It doesn’t take a lot of experience to realize how important good clean audio is. And how you acquire that audio is going to have a direct impact on your finished video. Since most cameras have an internal microphone, many novice video producers assume that they don’t need an external mike. However, many problems can crop up if you use the built-in camcorder mike as your sole audio source. Often it is too far away from your subject to get good sound. It can also pick up camera noise, such as the sound of your zoom motor. More often than not, an external mike is essential to get good audio.
There are many different types of microphones, more than we want to get into this month. (For a good review of the various mike types see Mike Types in the August 2000 Sound Track column.) What we are going to focus on in this article are the fundamental differences between wired and wireless mikes. Whether you’re planning to use a stick mike, a boom or a lavalier, you still have to decide if you want to use a wireless mike or a wired mike.
A wired mike, sometimes called a hardwire, is a microphone that is physically connected to the recording source, in most cases your camcorder. A wire runs from the microphone to the recorder, thus the name wired. A wireless mike doesn’t have this direct wire connection. Wireless mikes have two parts, a transmitter and a receiver, in addition to the microphone itself. The transmitter converts the sound from the microphone to a specific radio frequency and broadcasts it to the receiving unit near your recorder. The receiver converts the radio frequency back to a standard wire signal and into your recorder.
Knowing which type of mike to use, and when to use it, is not always an easy task. Many factors go into deciding whether to use a wired or a wireless mike. The best way to approach the problem is to understand the pros and cons of both types and choose accordingly.
There are many good reasons to use a standard wired mike. They are more common than wireless mikes, generally less expensive and are often simpler to use. Depending on the specific type of microphone, you may not need any batteries to drive the signal at all. This is good because any time you rely on a battery, there is the chance that the battery could fail while you’re recording.
Wired mikes connect directly to your camcorder. They don’t transmit the signal, so they have a tendency to get little or no interference, giving you more reliability. When you do have a problem with the signal, it can often be easy to check with a wired mike. The signal path is completely visible, just follow the wire from the camera to the mike. You can usually see where the problem is, such as a loose connection or a frayed section of your cable.
Unfortunately, those same positives, can also be negatives. The fundamental nature of a wired mike, connecting directly to the camera, can be a bad thing. When using a wired mike, your video camera is physically connected to whoever is holding or wearing the microphone. Its not enough for you to know that, your subject needs to be aware of it too. Imagine interviewing someone with a wired lavalier mike. When the interview is over, the interviewee gets up and starts to walk away with the mike still connected. There goes your camcorder, too.
That same wire that gives you more reliability and security can also be a hazard. Someone could very easily trip over it and pull your camera off its tripod. A wired mike can also cause problems with the composition of your shot. The length of the wire limits where you can put your talent, and the wire itself can sometimes be difficult to hide.
The greatest advantage of a wireless mike is its mobility. The wire that connected you to the subject with a wired mike is gone. Your subject has the flexibility to move around more. You can get a shot with more distance between the camera and your talent because there is no wire attaching him to the camcorder.
This freedom can dramatically enhance your creativity. You can let your talent move more, knowing they won’t trip over the mike cable. The limitations of movement and distance that you have with a wired mike are nonexistent when using a wireless mike.
This freedom, however, doesn’t come without a price, both figuratively and literally. Wireless mikes tend to be more expensive, and with good reason. Wireless mikes are more complicated. The signal is converted to a radio frequency, transmitted, received and reconverted back to an audio signal.
Any time you process the audio signal, you risk the chance of noise. Wireless mikes are notorious for picking up miscellaneous radio noise. CB radios, cordless telephones and even other wireless mikes can all cause interference problems. If you’re using more than one wireless mike, it’s important to make sure that they aren’t using the same frequency.
It takes energy to transmit and receive your audio signal. Almost all wireless transmitters are battery operated, and the base receivers can be either AC or battery powered, depending upon specific models. AC base units tend to be more reliable, but require an AC electrical outlet. That may not be possible if you need to use your wireless mike in the middle of a forest. Battery powered receivers give you the most flexibility, allowing you to use your wireless mike anywhere. But because the transmitter uses a battery, you will be constantly checking and changing your batteries. Depending upon how often you use your wireless mike, the cost of batteries can add up.
Making a Choice
Knowing the differences between the two categories of microphones is essential to knowing when to use them. Each shooting situation presents different challenges, knowing which mike to use is a matter of setting priorities. For example, imagine videotaping your son’s piano recital. While the video image is very important to the shot, the audio is critical. You need to hear what he’s playing more than you need to see him move about, or worry about where the mike cable is. When the audio is the primary element, you should always try to use a wired mike. You don’t want to risk not getting good audio because of noise, or a bad battery.
If you’re in a controlled environment, such as a studio, or a blocked off section of your house, try to use a wired mike. Wired mikes in general have fewer things that could go wrong, and if you’re in a controlled environment, you can control the negatives easier. If you need a full length shot of your talent and have problems avoiding the wire, try running it under the carpet or around some creatively located plants or furniture.
If the physical distance between the camera and subject needs to be longer than your audio cable, then it’s time to break out the wireless mike. Say you’ve just bought a new house and want to record a thank you greeting for your family and friends. To get the whole house in frame, your camera probably needs to be across the street. Use the wireless mike. Shooting someone across a creek talking about how high the water rose during last winter’s flood can be a very dramatic shot, but difficult to do without a wireless mike.
Wireless mikes work best when the subject has a large range of movement and mobility is critical. Let’s say your taping your daughter’s softball game and want some first person sounds. Put a wireless mike on her. The occasional interference noise won’t override the visual effect of hearing the sounds of the game from her perspective. This shot would be impossible with a hard wire.
Wireless mikes help integrate the viewer into the environment. Instead of interviewing grandpa about the old days in his living room, take him out to the old homestead, and let him walk around. The environment itself, and grandpa’s interaction with it, becomes a part of the story and what you record will have a deeper impact on the viewer.
No Right Answer
When it comes down to it there really is no right answer on when to use a wireless or wired mike. Each shoot is unique. Your choice will vary depending upon the specific needs of each situation. The flip side is that there is no wrong answer either. Use both types of mikes frequently and see how each works differently.
Like any tool, both wired and wireless mikes have a whole list of advantages and disadvantages. How you acquire your audio will have an impact on the end result. It’s your job as a creative video producer to choose which tool is right for each video you make.