Dollar Store Parabolic Mic

This is a ridiculously easy way to build a very functional parabolic microphone using mostly items purchased from one of those stores where everything is a dollar. Check out the original design at: .Dollar Store Parabolic Microphone

Step 1: Gathering your materials.

First, gather all the materials you will need. This is very easy. In fact, this whole project is so easy you almost don't even have to have the instructable.

Find a small folding umbrella hat, a regular nine inch paint roller handle, and small microphone. Make sure the umbrella hat is vinyl and not fabric. Fabric is too acoustically transparent and will not reflect the sound properly. Just about any small microphone will do as long as it is reasonably sensitive. Here I am using a stereo "Clip-On" mic from Radio Shack (33-3028).

You will also need a few tools and supplies. This is basic stuff. Get a hammer, side cutter, sharp knife, razor saw, permanent marker, some gaffer's tape, and a few cable ties. The reamer is optional. A file might come in handy. So might a small laser pointer of some sort.

That's it!

A little note for "dollar store purists:"

It is possible to build this whole thing using only components from the dollar store. Many of them sell small earbud headphones that can function like microphones, albeit very poor ones. The also sell little hands-free headsets for cell phones. Those have real microphones in them. They will require a little surgery to work but a dollar store purist won't mind. Using either of these options will give you a true $3 parabolic mic

Comments

[Infomasters]

Thanks for the useful feedback.

[Infomasters]

I hooked up a headset with boom mic to my Sony ICD-B600 recorder. Tests fine for recording from the mic and for listening back through the headphones. But I can't hear in the headphones until after the event. What I need is to hear live, as it happens, not on playback from recording. Any ideas for that?

[jurtle]

I don't know that particular recorder but I assume it is one of Sony's small voice recorders. Many such recorders do not allow monitoring while recording so as to avoid any possibility of feedback. Unless your recorder has a live playback option, you may be out of luck. You might try splitting the mic output and running one leg into a small headphone amp but that is another piece of gear in the mix. I have a small Olympus voice recorder that does allow real time monitoring. Maybe a different recorder for you?

[Falconldo]

Great idea, and sparked some great NFO in the discussion.

I found many hats on Amazon:

http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=umberella+hat

if that link doesn't work, here is a tiny URL to the same spot:

http://tinyurl.com/blvfud8

There are many that are Amazon Prime eligible... which means you get it in two days and no charge for shipping. IMHO, Prime is worth the yearly fee for that reason alone (it has changed the way I shop forever), but there are many other benefits. If someone you know (Dad) has prime, they may not know that they can put 3 other members on there account and get most of the perks.

Again, I love it!

[jurtle]

Thanks for the tip about finding hats online. Most of those I have looked at are made of nylon, not vinyl, so they are more acoustically transparent and not as effective as parabolic reflectors. That said, the nylon hats do work but with some slightly diminished performance. I have not done this but I think that a coating of clear varnish or some other kind of sealant might make all the difference.

[integrator]

I wonder if I could figure out a way to make small whisper dishes, like you see at science centers and such? Two of them pointed at each other, you stand in front of them and talk into them, and the reflected sound is heard at the other one 50 or 100 feet away. If it's to small, you may block it though.

[HomeProject]

I first saw two such dishes at the Exploratorium science museum in San Francisco, CA, in the early eighties. Each dish was about 6 feet in diameter. The effect was astonishing. Twenty-five years later I visited the old Roman city of Jerash in Jordan. The outdoor theater there is still in use today. Find a picture if you can. The horse-shoe shaped wall that encloses the "floor" area in front of the stage is carved all around with mini dishes that are about two feet in diameter and no more than about 6 inches deep, if I recall correctly. They work perfectly to transmit and amplify sound across the floor--at least 50 feet. According to our guide, they were used in Roman times as a novel way of trading gossip during performance events. This model suggest your idea could work. Good luck.

[jurtle]

All of the whisper dishes I have seen are fairly large, usually four feet or larger in diameter. They are passive devices and fixed in location. They tend to work better if the participants in conversation have their backs to each other. In general, the larger the dish, the larger the gain. Once you start getting into the smaller sizes, you will encounter the problem of less gain compounded by the acoustic "shadows" cast by the heads of the participants. If you built two active devices such as the one in this instructable, you could achieve the same effect, except that the communication would be electronically amplified (as well as reflectively amplified through the parabola). Simply have the two participants point their respective devices toward each other and chatter away. Unlike the ordinary whisper dish sets, these would not be fixed in location. and the participants would be facing each other.

Good luck with your experiments.

[clibanarius]

So if you happened to have access to a shotgun mike, could you improve its performance by fitting it into one of these babies? I don't actually have a shotgun mike yet, so I'm not sure whether or not the two gadgets are compatible.

[jurtle]

No real advantage to be gained by pairing the two. They work in different ways. Shotguns actually work by excluding off axis sounds. They are directional because of that. Parabolics gather sound from a larger area (so to speak) and focus it toward a more or less single point. They are directional but for different reasons. You would be better off deciding which technology you wanted to use then try to optimize that one.

[bigskyjack]

i like ur style! i made my own parabolic mic a while bak from 1 of those clip-lites for keeping chicks warm, just took out the bulb socket & replaced with a cork with a hole (chem lab style), ran a wooden dowel thru for the mic boom. for the tuning of the mic placement, i found i needed a distant, constant, 'white-noise' source, so i stuck a small transistor radio tuned between stations out the other side of the yard - worked perfectly - & ur rite, the human ear is by far the best sensor for that 'sweet spot' for the mic!

[jurtle]

Thanks. I am glad the project resonated with you. I guess it is clear that I had a ball doing it and even more fun interacting with others who like the project.

[KingOfCatfish]

I love this Instructable!
So you know those really crinkly emergency blankets that resemble foil? Would lining the inside of the umbrella (using spray adhesive or the like) with that help provide better sound? My reasoning with this thought was that the metal-like surface would reflect sound waves better than just the vinyl.

[jurtle]

Glad you like the Instructable. It was fun to put together. As for lining the umbrella with the rescue blankets, I think you would get only marginal improvement if any at all. Those blankets are usually made of mylar, another plastic-like material. Adding another really thin layer of plastic (and glue) to the umbrella might make the whole thing slightly more rigid, thus making it slightly more reflective. My guess is that one would hardly be able to tell the difference in an A-B test. Don't confuse the shiny, almost mirror-like, look of the mylar with good acoustic reflectivity. It will make a much better reflector of light but not of sound.

[KingOfCatfish]

Thank you for getting back to me. My eyes have now been opened, ha-ha. So I was looking at some pieces of Lexan that are at my house from another project and was wondering is forming it into a parabola would work. What do you think the outcome would be?

[jurtle]

I assume you are talking about flat pieces of lexan. Yes, you can fabricate a parabolic reflector from that material. It will require some cutting and gluing. Here is a link that will get you started: http://vzone.virgin.net/ljmayes.mal/var/parabola.htm Otherwise, just do a google search for something like "Make a parabolic reflector." Lots of idea out there. Good luck.

[scraggy12]

Hey , can I use an old direct tv dish?

[jurtle]

Yes, but because the dish is so shallow, the focal point is farther away from the surface. It will work but you won't get as much gain. See an earlier comment/reply on this subject. Good luck

[jacko622]

Could you use a regular umbrella for this? 

[jurtle]

There is a major difference in the configuration of the hat and a regular umbrella. In the case of the regular umbrella, there is the center shaft to contend with. Perhaps instead of removing it, one could re engineer it to be the on-axis mic support. That way you have a support for the ribs and a support for the mic. Then it would be a matter of configuring a handle for the device. Here is where your own builder/hacker/engineer self comes into play. Go for it.

[dakellymon]

 Well done. Great idea.

[wingo395]

Oh one more thing - You showed in the photos but perhaps it is worth mentioning - you want the microphone element pointed IN to the center of the umbrella, not outwards.  This is to pick up all of the reflected sound bouncing off the surface of the umbrella and to the focal point.

[jurtle]

Good call. I did show the mics facing inward in the photos but nothing is said about it in the text. I will probably amend to make the addition. Thanks for the input.

[jurtle]

I have amended the text to point out that the mic should face inward toward the umbrella. Thanks for the input.

[pyro ray]

Ok for those of you interested I found umbrella hats online for like 2.99 ea at a lot of places, from But they are made out of nylon. But you can also take a can of spray paint to the unbrella to close the "pores " of the nylon

[jurtle]

I have not tried that approach but I do think it would work. Anything you can do to reduce the acoustic transparency of the nylon fabric will help. That said, you can still get some detectable isolation of the sound source, even with an untreated nylon umbrella. You might be surprised.

[ilpug]

 use metallic spraypaint to boost the reflectivity of the umbrella... you could even use aluminum foil to line the umbrella. i used a coat of metallic stove black high-heat paint and used a full can... several coats helped alot. i have used these for getting audio on films, and they work great.

[wingo395]

Very nice project!  If you really want to get accurate (as accurate as possible given the flexible nature of the umbrella hat), you can calculate the focal point.  All you need to know is the diameter of the dish and the depth of it.

A simple google search will turn up oodles of info:
http://www.google.com/search?q=calculate+the+focal+point+of+a+parabola

I once bought a parabolic dish (without the mic) from a college, and I bought a very sensitive electret microphone (electets have batteries in them to amplify the signal).  I don't know if it was omni or unidirectional.  My guess is omni might be better, but would need experimentation.  The funny part?  I have yet to put it all together!!

[jurtle]

Glad you liked the project. Yes, one can easily calculate the focal point from diameter and depth in a true parabola. That said, there is no reason to believe the umbrella is actually made to conform to such standards. As I have said in previous posts, the focal point on this device is fuzzy at best. Better to use the methods suggested to get the best result. Much of the physics (and math) that applies to parabolic focus with point sources from infinite distances (therefore parallel rays) just does not apply with variable wavelength sonic sources from variable distances and angles. Too much accuracy is overkill.

[herrdoktor]

 Could you use a large, plastic salad bowl instead of an umbrella?

[jurtle]

Yes. Almost any roughly parabolic surface will work. You just have to find the focus or sweet spot for the dish you are using. Of course, the more accurately it approximates a parabola, the better off you are.

[herrdoktor]

 Thanks, I'll give that a whirl. Have a dollar store down the street, want to try this out with my kids. We live in the country, so hope to capture a number of sounds. Very cool instructable, thanks for posting.

[threedagreexo15]

Hey I'm having some trouble acquiring the vinyl umbrella. Any ideas of where I should look? I tried the dollar store (Dollar General) and few other places and haven't had any success. All i've find is nylon so far.

[tobybirch007]

You could just cover the nylon umbrella with aluminum foil

[jurtle]

Another thought: You might also try looking in a toy store for kids' umbrellas. I think I have seen transparent vinyl umbrellas in places like Toys R Us or Target. Modification of the umbrella would be very different but perhaps worth the effort.

[jurtle]

Sorry you are having trouble finding the vinyl ones. Mine came from a chain called Dollar Tree. I think the items are seasonal so you might have better luck in the coming weeks as the weather warms up (at least in the northern hemisphere). As a last resort you could still use a nylon umbrella if you were willing to coat it some way so as to reduce the acoustic transparency. I think a few coats of shellac would work. The umbrellas are cheap enough to experiment with. Maybe something like Mod Podge, available any hobby or craft store, would work. Good luck with the project.

[threedagreexo15]

Thanks. I just realized that I've been looking at regular umbrellas instead of hats. Is there a major difference between the two? It looks like the regular umbrellas need the rod in the middle in order to hold the rods that hold the umbrella out, so removing that might be difficult.

[jurtle]

There is a major difference in the configuration of the hat and a regular umbrella. In the case of the regular umbrella, there is the center shaft to contend with. Perhaps instead of removing it, one could re engineer it to be the on-axis mic support. That way you have a support for the ribs and a support for the mic. Then it would be a matter of configuring a handle for the device. Here is where your own builder/hacker/engineer self comes into play. Go for it.

[BIGFATSO]

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[BIGFATSO]

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