Drums can't bang without skins, and our Bluetooth boombox project can't sing without speaker drivers.
We've got our vintage suitcase and our ONEU 50 watt Bluetooth amplifier from Amazon, so now we need to fill this thing with drivers.
The type of speaker driver we're going to use is new and special. It's called a "balanced mode radiator," and it's been used mostly in TV sound bars since its invention.
The reason it's good in sound bars is the same reason it's going to be good for a Bluetooth speaker: It's designed to radiate all sound uniformly, meaning it sounds the same from any angle.
We're talking about what's called the speaker "dispersion pattern." With most speakers, we get sound in all directions only at the lowest frequencies. As the frequency rises — as the sound becomes higher in pitch — the sound becomes directional. Up where the sound of cymbals and chalkboard scratches reside, it beams like a laser.
Not so with these balanced-mode radiator speakers from Tectonic Elements. Their dispersion pattern is roughly uniform throughout the whole audio spectrum, making them perfect for our project.
Another benefit of being a driver designed for commercial products like soundbars is that these suckers are cheap. So we're going to get a bunch of them. Connecting them in parallel with each other (and also in series if you use more than 4) will be the key to getting some volume out of this battery-powered Bluetooth boombox.
Visit parts-express.com and search for "BMR." We want the 3.5-inch one. While you're at it, search for some hookup wire — you'll want a few meters before we're done.
Here's where you can make this project your own. The basic project calls for two of these 3-inch BMR drivers per left/right channel, but you can really do as many as you can fit on one side of your suitcase. Whatever amount you choose, make sure it's an even number on each side.
Remember my advice to glue a ¼ -inch plywood board behind the side of the suitcase that we'll mount the drivers on? Well, unless you're using a hardshell case, it's probably going to be required in order to mount the drivers.
There is a cardboard circle cutout that comes with the speakers that will serve as a guide for marking the holes. Cut your holes carefully, and mark the screw mount holes with a sharpie. Your local hardware store can help out with mounting bolts and nuts.
I'm assuming that if you're going this far with an audio project like this, you can twist the wires to the speaker terminals — or solder them if you can. Another option is to use crimp connectors, which you can also find at Parts Express or your local hardware store. Make sure to get a crimping tool as well.
I was hoping to wrap this up in two columns, but we'll have to save the electrical connections and final tweaks for next week. By the end of this awesome project, you'll have a cool-looking Bluetooth boombox that runs on batteries and really bumps. Being able to say you made it yourself is the best part.