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The Right Mic for the Job

The Right Mic for the Job

The audio side of video can be intimidating for the newcomer and microphone choice is certainly toward the top of the list.

Every shoot is different and while a single camera can work in just about any situation, microphones have more specific roles. Whether it's recording studio microphones with a sound mixer, or a run-n-gun field shoot with no other sound equipment, One-size-fits-all doesn't apply here. It's easy to get bogged down in all the types of patterns, electrical connections, shapes and sizes. Then you have to decide if microphone A is really worth it to you. If your eyes are blurry from catalogs, spec sheets and online vendors, let us insert a little clarity in your search for the right microphone.

Environments

For just a bit, let's think about the audio recording equipment required for the Discovery Channel's Dirty Jobs. If you've never seen the show, you have to look it up online. Host Mike Rowe and his crew visit a wide variety of locations seeking the dirtiest jobs in America. Waste processing, pig pens, sewage ponds, meat packing, the list of dirty locations numbers in the hundreds. And his audio crew has to be ready for just about anything. In addition, they don't work in a studio, so their audio recording equipment has to be portable and pretty much bullet-proof.

Dirty Jobs isn't shy about showing its crew and equipment, including audio production and voice recording gear. Typically, the host and his guests all wear wireless lapel mics and the audio dude also carries a shotgun mic on a boom pole. This is a simple backup strategy. While either type of microphone could work just fine, there's always extra recording equipment in case something bad happens - which it often does.

Having one or more of everything is great, but we can't all afford that. So it's up to you to make the best choice of microphones, given your typical recording environments. Shooting in a controlled studio situation would be a dream for most of us, but we work with what we're given. An outdoor shoot could take place on a busy street corner or in the middle of 200 acres of pasture. An indoor shoot might be in a glass-walled executive office or a warehouse. You just never know.

Another consideration is how many people will be on camera. Do you always shoot talking heads or is there a possibility of another person in the shot? How do you handle three or more people? What about a dozen folks gathered around a conference table? The good news is that there's a microphone (or microphones) for every scenario. Understanding the strong points and how each type of mic works is a great place to start.

Microphone Speak

You've probably seen several terms used when describing microphones. We're going to break them down into simple categories of directional, non-directional and specialty mics.

Directional microphones pick up sound primarily from one end of the device - sort of a point-and-shoot thing. The most common type of directional mic is called "cardioid" for the upside down heart-shaped pickup pattern. A quick look at the pattern shows that this type of mic favors sound from the front, while still picking up some sound on the sides. Virtually no sound is received at the back of the microphone. This type of pickup pattern helps to reject background noise and accentuate the sounds you want to record, whether that is a voice, music or sound effects.

There are a couple of variants on the cardioid design - specifically, the super-cardioid and hyper-cardioid. Each has a progressively narrower sweet spot while rejecting more sound from the sides of the mic. You'll also notice that as the mics become directionally tighter, they also start to pick up a bit of sound from the rear. The amount is small and shouldn't pose a problem.

The ultimate in directionality is the shotgun microphone. These mics are extremely sensitive toward the front with small bumps of pickup to the side and rear. This means you can either pick up sound from further away or better isolate the sound close up. Because they're so sensitive, they also tend to pick up more handling noise. That's why you'll often see them mounted in some type of shock absorbing device.

Non-directional microphones - also called omnidirectional mics - don't emphasize sound from any direction. In fact, their pickup pattern looks like a ball or sphere around the head of the mic. They're available in hand-held models, but the most common non-directional microphone is a lapel or lavalier mic.

Finally, we come to specialty microphones. There are many variations here, but we'll concentrate on two that a video producer might use from time to time. If you need to cover a large area with a single mic, it's hard to beat a boundary microphone. Boundary mics lay on a flat surface like a wall or floor and pick up sound in a half-sphere pattern. Without getting into a physics lesson, a microphone on or very near a flat surface becomes equally sensitive to all frequencies, 360 degrees around the microphone. This means you'll record anything happening anywhere near the mic.

Another specialty microphone is the bidirectional or figure-8 mic. This mic has a unique dual pickup pattern - much like two omni-directional mics with one on either side of the mic body. One side is out of phase with the other and both patterns are combined into a single connector. There are several audio tricks that can be performed with a mic like this, but a common application is recording two sound sources at the same time. For instance, a voice and an instrument, or a speaker and the audience.

Electrical Ramblings

Of course, microphones are only useful in video if you can attach them to your camera or recorder. Fortunately, there are just a few things to deal with here. First, a microphone is either balanced or unbalanced in its electrical connection. A full discussion is beyond the scope of this article, but it's pretty easy to figure out which is which. Most balanced microphones use a three-pin connector, called an XLR connector. If you look closely, you'll see the pins numbered 1-3 with pin 1 as the ground connection, pin 2 carrying the positive portion of the signal and pin 3 carrying the negative portion. Balanced audio is preferred in the pro audio world because it allows very long cable lengths with little signal loss. This type of connection also naturally rejects radio and electromagnetic interference.

An unbalanced microphone uses only two connections; a ground and the signal. You may see this type of connection on mics designed specifically for consumer and prosumer equipment, since they rarely use balanced audio. Short shotguns, lavalier mics and even wireless mics could have a simple unbalanced audio connection. Normally, these microphones use an 1/8-inch connector. Unbalanced microphones have limited cable lengths and may pick up more electronic noise than balanced models.

Application Notes

Now that you know how they work, it should be easier to choose a microphone based on your shooting application. For instance, many news reporters use handheld cardioid mics while reporting on camera. It's a fast and easy way to get decent sound. If your video needs that sort of immediacy or just the look of news, you can't go wrong with a handheld cardioid, super or hyper-cardioid microphone.

Sit-down interviews are often done with omni-directional lavalier microphones. This gets the mic close to the talent and the non-directional nature helps minimize volume changes as the talent moves his or her head. It's also the mic of choice in public meetings like a church service or seminar, although omni-directional headset mics have become popular in recent years too.

If you're shooting a concert, play or office meeting, a boundary mic is a great place to start. By placing the mic on the floor or table - central to all the key players - you can be confident that you'll pick up everything you need. It provides a more open and slightly distant sound when compared to other mic types, but you can compensate with post processing.

For those just starting out, or needing one mic to do it all, choose a shotgun mic. A nice one will be more expensive than some of your other options, but this microphone type is a workhorse. It can be used overhead for interviews and small groups, as a handheld mic, and for other utility recording like sound effects and voice overs. Whether stand or boom pole mounted, a shotgun mic is hard to beat.

Wrapping Up

For the video creator, the right microphone is a key investment in your audio production equipment. It's something you'll take on every shoot and use as often - or more often - than your camera. Picking the right one for your production style gives you the power and flexibility to bring home excellent audio every time, regardless of the location or other circumstances. Choose wisely.

Sidebar: Pick A Mic...

...any mic. Now, pick two or three more similar mics from different manufacturers. When you hook them up and listen to their output, each will sound different. One mic might be crisp and clean while another is muddy and dark. One mic might be a little thin sounding while another booms with bass. Regardless of pickup pattern, no two mics sound alike and you're going to have to decide which one works best for you and your production style. Before you make a purchase, try to audition several models. This may mean borrowing from friends or visiting a local store, just let your ears be your guide.

Contributing Editor Hal Robertson is a digital media producer, photographer and technology consultant.

Tags:  March 2012
Hal
Robertson
Thu, 03/01/2012 - 12:00am