MythBusters BUSTED it, but they were wrong. Here’s how to do it ..
The idea of making a speaker out of a paper plate is intriguing, and to do it for under a buck is even better. But first, I’ll have to understand how a speaker works. I’ve still got these 8 Ohm speakers from a previous video, and I’ll sacrifice this one in the name of discovery. I’ll use a utility knife to cut the cone away from the surround, exposing the basket, as well as this yellow diaphragm known as a spider. I’ll cut through that and snip these 2 wires, and am impressed at how simple a speaker really is. The bottom of the basket is attached to a strong ceramic magnet, with a hole just big enough to allow this voice coil to vibrate in. I’ll use a foam bowl for the basket, an 8.5″ paper plate for the speaker cone, 6 button magnets, and then a piece of printer paper to form my voice coil. This brings my pro-rated cost to about $0.80 for this soon to be speaker. But what about insulated copper wire? That can be expensive, and where do I get it? There has to be some inside this old TV, but I don’t have a sledge hammer to bust it open. So I’m going to have to get creative. Ok, I’m down to the circuit boards, and there’s the piece I’m after. A small audio transformer. These things are packed tight with the perfect wire for this project. I’ll use my pipe wrench pliers to rip that off the board, then use my bench vise to crack the ceramic casing off. I’ll peel off the insulating tape, and presto, I’ve got a nice roll of insulated copper wire .. for free! I’m ready to start building, and I’ll make the voice coil first. I’ll start by cutting a few strips of paper and rolling them around my stack of magnets. I’ll wrap the wire about 50 times and then use some hot glue to keep it in place. When that’s dry, I can pull the magnets and the inside layers of paper out, leaving just this shell. The voice coil is done, but it’s too long, so I’ll snip it to size, and then hot glue it to the bottom side of the paper plate. While that’s drying, I’ll cut some holes in the sides of the bowl, to make it look more like a proper speaker basket. I’ll hot glue my magnet stack to the bottom, and slide the coil over top to see how it fits. It moves freely because of the gap I made earlier, and it’s looking good, so I can hot glue the plate to the bowl and hit it with a little spray paint for aesthetics. When the paint dries, there’s only 1 thing left to do, and that’s remove the coating from the ends of the wires, so I’ll do that with a lighter. Ok, It’s ready for a test, so I’ll hook it up to my TV with some alligator clips, and see what happens. Well there you go, my 80 cent speaker is working, and if “..a paper plate speaker for less than a dollar really is … too good to be true.”, then I’m calling this myth UN-BUSTED. But it’s not very loud. The magnets are cheap and weak, so I’m going to try something stronger. I’ll use this super strong 1″ N48 Neodymium magnet I just got in the mail. I’ll roll it up and add some 26 gauge wire I pulled out of a sump pump motor, and hot glue to secure it. The magnet and inner layers come out, and the paper gets trimmed to size. Hot glue that to the plate, and glue the lead wires right about here. This time I’ll use another plate as my base, and these markings are for some supports I’ll need to build. I’ll make those out of a 3rd plate, just by trimming out the bottom into a rectangle, folding them accordion style, and cutting into 2 pieces. I’m gluing them to my base plate with the feet facing inward, and these will act as a type of shock absorber for the speaker plate. I’ll add some glue to the tops, and join them to the plate making sure my coil is overtop the magnet. A quick manual test, and it seems the suspension on this is perfect. I’ll burn the coating off the tips of the wires, and now it’s time to test this one out. I’m disconnecting the external speakers from my TV, and using these alligator clips to connect the leads to my plate. I’m anxious to see how the paper plate does with the stronger magnet. That’s pretty impressive. It’s amazing to think that all that sound is coming from this flimsy little plate, but it is. Just for fun, I’m going to pour in some water to see what happens. That’s probably the coolest thing I’ve seen all day. Well that was a fun project. I UN-BUSTED a myth, and made a huge mess in the living room.
MythBusters busted it here.