This guide shows how to add an audio input to your megaphone. It's super easy and make your megaphone way more useful.

Why add an audio input?
Megaphones are good for getting noisy, especially at street parties, on bike rides, and at protests. And there's no shortage of reasons to get with your friends and organize a protest. Megaphones are great, but you're limited to amplifying only what you can put into a microphone. What about music?

So with a few minutes of work you can add a new dimension to your protests and critical mass bike rides. You can blast music.

What you'll need:
+ a megaphone (got mine for $10 at harbor frieght)
+ an old pair of earphones (old broken pair)
+ soldering iron and solder
+ electrical tape
+ scissors or knife

Short version:
In this project you'll snip your megaphone's mic wires, snip your earphones, and then solder your earphone jack onto the mic wires.

Step 1: Open Up Your Megaphone

We're going to patch a second wire onto the microphone input, so you're going to need to get into the part of your megaphone where the microphone connects. On my megaphone, I had to take out two screws on the panel above the batteries. Inside you'll find two wires coming from the microphone, usually one red and one black.

Step 2: Snip Some Wires

Cut both the red and black wires that lead to your microphone. Also snip the earphones so you're left with the earphone jack and some hanging wires. You don't need the pieces that go in your ears.

Strip a little bit of the plastic sheathing from each of the four wires: red & black on the mic and two wires that go to the earphone jack. You want to have a little bit of the metal exposed, so you can solder them together.

Sometimes the metal wires inside of earphones are coated in some kind of insulation. You can tell if they are a little colored (red or green, usually). Take a match or lighter to the exposed metal to burn off the insultation. It should burn pretty quickly, like a fuse. You need to do this to make sure the wires make a connection when you solder them together.

Step 3: Connect the Wires

Each of the two earphone wires will likely contain 2 wires: one "live" one and one ground. Since your megaphone is not stereo, you'll want to connect the two "live" wires and the two ground wires. Twist them together.

Next you'll want to connect the jack to the microphone wires. On my megaphone I needed to connect the ground to red and the "live" to black. If that doesn't work for you, switch them. I just tried one and then the other.

Twist the wires together and then either solder them together or wrap them with electrical tape.

I actually got frustrated working with such short wires, so I took a small piece of the earphone wire and soldered it to the mic to extend the wires (see the photos).

Step 4: Patch Up the Case and Close It Up

After you have connected the new wires, add the batteries and test it. If it works, close up your box and you're done. You will likely have to cut a notch somewhere in the case for your wire to come out. I just used a knife to break a little piece of the case off near the latch.

Now your megaphone has an audio input. Hook up an mp3 player and blast some music. The microphone should still work too. You can even sing along to the music while you play it.

Troubleshooting
If you're having trouble getting it to work, make sure your wires are making connections. There isn't much else that could go wrong.

Step 5: Troubleshooting & Future Improvements

There are some neat things that you could do with this. For one, you can easily mount it on a bike with an old bike innertupe. Just wrap it around the outside and tie it to your frame or bike rack.

A cooler improvement would be to get a few of these and add FM recievers in the place of audio jacks. Then use one of those local area FM transmitters that people use in their cars to wirelessly send out music to all the megaphones nearby. It would be neat to have a set of megaphones that are all wirelessly broadcasting the same audio.