How to Choose the Right Microphone For Recording

By Bobby Owsinski

With such a huge variety of microphones currently on the market, it's no wonder that even experienced engineers and musicians sometimes get confused over exactly which mic to use and where to use it when recording. This summery of one of the sections from Chapter 6 of The Recording Engineer's Handbook, 2nd Edition tries to take some of the mystery out of microphone selection.

While it's safe to say that most engineers rely on experience when choosing the perfect microphone for recording, some just pick a mic because they've seen others use it in a similar situation. That method frequently works, but if you use some common sense you'll find that picking the mic that gets the best results is easier than you think.

Here are a number of things to consider before making a selection.

1. Select a microphone that compliments the instrument that you'll be recording. Of all the considerations for mic selection, this is the biggest. As an example, if you have an instrument or an amplifier that has a very edgy top end (meaning that it's a bit bright, like a banjo for instance), you wouldn't want to choose a mic that also has that quality since those frequencies will be emphasized even more. Instead, choose a mic that's a bit more mellow, such as a ribbon. This is one of the reasons that a ribbon mic works so well on brass, for instance.
2. Is the mic designed to be used in the "free-field" or in the "diffuse-field"? Free-field means that the sound source (the instrument) is mainly what the mic hears if pointed in that direction. An example of a free-field mic would be a directional mic with a cardioid-type pattern like a Shure SM-57. Diffuse-field means that the reflections play a large role in what the mic hears, since the mic picks up a lot more than what it's pointed at. In other words, an omni-directional mic like an E/V 635A. Mics designed for free-field use tend to have a very flat frequency response in the high frequencies, and as a result can sound a bit dull when placed further away from the sound source (like 10 feet and beyond). Diffuse-field mics have a boost in the upper frequencies that make them sound flat when placed further away, like the venerable Neumann M50's used for orchestral recording.
3. Select a mic that won't be overloaded by the source. Some mics are easily overloaded by a loud source. You wouldn't want to put a ribbon mic or many condenser models on a snare drum with a heavy hitting drummer, for instance. In the case of the ribbon mic, not only might you overload it, but perhaps damage it as well.
4. Choose the right polar pattern for the job. If leakage is a consideration, then choose a mic with the proper directional capabilities for the job. If a mic has a flat frequency response on-axis (meaning directly in front of it's capsule), it will roll off the highs when it's 90 degrees off-axis. If it's flat 90 degrees off-axis, it will have a rising high end when it's on-axis. If you're in a situation with a lot of leakage, it's better to use a mic that has really good off-axis response so that the leakage sounds good. That way it can be used to your advantage.
5. Is proximity effect an issue? Proximity effect only occurs in a mic with a directional pattern and means that the low frequencies are emphasized as the sound source gets closer to it. If you're close-miking an instrument, will the bass buildup from proximity be too much? If you think it might be, consider using an omni-directional mic instead.

Finally, there are additional microphone considerations to take into account when selecting the perfect mic for the job.

• Condenser microphones of a given polar pattern will tend to give you more room sound than dynamics of the same polar pattern
• Omni-directional mics actually will provide lower frequency response compared to cardioid mics
• Large diaphragm condensers have lower self-noise than small diaphragm condensers
• Small diaphragm condensers are generally less colored off-axis than large diaphragm condensers

Ultimately, your choice really depends on what sounds best in a particular recording situation, so let your ears be your guide. But if you consider the points outlined above, you'll save yourself a lot of time during the selection process. For more info on The Recording Engineer's Handbook 2nd Edition.

A long-time veteran of the music industry, Bobby Owsinski has produced and composed for records, motion pictures and television shows along the way. Currently a principle in the DVD production house Surround Associates and content creator 2B Media, Bobby has also penned hundreds of articles for many popular industry trade publications and has authored several books that are now staples in recording programs in colleges around the world including "The Mixing Engineer's Handbook", "The Recording Engineer's Handbook", "The Audio Mastering Handbook", "The Drum Recording Handbook", and "How To Make Your Band Sound Great". A frequent moderator, panelist and program producer of a variety of industry conferences, Bobby has served as the longtime producer of the annual Surround Music Awards, and is one of the executive producers for the "Guitar Universe" and "Desert Island Music" television programs. Visit Bobby's Blog at http://bobbyowsinski.blogspot.com/