn it!

 

[bmdsherman]

Good luck & report back if it worked (or didn't) so others can learn!

I moved the microphones as close as possible to the downstage edge of the table and that really helped a lot. Since it was all scripted I only had one on at a time but for some reason the center one still sounded funny (maybe because the center people where taller and thus above the 60 degree mark??).

That picture clarifies things a bit. How did they sound WITHOUT the microphones? Don't let them be lazy and not project just because they're sitting down and using mics...they need to work for their role, darn it!

It was an ADL anti-bullying thing and the people at the table where all victims of bullying. It took a lot of gut for most of them to go up there in front of hundreds of people so I really didn't expect them to project well.


Thanks for everyone's help!!!!!!