Gig School
Capturing quality recordings of a live performance
involves factors like mic selection and placement, preamps and good ol'
trial & error
Live recording: the double whammy. The crossroads at which sound reinforcement and getting a good clean signal for recording antagonize and compromise each other.
Whether the job is recording a guest speaker at a convention, a discussion panel (any of whom may talk at any moment), coffee house groups, a theatrical presentation, a church service with choir and band, music group in a small venue, or coliseum rock, the first thing you have to decide is exactly what you want to do with what you record, and how good you want it to sound.
A cheap omni lavalier mic clipped to the talkback microphone gooseneck on your FOH console and a mini disc recorder may be fine for a "quick and dirty" post mortem. One top-level entertainer I know goes a few steps further and uses stereo head mics positioned at various places in the audience so that after a show, he can hear what his audience heard.
In situations like this, you're just looking for that extra perspective, proving or disproving what you thought happened really did happen. You know, that Twilight Zone head-trip in which you think the mix or performance you just did was great, but upon listening to the recording, you hear some not-so-good things you definitely didn't hear during the performance.
A DOSE OF REALITY
The phenomenon cuts both ways. At the end of the night, you're about ready to quit the audio biz and start selling insurance or time-share vacations, because the sound just didn't come together. Upon listening, however, you realize that while not perfect, it wasn't as bad as you thought. Recording live is a great way to add a dose of reality to what you felt was happening during the show.
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It's also a good idea to record every performance, simply to get performers used to the idea that they are being recorded. Recording all the time also increases the chances of capturing those magic moments. However, when recording live for an important purpose, it's a different place with different rules to apply (and break). Maybe you've been only moderately happy with your sound, or perhaps a project requires new microphones to get the desired sound. Likely you've been in a studio and have heard how much better condenser mics capture the high end: brighter and clearer. Dynamic mics are rarely used for cutting vocal tracks in the studio. |
Perhaps you've taken notice of big condenser mics just like the ones in the studio, but costing only $100 - $250. Half a dozen of them in the right places could really improve things, right? Not necessarily.
And while I'm thinking about it...WARNING! Don't ever do mic experiments with a live audience! Only experiment during soundchecks. It's a fact known by most, but I'm simply covering my butt, pointing it out for those to whom this idea may not yet have occurred. The six most important reasons NOT to experiment include the mics, the preamps, the PA, the monitors, the performers and the amps.
ENOUGH DISTORTION
A lot of the cheap condenser mics currently available are very "edgy" and/or "peaky." Don't confuse bright with edge or peak. These new mics may merely sound bright to you at first listen, but over time, you'll hear the distorted edge. Try them on a guitar amp that already has enough distortion to mask the edginess of the mic itself, but keep them away from vocals.
You also have to consider mic sensitivity levels and sound pressure level (SPL) handling capabilities. Some condenser mics can't handle high SPL; either their diaphragms bottom out or the electronics overload, or both. Padding the mic preamp on the console doesn't help if the mic is distorting.
For example, the sensitivity of a Sennheiser 421 dynamic mic is 2 millivolts/Pascal, while a Neumann TLM 103 condenser mic has a much higher sensitivity at 21 millivolts/ Pascal. The SPL rating for the Sennheiser 421 is 175 dB, while for the TLM 103, it's 138 dB at .5 percent distortion.
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Some console preamps will have difficulty with a mic as hot as a TLM 103, which is capable of a dynamic output voltage of 13 dBu, especially when it's jammed up against a cranking guitar amp. So as long as the amp isn't generating over 138 dB SPL, the only level problem might be overloading the mic preamp. Some of the newer, cheaper condenser and dynamic mics have +5 dB peaks or more in the upper ranges of their frequency responses. Also be aware that some may have strange off-axis frequency response and phase response anomalies. Sounds that come in from the sides, like mic sharing vocals, amp and monitor wash can dirty up your mix. Putting these mics on quirky sources with their own peaks is a recipe for pain. |
Some of the best cardioid condenser mics have very generous patterns; much wider than most existing dynamics. This, combined with additional high-frequency response, can cause some really ugly feedback problems, particularly on the "front lines." On the front, the search needs to be narrowed to hypercardioid mics with smooth off-axis response so appropriate gain can be achieved for house, monitors and live recording.
BREAK THE RULES -- TRY AN OMNI
If the backline amps are loud enough, it might be feasible to use an omni condenser mic positioned at the loudspeaker cabinet grille cloth. This approach won't produce the low-frequency proximity hump and density found with a cardioid pattern, so it may be a good idea to rethink your usual equalization (EQ) settings. In all likelihood, there won't be as much mud in the signal as when using an omni.
If heavy EQ is being used to "pull out" the mud, know that using less EQ usually results in a clearer signal, so there could be some added, and audible, improvement. Just make sure the mic is positioned as close to the loudspeaker as possible. (Note: Don't bother trying this on small stages where the amps are crowded together.)
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There are a couple of lesser-known facts about omni mics. They are directional at high frequencies, so the way they're facing matters considerably. In fact, for small groups that don't use PA, as well as for orchestras, very nice stereo recordings can be achieved with a single coincident pair of omni mics (position one on top of the other, with their fronts angled to cover the soundstage). |
The angle is a function of the distance from the sound sources and how widely apart the sources are spaced. The wider the sound stage, the farther back the mics have to be, otherwise they'll be too close to the performers in the center and therefore will be obviously louder in the mix. If the stage is very wide, you may want to try three omni mics in a Decca Tree array.
EAT ME, DON'T EAT ME
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Whether it's a CEO at a teleconference, or a big hair, cod piece-wearing rocker, some performers like to "eat" (get very close to) the mic. This results in sound input to the mic being as loud as it can be. For the CEO that gobbles the podium mic, try a headworn mic like the Countryman E6 - it's small, unobtrusive and almost always at the correct position. With the mic set at about an inch from the talker's mouth, levels are lower and the chance of feedback is lessened. Think twice about using studio condensers for front-line vocal mics. Many cardioid condenser mics have so much proximity effect that the singer or talker can't get any closer than four to six inches before input is too loud. Unless vocalists really understand this and know that even during the excitement of the show they can't eat the mic, it's best not to invite disaster. O BROTHER, ONE OMNI! Recently there's been renewed interest in the use of a single omni or wide cardioid for bluegrass groups as featured in the movie "O Brother Where Art Thou". While it's true that this was a common recording technique during the film's time period (the 1930s), it's highly doubtful that many, if any, of the music tracks for the movie were actually recorded in this manner. |
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With only one mic, it takes a while for vocalists to adjust to how loud their own voices really are, and how to blend together. In addition, vocalists must carefully listen to how loud or soft they (and everyone else) are singing and/or playing instruments. In theory, using one mic means fewer feedback and phase cancellation problems, which should result in a better sound. In practice, performers usually don't get as close to the single mic as they do individually miked. Therefore, the one mic input has to be turned up to a degree where feedback protection diminishes.
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In addition, this application requires a mic with a wider pattern, to help voices and instruments not positioned directly in front of the mic. And, the ability to individually EQ each vocal and instrument is lost. (Talk about a sound mixer's nightmare!)
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Understandably, mixers also don't like losing control of their preamps, but it has been proven that keeping mic-to-preamp cable runs short (generally by locating preamps on stage or just off of it) and using higher-quality preamps found in the "average" console generally improves sound. For added control, remote-controllable preamps can be used, but this feature can drive up cost-per-channel. The bottom line on this issue is to use good mic splitters, shorter cables and quality preamps, and try to locate the recording rig just off stage. Regardless of how you proceed, don't expect to get stellar recordings from one try. |
Sometimes the mix may be good, but the performances aren't. Sometimes the performances are great, but there's a technical problem. The big acts may record every night for an entire tour hoping to capture just a few magical performances. Don't expect your live recording work to be any different, and you won't be disappointed.
Based in Baltimore, LSI Microphone Editor Ty Ford can be reached at tford@livesound.com
January 2003 Live Sound International