Dynamic, condenser, ribbon, handheld, lavalier, shotgun… all are terms commonly bandied about when referencing microphones. One that may not be on the tip of most tongues is parabolic. If “parabolic microphone” has you puzzled, or if you need some guidance for your next parabolic microphone purchase, do read on!
What are Parabolic Microphones?
Whereas dynamic, condenser, and ribbon describe the microphone element or capsule, parabolic refers to something outside the mic: a precision-crafted concave dish that adheres to the properties of a parabola—a mirror-symmetrical curve that reflects incoming parallel beams to a single point. If you’ve ever seen a dish antenna, you’ve seen a parabolic dish. Now, imagine a parabolic dish with a small microphone mounted in the middle of it. Voilà! A parabolic microphone! Since “parabolic” defines the surrounding dish, any microphone properly placed in a parabolic dish is technically (though not optimally) a parabolic microphone. Parabolic mics typically employ miniature or small-diaphragm condensers such as lavalier microphones—rather than dynamic moving-coil or ribbon capsules—due to their smaller form factor, increased sensitivity to sound waves, and lower noise at equal gain settings.
Most microphones are great when placed in proximity to the sound source; some mics pick up everything around them, while others can seemingly focus on objects several feet away. However, only parabolic mics can deliver directional sound pickup at great distances such as hundreds of feet. They effectively amplify low SPLs (sound pressure levels) from long-distance sources while reducing ambient sounds—something that no other type of microphone can achieve regardless of its fancy electronics or accompanying software.
How Do They Work?
Just like antenna dishes focus incoming radio waves to a fixed point of reception, parabolic microphones focus incoming sound waves to a central point of reception. It’s all done through the clever use of a curve. The curve of the parabolic dish must strictly follow a parabola for sound waves to be collected at a single point; dish curves that are too concave, too flat, or too inconsistent will scatter many of the waves away from the microphone. What would that mean for your audio? Distortion, lack of clarity, and reduced level… no one wants that! Thankfully, the folks at Klover make their dishes or “collectors” with parabola curve accuracy to a few thousandths of an inch, so you can trust their dishes to do the deed with ease.
By the way, dish size does make a difference. Larger dishes can reflect and collect more sound waves while providing a larger barrier against ambient sound, yielding longer ranges, stronger signal, and less background/wind noise. So, the larger the dish, the higher the amplification. The dish size also determines the theoretical frequency response. Though all perfect paraboloid dishes yield a 6 db/octave gain increase from low to high frequencies, larger dishes can reflect longer sound waves (a.k.a. lower frequencies). The obvious problems with larger dishes are decreased convenience for portability, more weight for handheld operation, and increased conspicuousness. Applicable to all dish sizes, reflectivity is a relevant factor in determining the output level of the various input frequencies—soft, absorptive dish materials produce less amplification and less low-frequency content.
Once a well-constructed dish directs the sound pressure waves to the central point, it’s up to a microphone to convert the acoustic pressure into electrical signal. The position of a mic in a parabolic dish needs to be level (not angled) and pointing into the closed end of the dish; do not face the mic out of the open part of the dish. Although I mentioned previously that condensers are normally used in parabolic mic setups, a significant variable remains: polar pattern. A microphone’s polar pattern immensely impacts how much of the dish’s reflected signal is “heard” by the mic. Hypercardioid, supercardioid, lobar, and figure-8 should usually be avoided because of their propensity to attenuate or reject signal entering from the sides of the mic—they ignore part of the dish’s amplification. Cardioid responds to SPL from the front and sides (where the dish directs most of the sound), but still reduces signal levels for points beyond 90 degrees and behind the mic, whereas omni picks up sound from all directions. So, cardioid and omni are preferred, yet ideal for different dish depths and sizes. Cardioid tends to be better for shallow dishes, while omni is better suited for deep dishes.
Where are They Used?
Due to the realities of capturing sound with a parabolic dish, parabolic mics do not exhibit the sort of linear, flat frequency response that a measurement condenser mic would; the typical frequency response of a parabolic mic will offer low frequencies that are quieter than the mids and highs. You’ll find parabolic mics ideal for recording long-distance, full-range sources rather than close-up sounds that feature prominent sub-bass. So, sporting events, surveillance, nature documentaries, sound library collections, search and rescue, wedding shoots, and videography are common applications for parabolic mics.
Tell Me More
Klover has an array of parabolic dishes available with or without microphones to serve the needs of many. Those looking for an affordable, pre-configured solution should check out Klover’s Sound Shark ACC Equalized XLR Kit, a mic and 9" dish combo offering a range of about 30 feet. It features a Countryman B3 lav microphone with a windscreen and an XLR connector that incorporates circuitry to equalize the output tone. The Sound Shark can also be purchased as a collector without a mic for users who already have an omnidirectional lavalier mic they like.
Alternatively, if you need something a bit more robust or with longer range, you’ll want to seek out the Klover MiK Series. The Mik 09 has the same dish size and range as the Sound Shark, but offers a dual-clip design for more stable mic positioning, and a dual mounting system for camera shoe or shotgun-style attachment. This collector is designed for omni lav mics, and you’ll need to supply your own.
The Mik 16 steps up to a 16" dish and a range of 250 feet while working with cardioid or omnidirectional mics of the lav type or pencil-style up to 22mm diameter (mics available separately). Plus, it sports horizontal and vertical handles to allow convenient handheld operation.
The Mik 26 is the largest collector in the Klover line, at 26 inches. Available in standard or tactical (for placement into smaller cases) versions, this 26" dish boasts a range of 500 to 600 feet! It’s intended for use with your own omnidirectional lav or pencil mic, and features left and right handles, a rear handle crossbar, and a neck strap. Hold it up, set it down, or replace the crossbar with a monopod/tripod mount (available separately).
Specialized jobs required specialized tools; when it comes to capturing sources at a great distance, parabolic mics are the answer. Stop by the B&H SuperStore or visit our website to dig deeper, and feel welcome to share your favorite parabolic microphone successes in the Comments box!