Recording the Audience, January 1999TIPS ON MICROPHONE SELECTION AND POSITIONING, OR HOW TO AIM SHOTGUNS AT PEOPLE AND GET A GOOD RESPONSE 5/17/2004 8:00 AM Eastern
Behind many hit records is the sound of an enthusiastic live audience. Peter Frampton's "Show Me the Way" and Lynyrd Skynyrd's "Freebird" would not be the same without the sound of a huge and involved crowd. However, exciting audience sounds don't just appear on the soundtrack by accident; it takes planning and a knowledge of audience miking setups to create the impression that listeners are truly part of a live musical event. Going into a recording or broadcasting session, the engineer must have a good idea of what background audience effects he or she wants. After 25 years of recording, I am still amazed by the constant challenges that I find in miking audiences for live broadcasts and recordings. This article describes some of the microphones and techniques I have found to be successful.
To start, let's look at the types of microphones most suitable for audience miking. I typically select shotgun mics as a first choice, though I also use cardioid and omnidirectional mics in certain situations. Among shotguns, the AKG CK69-ULS is my current favorite for getting quality audience recordings, though I have also used this mic in other applications and regard it as a valuable all-around recording tool. The CK69-ULS shotgun element mates with the C480B body, which means it's adaptable to a number of capsules manufactured by AKG including the ever-popular CK-1 cardioid capsule. Also, the CK69-ULS capsule has two parts, and the mic may be set up as either a long or a short shotgun.
The AKG C647 is a small shotgun-looking hypercardioid microphone designed primarily for podium use, but it also makes a terrific audience microphone. It features a flexible gooseneck, is lightweight and is very easy to clip onto just about anything. Further, the price is right, and the off-axis characteristic is reasonably smooth.
Something to remember about shotgun mics is that the ultra-directional pattern is created through cancellation and addition; multiple signals reach the microphone element via the many slotted ports on the shotgun body. Inevitably, not all frequencies cancel and add ideally, and off-axis response can be very "peaky." A lot of microphones measure out well on paper, and the general specification may look great. But you have to be extremely aware of the off-axis frequency response of your microphones, particularly in live work. A quality microphone with good off-axis rejection will reject a lot more unwanted rear signals, such as the P.A. This is important if you choose to place audience microphones on the stage facing back toward the audience, as I do. Find out what the polar pattern looks like, and if you have an opportunity to test it, do so. Using a microphone with poor off-axis response in live situations can result in undesirable coloration of the overall sound of your mix.
MIC LOCATION AND POSITIONING
My typical audience miking setup includes two microphones, one on either side of the stage, facing the audience. I try to locate them as close to the null of the main loudspeakers as possible. By the null, I mean to the side of any loudspeakers, not the rear where you'll get a fair amount of low-end energy, and not the front, where you have all the horns and high-frequency drivers. Yes, low frequency is omnidirectional; however, typically most of the low end is rolled out of audience pickup mics anyway, so it's not a major issue.
Another possible audience mic position is at the front-of-house mix position where a stereo pair would do nicely, though signal delay relative to the main loudspeakers and any onstage mics will be unavoidable. (The delay can be matched during mixdown, of course, but only if there is a mixdown-not likely for a live radio broadcast-and if the audience tracks are recorded separately.) The room ambience picked up on audience mics, with or without the delay between the stage and at the front-of-house position, can be a very exciting artifact to include in a mix.
PZM microphones, hemispherical pickup pattern, placed on front-side walls work well in some situations. In some venues, the room geometry may be such that neither the band nor the P.A. is sonically "visible" to PZM mics on the front-side walls, so the audience response tracks should sound terrific.
Another setup involves wide-spaced cardioid mics or omnis hung from the ceiling. In low-ceilinged clubs or small venues, short shotgun mics on the ceiling aimed across the top of the audience can provide a more uniform audience blend. I try to group my audience pickup and take in as many individuals as possible in that group. At the right distance, the blend of the group becomes "tight," and the resulting applause is much like the sound of hard, consistent rain on the roof.
However, small clubs with low ceilings can present a particularly tough challenge. You must somehow get a picture of the audience in your stereo spectrum without hot-spotting the one jerk in the front who is muttering something about somebody's dog.
OUTDOOR VENUE MIKING SETUPS
When setting up audience mics at an outdoor venue, there are three main factors to consider. First, where is the audience? Most of the audience is far from the stage front and the typical microphone pickup points. There may be no convenient spot to put the microphones within the audience area. To bring the audience to the microphones, you need to use "long-throw," or shotgun microphones.
Second, how do you want the audience to sound? The final mix should have a stereo spread that is exciting and realistic, yet contains some of the nuances of today's more contemporary styles of mixing. I like to spread the audience across the entire stereo spectrum, from hard left all the way over to hard right, with equal energy in between. To make this work, a minimum of three microphones are needed; I like to use four. I pick four audience zones to do the work for the entire audience and choose the zones on the basis of whether I think they will be "intelligent," will blend well with the rest of the mix and will represent the most responsive portion of the audience.
For picking up sound far out into the audience, I start with AKG's CK69-ULS long shotguns and aim them so that the direct axis of the mic visually "hits" the ground at a distance of 100 to 200 feet. In most outdoor venues there is no back wall to cause reflections, so there is no concern about aiming the microphones too high.
I've found various combinations of smaller AKG mini-shotguns useful for close-up area-specific miking. For example, the AKG C647 and C580 are primarily designed for podium use, but I have found them useful in difficult venues where placement is awkward. They sound particularly good and are cost-effective. I often use the smaller shotguns for the far left and far right zones in the stereo mix, whereas I typically place the long shotguns at the 10 o'clock and 2 o'clock pan positions.
Finally, what is the recording environment? To take a recent example, the annual "Opera in the Park" event draws around 20,000 people to San Francisco's Golden Gate Park, where the San Francisco Opera kicks off its coming season with a day of highlights. From an engineering standpoint, the environment at this particular event is pretty awful. It's cold in the morning, hotter than hell in the afternoon, and the wind blows sporadically all day. Shotguns and wind don't go together well, but good-quality windscreens and a few well placed DIP switches can solve the wind problem. Fortunately, the windscreens supplied with the CK69-ULS shotguns proved very satisfactory. Also, since the CK69-ULS is based on the C480B preamplifier body, there are 70Hz and 150Hz roll-off switches available (slope is more than 12dB per octave). By rolling off at 70 Hz and dropping sensitivity by 10 dB (another onboard DIP switch), I was able to defeat virtually all of the wind noise. This allowed us to leave the microphones open at all times in order to pick up every response that came from the audience.
OTHER PATTERNS, OTHER ROOMS
In a large indoor venue, it may be possible to place audience mics in the "Lincoln boxes" on both sides of the stage. At least 20 to 30 feet away from the audience, this mic position is usually well out of the way of the P.A. mains and ensures minimal "hot-spotting" of individuals. A cardioid mic will offer good off-axis rejection, minimizing the effects of nearby reflective boundaries, and will pick up a wide cross-section of people in front. Now combine this pair of "short throw" cardioids with two shotgun mics aimed farther into the audience. The shotguns will pick up a whole different section of audience, yet they may even share the same mic stands as the cardioids. The two mic positions, left and right, provide four mic inputs for a good stereo sweep across your mix.
Omnidirectional microphones may also be used for audience miking, but be careful-omnis will pick up everything, and the results can be either great or horrible. In general, I use omnis in more ambient spaces, where the sonic characteristics of the room are worth capturing. My favorite omnis are the Earthworks TC30Ks; they are clean, accurate, flat and allow me to tailor the room sound to blend with the direct mix from the stage inputs. However, the nondiscriminatory characteristics of omni mics can leave me at the mercy of just about anything that goes on in the room. With a spontaneous and volatile crowd, omni mics may not be the best choice.
HORSES FOR COURSES
Finally, there are nontechnical factors that will affect your microphone selection and positioning choices. Every one of my projects demands that I give the best I possibly can, and when I am doing exacting work for discerning clients, I tend to use my best precision microphones. On the other hand, it does not make good sense to put out your most valuable assets when you know that stage diving is the rule. For such events, Shure SM57s have been the audience microphones of choice-and they do work well. I have had several pairs of Sennheisers thrown off the stage and immersed in 18 inches of liquid mud (Sennheiser provided great repair and a quick turnaround). I've also had union engineers return microphones to me with fresh wood stage splinters protruding from the grille covers. "I don't know how it happened," they shrug.
If the object of the exercise is to record the room for the sake of the room, then it's anybody's artistic call. If the object is to record audience, to get audience response as part of a musical recording, then the objective is to get a great recording of the performance and allow the audience (in that performance) to add the audience's appreciation, not to add coloration or other distracting artifacts to the performance. Your off-axis coloration, the type of microphones you use, where you place them and what direction, are all going to play a part in a large sonic equation. The laws of physics and good horse sense will always prevail.