Dollar Store Parabolic Mic

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Introduction: 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

Step 2: Let's Prepare the Parabolic Part

The first thing to do is get rid of the hat band part of the umbrella hat. Use the side cutters to snip away the plastic holders.

Step 3: Make a Hole for the Handle

Next, take a look at the very top of the umbrella hat. See that little knob? Slice it off with your razor saw and clean up the hole with a reamer or sharp knife as needed.

Done? Then the parabolic part is almost complete. I told you this was easy.

Step 4: Finish the Parabolic Dish

Now, cut a small triangular piece of the gaffer's tape and place it on the outside of the umbrella hat, near the center. Make a couple of small incisions in the tape and umbrella vinyl to form a cross. This will be the reinforced hole through which the microphone wire will pass.

Step 5: Preparing the Handle

Ok, now let's make the handle. All you have to do is remove the plastic caps and wire frame that hold the paint roller on the handle. Here is where you use the hammer. A couple of good whacks and the job is done. You may have to file away some small burrs on the shaft but otherwise, this step is done!

Is this easy or what?

Step 6: Insert the Handle Into the Umbrella

Now just push the shaft of the paint roller handle through the hole in the top of the umbrella hat so that it protrudes about six inches into the interior. Be careful to leave about half an inch between the bend of the handle and the outer surface of the umbrella.

Once the handle is in place, wrap a piece of gaffer's tape (any kind of tape will do) around the handle and secure it with a cable tie. This will keep the handle from slipping back and mark its position.

Then wrap the inside of the shaft with a piece of tape as well. This will provide a gripping surface for the microphone itself.

Step 7: Install the Microphone

This couldn't be any easier. Just clip the microphone to the shaft and thread the mic cable through the reinforced hole. Secure the cable with a few cable ties to make it neat and you are almost ready to go. Make sure the microphone is facing inward toward the umbrella as shown in the photo below. The idea is to have the microphone pick up the reflected sound from the umbrella, not the direct sound from the target source.

You want to place the microphone as close to the focal point of the parabolic reflector as possible. There are several ways of doing this. First of all remember, this is a plastic umbrella, not a scientifically designed parabola! The focal point is going to be a bit fuzzy, to say the least. So here are a some possibilities from the most complicated to the simplest.

1) Point a laser beam at the umbrella from a distance. You should be able to see where it reflects onto the shaft. Mark that point with a permanent marker (that is why it is in the materials list). Repeat the process several times until you are satisfied that you have identified the general region of focus.

2) Plug the mic cable into a recording device, put on some headphones, point the parabolic mic toward a small sound source (a ticking clock is good), and move the microphone along the shaft until you get the loudest sound.

3)Just take my word for it. Place the mic about three inches, give or take half an inch, from the inside surface of the umbrella. Of course this will vary depending on what kind of umbrella hat you decided to use.

Step 8: Voila! There You Have It!

Add a few cable ties to anchor the mic cable and make it look neater and you are all done.

Step 9: Take It for a Test Ride

Plug your new parabolic mic into the microphone input of your favorite recorder. Use headphones to monitor your work. Then point it at something interesting. You are in for a pleasant surprise. Try recording the same sound without the parabolic set up.

Haven't made one yet? Hey, that's okay. I did it for you. Here is a link to an '''a short MP3 file''' that lets you hear how well it works. First you will hear a recording of a growling squirrel with the mic element by itself followed by the same squirrel recorded with the parabolic set up. That is followed by a similar sequence recording a cardinal chirping in the distance, first without the parabolic setup, then with it. The segments are separated by short tones. I think the differences are pretty amazing.

So, make one for yourself and let me know how it comes out.

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    166 Comments

    I personally would recommend a line level pre-amp.

    I really appreciate your workk

    What part of the instructable leads you to believe it is a study of any kind. I is just and acoustical amplifier. Though it is a great idea and would make a very good one. I am sure that jurtle has no intention of making a scientific study of something that has been studied to death before. Good job on the instructable Jurtle.

    You draw your own conclusion based on whatever you think the "study" you refer to is all about. There is no study as far as I am concerned.

    Uhmmm What is the difference between recording a sound with and without a parabolic microphone?

    1 reply

    Here is a link to an '''a short MP3 file'''
    that lets you hear how well it works. First you will hear a recording
    of a growling squirrel with the mic element by itself followed by the
    same squirrel recorded with the parabolic set up.

    I am not sure what you are asking about. I have not written any research papers about the device.

    Sooo. I tried this with a cloth [lighting reflector] umbrella and there was NO difference in the sound with and without the umbrella.

    I guess I need to find a plastic one.

    1 reply

    The fabric umbrella may be optically opaque but it is acoustically transparent. There is no reflection there. The plastic ones, even if they are optically transparent, are reflective of sound.

    Thanks for the useful feedback.

    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?

    1 reply

    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?

    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!

    1 reply

    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.

    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.

    2 replies

    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.

    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.

    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.

    1 reply

    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.