On the Air: An Introduction to Broadcast/Voice-Over Microphones
With tons of microphones available, how do you choose the right one? Some are all-purpose; others are meant for vocals and musical instruments; still others are designed for specific applications such as picking up the tones of a harmonica. We'll be focusing here on broadcasting microphones and what makes them ideal for capturing speech. Broadcast mics are widely used in radio studios. They're ideal for voiceovers and announcing.
All of the mics that we'll discuss have a key set of features that they share. The first is a cardioid pickup pattern. A cardioid pickup rejects off-axis noise so that the mic only records your desired sound source, cutting back on other environmental noises. While each mic has a wide frequency response, they are specifically designed to really shine in the human vocal range. Each of the mics also has a shock-mounted capsule, which prevents noise caused by handling and vibration. Integrated pop filters protect the mic capsules from breath pops and sibilance caused by speaking while close to the mic.
Most of the broadcast mics we'll discuss in this article are dynamic, though there are also a couple of condensers. In general, dynamic mics offer some distinct advantages over condensers for vocal applications. The first is power. Dynamic mics do not require any power, while condensers need what's called "phantom power". Because dynamic mics lack active internal electronics, they are much less prone to overloads and distortion. This is helpful for those who speak loudly, since a dynamic mic can typically handle higher volume levels more easily than a condenser. Condenser microphones generally have better performance at higher and lower frequencies than dynamic mics, which allows them to perform well as instrument mics as well as vocal mics.
Another advantage of dynamic mics for broadcasting is that they tend to exhibit much less "proximity effect" than condensers. Proximity effect is a phenomenon that makes audio sound more boomy and bass-heavy when a user gets close to the mic. Dynamic mics also have a greater resistance to ambient noise. This is a distinct advantage in radio and broadcasting studios that often have more unexpected stray and ambient noise than post-production studios. Now that we've covered some of the primary reasons for why a broadcaster might prefer a dynamic mic, let's take a look at the microphones themselves.
One of the oldest and most widely-used broadcasting microphones is the RE20 from Electro-Voice. The RE20 has been in use for over 40 years and shows no signs of slowing down. Remember that picture up above? Do those microphones look familiar? The RE20 is known for its rich low end response, which makes it ideal as a vocal mic. The RE20 features a steel construction for lasting durability. The mic's directional pickup is so effective that the frequency response is almost independent of the angular orientation to the speaker's mouth, providing the ability to move around without creating a noticeable change in vocal tone. The mic features Electro-Voice's Variable-D design, which all but eliminates proximity effect. A switchable high-pass filter allows users to compensate if low frequency rumble or buzz starts to get out of hand. The mic also has a humbucking coil that provides additional protection against hum caused by electrical equipment or bad grounding. For additional protection against plosives, you can use an external pop filter that is specially designed for use with the RE20. The screen Electro-Voice RE20 has 2 adjustable windscreens for enhanced diffusion. Electro-Voice also offers a unique shock mount dedicated to this mic. The RE20 is available as a stand-alone mic, or as a convenient kit that includes the pop filter and shock mount, as well as an articulating boom arm and riser, and an XLR cable.
Similar to the RE20 is the RE27N/D. The RE27N/D includes most of the RE20's key features, including the metal body, Variable-D design, excellent ambient noise rejection, and humbucking coil. Where the RE27N/D differs is that it has a neodymium magnet that improves the mic's sensitivity, frequency response, and SPL handling, resulting in higher gain with up to 6dB more output than the RE20, while still keeping the noise floor low. It also has 3 selectable rolloff filters for tailoring the mic's response.
Next on the list are a couple of offerings from Rode - the Broadcaster and Procaster. These mics have similar designs and features, with the main differences being that the Broadcaster is a large-diaphragm condenser, while the Procaster is dynamic. Each mic has a metal construction and the key set of features we discussed earlier. The Broadcaster has a wider frequency response than the Procaster, giving it more capability for applications beyond vocal pickup. It also has a built-in "On Air" light, letting you know when it's active. Both the Broadcaster and Procaster are excellent vocal mics that can be used for broadcast purposes. The Broadcaster is also available as a kit that includes an external pop filter and an XLR cable.
Our next entry is the Shure SM7B. Shure is no stranger to the microphone game, having some of the most popular dynamic condenser mics on the planet, such as the classic SM57 and SM58. The SM7B is specifically designed for vocal broadcast purposes. It has a large diaphragm that delivers a flat frequency response for true vocal reproduction. It also has switches for bass rolloff and midrange enhancement, letting you tailor the sound to your specific needs. The SM7B is also extremely resistant to electromagnetic hum caused by electronics or bad grounding. The SM7B includes the RK345 and A7WS windscreens for normal and close-up use. The SM7B is available as a stand-alone mic or as a kit that also includes a gooseneck pop filter and an XLR cable.
The last pair of mics we'll look at are from Neumann, one of the world's best-known microphone brands. Their classic U87 is a staple microphone that's a part of many mic cabinets, and is generally looked to as "the" microphone. So it's no surprise that Neumann has some solid offerings in the broadcasting space. The BCM-104 and BCM-705 are similar mics, with the BCM-104 being a condenser and the BCM-705 being dynamic.
Both mics have a very wide frequency response of 20Hz to 20kHz. The BCM-104 has a cardioid pickup pattern, while the BCM-705 has a hypercardioid pickup pattern for even greater off-axis noise rejection. The BCM-104's large condenser capsule provides exceptional vocal clarity thanks to its sensitive design. The capsule and electronics of the mic have been painstakingly crafted to provide a high overload capability with a low self-noise. The result is a condenser that provides clear, rich vocals that bring out all of the nuances in your expression. The BCM-104 also has a switchable high-pass filter for reducing low frequency pickup and a 14dB pad that allows you to increase the mic's headroom when capturing loud vocals.
An especially useful feature on both mics is the interchangeable head grille capability, which makes it easy to remove the grilles for cleaning or switching between users. Additional color-coded grilles are available, allowing you to have specific grilles for particular users. Anyone who has ever used a mic after someone who has been smoking knows that this is a great feature to have for sanitary reasons.
One of the most common accessories that you'll see combined with a broadcasting mic is a boom arm. You've probably seen these if you've ever been in a radio studio or even watched a televised radio broadcast. Unlike mic booms that are used on a movie set or in a music studio, broadcasting boom arms (such as these offerings from O.C. White and Rode) attach to a table and suspend the mic in right front of a speaker's face. This specialized design not only isolates the mic from outside influences that could put unwanted handling or vibration sound on a track, it also provides terrific mobility, allowing the mic to be swiveled in and out of position quickly. There are even specialized multi-arm booms that only have one attachment point to the table, but expand out into 3 arms. This is particularly convenient for recording several speakers without monopolizing valuable table space. Let's visit our first image again. Do you see how a centrally-placed triple boom arm would be ideal in that situation? Each speaker would still have full control over her mic's placement, but they would have more space for their computer monitors and papers.
I hope this breakdown has been helpful for those of you considering a vocal mic for your broadcasting purposes. Feel free to drop by our superstore in NYC to check out our newly redesigned mic room, where you can test a variety of mics and preamps, as well as pick the brains of our knowledgeable staff. Are you already using a broadcast mic that you love, but that we haven't covered here? If so, I'd love to hear about it. I look forward to hearing from you about your adventures (or misadventures!) when rockin' out on a broadcast microphone.