Study Hall


Making A Connection: Deploying Mics To Capture The Sound Of The Room And/Or Audience

Defining the goals for deployment followed by various approaches, placement considerations, helpful advice and more.

Crowd and/or room microphones can be helpful for a broadcast mix or in-ear monitors in better connecting listeners to the rest of the room, whether they’re located miles away or standing on stage. But balancing the ambience of the room, the sound of the house system, and the response of the congregation can be challenging to do, especially if you’re on a budget.

Before selecting mics and placing them, it’s vital to know what you’re wanting them to pick up. If you’re running a broadcast mix from front of house and want to blend in the sound of the room with the direct signal from the console, you might want to pick up some of the direct sound of the main loudspeakers.

But if you only want to hear the response of the congregation and some of the room ambience, then one of your goals is to reject the sound of the main loudspeakers as much as possible.

Getting Started

A straightforward approach to add ambience is to place a pair of cardioid dynamic mics on either side of the front edge of the stage, facing outward. Almost any cardioid dynamic design (think Shure SM57 and 58) can work for this application. While they won’t pick up every detail, it can go a long way in capturing some of the essential ambience and congregational response to remove the disconnected feeling of a dry, crowd-less mix.

Since the mics will likely be relatively close to subwoofers and off-axis to the loudspeakers, rolling up the high-pass filter (HPF) to around 200 Hz can clean up the signal so that it doesn’t feel muddy when mixed in. In addition, supplying a stereo version of this signal to in-ear monitor mixes can give musicians and singers some of the spaciousness they crave. (And hopefully it keeps them from pulling one side of their IEMs out!)

Again, if you’re pulling double-duty and mixing broadcast from FOH, it can be a good idea to place a stereo set of mics at the tech booth and blend in their input with your mix. This can capture the way the room and loudspeakers impact the mix, and when merged with your console’s stereo output, can give a better representation of how you’re hearing the mix to everyone else listening via the broadcast.

However, look out for two things. One, these mics are very likely to pick up the conversations of anyone standing nearby, including you. And two, the signal from the console will arrive sooner than the signal arriving at these mics. Since the speed of sound is about 1130 feet per second (or about 1 ft/ms), the distance from the loudspeakers to the mics will introduce a delay.

If you blend in their input sparingly, the timing difference might not stick out too much, but if you rely on them more heavily, consider delaying the console’s output to match the timing of the signal arriving at the mics. A simple way to find the delay in milliseconds is measuring the distance from the loudspeakers to the mics in feet and multiplying it by 0.88. This should get you close enough. Of course, if you blend them too much and it’s likely to make the mix sound distant and washed out, sort of like a video taken with a phone.

Placement Considerations

If you’re seeking a blend of the crowd, the house, and the room ambience, hanging a pair of condenser mics from the ceiling can help get you there. Consider just how much of the PA is getting into the mics, and, how low you hang them will determine the balance of how much crowd response you’re getting.

But there’s also a good chance that there’s something else that’s probably up high in the ceiling – the HVAC system. Make sure that the mics aren’t getting blown on by the vents or picking up fan noise from the return.

If you would like to attain the most rejection of the PA with the highest proportion of crowd response, shotgun mics are your friend. These super- or hypercardioid microphones have a very narrow polar pattern that gives them a very long throw, so they can pick up sounds from far away while rejecting sounds that are coming from the sides of the mic or off-axis.

Using camera lenses as a comparison, cardioid polar patterns are like a fisheye lens – they work great for things that are up close and they’ll pick up everything on the front side of them. However, these narrow-pattern mics are more like a zoom lens, so they can be farther away and capture a narrower slice of what you’re seeking. Since you likely don’t want to capture the sound of people’s throats in the first row, placing the mics higher up is going to help in capturing a better cross-section of the entire congregation.

“But James,” you ask, “won’t that get the mics closer to the speakers?” Yes, yes it will. But look at the polar pattern of a shotgun mic and you’ll see that it’s very good at rejecting sounds from the sides. So, if we can arrange each microphone so that its least-sensitive directions are pointed toward the loudspeakers, it will result in the least amount of bleed possible. Low frequencies are very difficult to reject, but that’s what the high-pass filter is for.

The directional characteristics of a DPA 4017B shotgun microphone.

The other thing to watch for is the lobe in the back of the mic that picks up sound. This is another reason why it helps to have the mics up high and tilted down so they’re not picking up the noise coming from the stage.

When it comes to pointing the mics, a small difference in angle can make a big difference in where it picks up. Plus, if you’re like me and get a little disoriented when up high on a ladder or scissor lift, it’s hard to tell exactly where the mics are pointing. Using a laser pointer held tight alongside the mic can help you get a better idea of where its center is pointed.

Worth The Effort

I’ll leave you with this final thought: although it’s difficult to compare two or three crowd or room mic setups, it’s worth the extra time, energy, and resources to get these mics in the right place. If you have enough channels and mics, try setting up several pairs and recording each separately on a multitrack recorder to listen back later.

If you only have two mics or channels to work with, invest the extra time it takes to place them – try it for a weekend, then move them and see which setup works better. One thing that sets great audio engineers apart from good ones is that the former is always seeking improvement and stretching for better results, growing in baby steps as time goes on.

The people watching (and listening) over the broadcast and the musicians on stage might not be able to articulate it when it’s just right, but even small changes with broadcast and monitor mixes can help people to feel more connected to one another.

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