Choosing a microphone: the three questions

This leads us to the three issues you need to address before buying a microphone. Note that you have to ask the same questions whether the microphone is wired or wireless, since the issues are identical.

What is the pickup pattern?

First is the pickup pattern, or directionality, of the microphone, which defines which sounds the microphone picks up and which it ignores. At one extreme are the “omni-directional” microphones used in your camcorder that pick up sound equally from all sides of the camcorder. At the other extreme are “uni-directional” microphones that pick up sound from a single direction and shut out all other noises.

For some microphones, like the shotguns we’ve been discussing, the pickup pattern is obvious. Shotgun microphones are designed to ignore ambient sound and are extremely unidirectional. In specification sheets for shotgun microphones, you’ll frequently see terms like cardioid, super-cardioid, or even hyper-cardioid pickup patterns, which designate an increasing exclusion of ambient sound to focus more completely on sound that’s directly in front of the microphone.

Most other microphones come in either omni-directional or cardioid patterns, and you need to be careful to get the right microphone for the intended use. For example, if you’re buying a boundary microphone for use on a lectern where you just want the speaker’s voice picked up, a cardioid pattern is the obvious choice. However, if you’re buying a boundary microphone for a conference room where all participants must be heard, an omni-directional microphone is a better choice.

It’s also critical to know the pickup pattern when using the microphone. For example, if you’re using a hyper-cardioid shotgun microphone to pick up a group discussion, you probably won’t capture speakers at the periphery of the group. Similarly, a handheld microphone with a cardioid pattern will minimize sounds not emanating from directly in front of the top of the microphone.

Does the microphone need power?

The next key issue is whether or not the microphone requires power. As we discussed previously, if the microphone requires power, and your camcorder’s microphone doesn’t offer plug-in power, you’ll have to figure out another way to power the microphone.

Most microphones that need power simply list “Phantom Power Requirements” or something similar on the specification sheet. If not, note that all condenser-type microphones will need power, either from the camcorder or battery. In contrast, dynamic microphones do not need power and can run even if your camcorder doesn’t offer plug-in power, assuming you can plug it into your camera, of course. Which leads to our next essential microphone fact, which is connector type.

What’s the connector type?

Virtually all professional microphones connect via what’s called an “XLRM” connector, or XLR male connector. This means that the three XLR pins are sticking out of the connector and that your cable will need a female connector to attach to the microphone. Birds and bees at eleven.

XLR is the favored technology because it is “balanced,” which means that cables can run long distances without picking up noise for electrical wires and other sources. In contrast, unbalanced cables, like those typically terminated with 3.5mm jacks, pick up noise quite easily, especially as cable lengths grow longer.

For this reason, other than shotgun microphones that mount directly on your camcorder, you’ll very rarely see microphones that connect via 3.5mm plugs. The primary exceptions are wireless microphones like the Sony WCS-999 in Figure 2, which uses a 3.5mm jack to connect to your camcorder. However, since the receiver mounts on your camcorder, the distance traveled over the unbalanced wiring is quite short.

About Jan Ozer

I help companies train new technical hires in streaming media-related positions; I also help companies optimize their codec selections and encoding stacks, and evaluate new encoders and codecs.

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