Shot of videographer holding a DIY parabolic mic dish, standing next to a camcorder on a tripod.

Videographers know that the number one rule of recording high quality sound is to position the microphone as close to the subject as possible. In most scenarios, this means placing the pickup element a few inches from the sound source. We can go to great lengths to maneuver our microphones into the closest possible proximity to our subjects. But sometimes that isn’t an option. There are times when you simply cannot position a mic close to your subject. Enter the parabolic microphone.

Maybe you need to capture the cries of coyotes, or the songs of mockingbirds. Maybe you want to record the cadence of a quarterback (without getting yourself tackled). Or, maybe you need to secure your sound on the sly, like a spy, for your hidden-camera crime stopper show. Sometimes a productions require you to get that mic in close but that can endanger your life, damage your equipment, or blow your cover. A parabolic microphone dish may be the most sound solution around.

Para-what-ic Microphone?

A parabolic dish is a mathematical miracle that gathers and focuses light and sound waves into a single point. They are used in headlights, solar cookers, and satellite TV receivers. The parabolic microphone dish leverages geometry to turn an ordinary microphone into a hyper-directional monster mic. This allows you to recording clear sound at several hundred feet. Unless you produce sports or wildlife video you may only use a parabolic setup on rare occasion.

If you aren’t ready to invest in a professional parabola, you can build your own parabolic microphone dish. This only requires a few simple tools and materials you may already have. Your homemade parabolic dish may not perform quite as well as a professionally manufactured model. This solution will significantly improve your ability to grab sound waves, and may provide all the power you need. Before starting the build, its important to know how a parabolic microphone dish works. 

Parabolic Microphone Science

There is no such thing as a parabolic microphone. When we talk about a parabolic mic, we’re really referring to recording audio with an ordinary microphone that’s boosted by a parabolic dish. A parabola is a specific geometric curve that has a distinct mathematical property. When a straight line hits any point on the inner surface of a parabolic curve it reflects off the slope to a single common point centered in front of the curve. This position is the focal point of the parabola.

In terms of audio, this means that when multiple sound waves from a sound source strike the sloped inner wall of the dish, they bounce back to a focused position in front of the disk. When a barrage of sound waves hit the parabolic dish, the waves are collected together at the focal point. An ordinary microphone in the proper position can capture an amazing analog amplification of the sound source.

Choosing a Microphone

The performance and functionality of a parabolic microphone dish is more about shape and construction than the quality of the microphone itself. However, having a good mic doesn’t hurt.

Wireless microphone transmitter sitting on a table next to the DIY parabolic dish.

Any ordinary mic will work for recording audio from the parabolic dish. There are generally two types of microphones used with a parabolic dish. One option is a microphone with a directional cardioid pickup pattern, like a handheld mic. Another is to use a small microphone, like a lavalier, with an omnidirectional pickup pattern. In either case, the mic is typically mounted on an arm that suspends it at the focal point of the dish. The pickup element faces into the bowl of the parabola. We elected to use the smaller and lighter wireless lavalier mic.

A shot of the DIY parabolic microphone dish with dowel taped cross-length and a milk jug lid sitting on the mic that is attached to the metal support.

Because of it’s omnidirectional pickup pattern, we added a small circular backplate. This will help focus the lavalier on recording the reflected sound source. For recording audio, we connected our wireless lavalier to our video camera’s XLR input. You can use any portable audio recorder if you prefer.

Microphone Position

The key to recording the best audio from your parabolic dish setup is to position the microphone right at the reflected focal point in front of the parabola. The sweet spot varies from dish to dish depending on its depth and diameter. We wanted to test a variety of different dishes. We mounted our lavalier on the arm of a C-stand so we could easily move it around. While listening through headphones we determined the ideal location for each dish. Once you have located the focal point of the parabolic dish, take a measurement, and attach a support arm to use as a permanent mic mount.

Choosing a Parabolic Microphone

The most important part of your parabolic microphone is the dish itself. The parabolic microphone dish does not function like a funnel or megaphone, but as a reflector of sound waves. The size, shape and material of the bowl all influence its reflectivity. Many do-it-yourself designs use umbrellas, frying pans, wok lids and other cooking instruments. You may use any of these to build a parabolic microphone dish that will improve your microphone’s long-distance performance. Some choices are better than others. Generally, you want the dish to have a balance of three properties: a hard surface, large size, and the proper curvature.

The parabolic dish leverages geometry to turn an ordinary mic into a hyper-directional monster capable of recording clear sound at several hundred feet.

Curve:

Because a true parabola is a specific geometric curve, few homemade dishes have full parabolic performance. The trick is to find a dish that closely matches the shape of an actual parabola. If you have access to an old satellite dish, you have an excellent option. While these receivers have an off-axis focal point, they are a functioning parabola. That said, a dish of any shape will work to capture sound waves to a degree. For the best results, select one that has a smoothly curved bottom, not a flat one.

Material:

The ideal material for your parabolic microphone dish will be rigid and thick, but lightweight. Plastic, acrylic and metal dishes are highly reflective. They do not allow sound waves to pass through them, making them more desirable choices. Dishes that have holes, like colanders, are not good reflectors, even if they are shaped well. On careful examination, thin walled metal dishes may introduce a small amount of metallic ping. A dish made of thick plastic or similar material may be the best choice.

Size:

Audio recorded from parabolic microphone dishes tends to have a low frequency response. This is related to the science of sound waves. Small parabolic dishes are simply not capable of recording the full range of sound required for recording audio at full fidelity. However, the science of sound waves suggests that if all other aspects of the dish are identical. A larger parabola could grab the low frequencies. So bigger is actually better. However, the dish is more likely to be impractically large before good low fidelity sound can be recorded in this instance.

The best way to find a dish that meets all three criterion equally well is to buy an actual parabolic dish from a dealer. Professional parabolic dishes are readily available, but they can be costly. If you need a high quality parabolic dish for serious sound production take a look at the JonyShot from JonyJib. ($1,250; microphone not included) It includes a 24-inch dish with handles, a tripod mounting plate, and an isolated microphone mount. As a more affordable option, you can purchase Sound Shark’s SS1 Long Range Dish. This uses a standard lavalier, for $285.

Using the Parabolic Dish

Closeup of videographer wearing headphones.

The only way to know that you are capturing a strong, clear signal is to wear headphones so you can monitor the sound source and make adjustments as you record. Depending on how far you are from the subject, even a small twist of the dish can move the mic off target, so recording requires an active and attentive operator.

Parabolic Microphone Dish Tests

A collection of test devices: popcorn bowl, umbrella, frying pan, parabolic light reflector dish and a trash can lid.

For our project we tested five homespun dish options to determine which would be the best to build:

  • 6” omelet pan
  • 10.5” aluminum shop light shroud
  • 12” plastic popcorn bowl
  • 22” plastic trash can lid
  • 45” golf umbrella

Our tests were performed by playing two different soundtracks, a loop of chirping crickets, and then a music bed, at a distance of approximately 30 feet. We mounted a trusty handheld cardioid microphone and a lavalier to the arm of a C-stand pointing into our dishes while listening through headphones. We recorded samples using each dish, then returned to the edit bay to analyze our findings. While it is difficult to assess comparative quality while you are recording, we noticed a clear difference in frequency response after ingesting the clips into our editing application and playing them back through studio monitors.

Based on our tests, we determined that our 22-inch trash can lid performed the best. Its large diameter, uniform curve and plastic construction all helped push its performance past the other dishes we tested. In this test we also learned where our mic needed to be positioned, so note this during your tests.

The Microphone Build

With our dish selected, it is time to build our DIY parabolic mic. Here’s what you’ll need for the dish which is designed to carry a lavalier mic. We went with this option since it was light and wireless, if we’d gone with the cardioid mic we’d want a shock mount, much like the one for a shotgun mic.

Collection of final parts used for our DIY parabolic microphone dish.

Materials

  • 22” plastic 32gal. trash can lid
  • 6” strip of 1/2” wide flexible metal strap
  • 24” x 1/4” wooden dowel
  • milk jug lid

Tools

  • Metal snips
  • Small hacksaw
  • Gaffer’s tape

In addition to the desirable size and shape of the lid we selected, we discovered that its handles worked perfectly as grips; so there was no need to add handles. We simply needed to build a cross bar and microphone mount.

The Build

First, using the hacksaw, we cut a piece of 1/4-inch dowel that is roughly the diameter of the trash can lid so it would fit snugly into the molded notches on the inside of the handle. We then used gaffer’s tape to hold it in place. The cross bar fell just south of center on our lid, spanning our dish 1 1/ 4-inch off the mid-line.

Closeup of a lav microphone attached to a metal strip, pointing at the inside of the trash can “parabolic dish.”

Next, using metal snips, we cut a 6-inch piece of flexible flat metal strap to serve as our center extension to hold the lavalier microphone. We wrapped one end of the strap around the center of the dowel and secured it with gaffer’s tape. We then shaped it into a slight curve, angling up and out to line up with the center of our dish. At approximately eight inches from its bottom center point when laying on its back, we taped the wireless lavalier’s pickup element to our mount. Securing the cord along the dowel and around the back of the dish with tape, we left plenty of wire for the transmitter to clip onto the operator’s belt. Finally, we attached a 2-inch lid from a milk jug to the back of the mic mount. The will help direct the lavalier’s omnidirectional pickup pattern back into the dish.

The Results

While our research required hours, the build itself took less than 30 minutes. The total cost for the project, minus the trash can lid we had on hand, but including the milk, was less than $25. So give it a try. If you don’t have a garbage can lid to dedicate, use whatever dish you can manage, or spring for a professionally formed parabola. With a little creativity, and some simple science, you’ll be using your homemade parabolic dish microphone in an hour or so.

Sidebar

Parabolic Microphones and Football

The most visible place to see a professional parabolic microphone dish in use is on the sidelines of an NFL or NCAA football game. Just turn on your television on most any weekend in September through January and watch the sidelines for operators holding the cool composite dishes. Though wireless mics are common on the field, until a few years ago, the NCAA used primarily parabolic mics to hear referees. Fox Sports uses six parabolic mics at each NFL game they cover: two on each sideline and one at each of the end zones. Fox Sports chose the Klover MiK 26 parabolic dish ($2,250; microphone sold separately).

Chuck Peters is a 3-time Emmy Award winning writer and producer. He is an independent producer and media consultant.

Chuck Peters
Chuck Peters is a 3-time Emmy award winning writer and producer. He is currently Director of Operation for LifeWay Kids in Nashville, TN.

10 COMMENTS

  1. I did a great deal of research and testing on this exact same subjet a few months back to produce a dish to record my son's water polo games.  My first prototype was a snow disk from big 5 that worked amazingly even though it was not parabolic.

    I found the best make do dish that appeared to be more to the shape of a parabolic is a specific squirrel baffle sold online at a great price  $35.00

    http://www.backyardwildbirds.com/Bird-Feeder-Squirrel-Baffle_p_2835.html

     

    There is also a true parabolic dish sold on ebay but the seller has limited supply. This is the dish I have.

    It is amazing.  Light flexible and a true parabolic.  You can see the focal point by turning your dish toward the sun, for a very short amount of time, and you can see the light focus directly on the tip of the mic if you have placed it at the proper focal length. It will also heat that mic up very fast so make it quick.

    This dish with a sony ecm 55 B omni directional mic is capable  of clearly hearing a person rub their fingers together lightly from 50 feet away on a quiet night.

    http://www.ebay.com/itm/Parabolic-Project-Reflector-Dish-Microphone-Science-Outdoor-Nature-Recording-/331175530326?pt=Educational_Toys_US&hash=item4d1b998f56

    The other thing to keep in mind is the gain.  Your going to need to crank up the gain on your system and if your going directly into a dslr camera, the mic preamps will not give you the clearest audio and probably add a bit of noise, possibly a lot of noise.

    The best thing to do is go into a quality dedicated mic preamp and then into a quality audio recorder. sync it back together later in post.

    Keep in mind that many dslr cameras do not even record at cd bit depth rate for audio  and that will result in less than ideal quality.  My fancy and expensive dslr records audio at a very low bit depth rate of 8 so I use a preamp and the separate recorder.

    Also, note that background noise is the killer.  If you have competing background noise that approaches or exceeds the level of the audio your trying to capture, it will be very difficult to get clean audio.

     

  2. After a great deal of research on this I went with one manufactured by Sound Devices.  They make a few different models, but the cheapest way to go would be their older "Mixpre" model.  It has two balanced xlr inputs for mic input and has batteries or direct power capability.  Look for it used on ebay.  Ballpark 250+  You could then put that directly into your dslr and the quality should  be substantially better than using the gain from the dslr preamps. You will end up turning the gain down all the way on your dslr and might even need to use an attenuating cable to reduce the signal.  Their quality and reputation is excellent. Their mixer preamps are the industry standard for video and film production. The cost goes up quickly from there with any of their other units.

    There are other manufactures but your end use and desired quality will probably determine how much you want to spend.

    A little time spent on audio recording forums will lead to the general consensus that most people who record audio for a living prefer to record at a bit depth rate of at least 24 for audio.  

    My good friend has a very expensive sony professional camera and it captures audio at the cd rate of 16 so you can see why audio is commonly captured separately on a dedicated audio recorder.

    A typical setup would be mic to preamp to dedicated audio recorder, like a Zoom H4n or a fostex fr2le or Roland unit.  All of those will provide you with the high bit rate.  You could put the signal into camera and stand alone recorder at the same time if you wish to help you sync them together later.

    It all depends on what your going to do with it but the setup described will give you a very high quality signal chain.  Use a good mic and you have the ability to capture superb audio.

  3. Sound devices also makes two more basic models called MP1 without Headphone port

    And MM1 with headphone port. Both are battery powered and offer phantom power to your mic.

  4. I found a used DirectTV dish on ebay for $30.  These are parabolic dishes so I am curious why they are not part of any tests or used to make homemade versions?  Just wondering if there is somethign I don't know about them?  I will get mine in a week or so and then be able to make one and test it 🙂

     

  5. In addition to building the parabolic dish and PVC handle, you’ll need to assemble a stereo amplification kit, which requires through-hole soldering skill. This kit is not too difficult for beginners. Read the instructions carefully and use plenty of patience as you solder.

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