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.
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.