Simple Mini Bluetooth Boombox

Intro
Music fills the air without effort, like waves filling holes in beach sand; the sound rushing in and around every person in the room. Some react to the beat, others continue in chatter, but always it speaks to them in some manner. People spend countless amount of dollars in order to buy a speaker or boombox that will give them the sharpest, clearest sound imaginable. Yet, oftentimes these units can be quite costly, and many are daunted by the prospect at making your own sound system, much less a portable boombox. However, with a thorough amount of time and effort, making a boombox isn't so difficult. Today, I'll show you how.

Determining The Right Supplies
Figuring out what parts you want to use can almost be as daunting as hooking them up altogether. There are several key things to make note of when buying your parts.

1) Tweeter Or Woofer? What are they even?
How-To Geek has a great explanation of what a Tweeter and Woofer is and the difference between the two:

https://www.howtogeek.com/354985/what-are-woofers-...

To put simply, however, a tweeter is smaller, emits higher frequency sounds, and requires more voltage. A woofer, on the other hand, is bigger, emits lower frequency sounds, and requires less voltage. Normally, the best thing to do is get one of each so you have the best of both worlds. However, this leads to the problem of crossover distortion. Essentially, if there is overlap on the frequencies they play, they will play the overlapping frequencies at the same time, causing distortion. To solve this, one would need to create or buy an active or passive crossover to be the medium between the amplifier and the speakers.

For this project, I'll be using 2 midrange speakers as I want to keep the size of the boombox as small as possible.

2) Passive Or Active Crossover?
If you do plan on using both a tweeter and a woofer, it is highly recommended that you get a crossover. Active crossovers are smaller, easier to use, but they require voltage and may interfere with the speakers not getting enough power depending on the Hi-Fi you bought. Active crossovers, on the other hand, tend to be bulkier. Once more, for this project, I am not using a crossover as I am using two identical speakers as I want this to be as small as possible. I only put this information here in case you wanted to make adjustments to this project for your own use.

Also, a small side note. Some speakers come with a passive crossover, however, they are oftentimes more expensive.

A great article on the subject:

https://blog.sonicelectronix.com/passive-vs-active...


3)Voltage And Ohms
Loudspeakers often time require a lot of voltage in order to be used properly. Many tweeters, for example, require at least 100 volts of power, where many lower-cost Hi-Fi speakers emit much less.

With this, you must make sure that your ohms or electrical resistance between the two points are compatible, or else they will not work or possibly be damaged.

On the other hand, many speakers and amplifier systems come with a range of ohms and volts they are compatible with. However, some are a better match for others. Sadly, I did not learn about this until I was halfway through the project.

Here is a great article about it:

https://www.gcaudio.com/tips-tricks/the-interrelationship-of-speakers-and-amplifiers/

Supplies:

Minimum Supplies
Hi-Fi Kit with Amplifier And Bluetooth Speaker
The One I Used: https://www.amazon.com/gp/product/B07QKW2WMF/ref=p...

2 Loudspeaker's
The Ones I Used: https://www.amazon.com/gp/product/B00009QOU5/ref=p...
{Note: Looking back, there are many better speakers one can use for this project. I'd not reccomend this one. Keep in mind that you will have to keep the voltages in mind and make sure that the speakers themselves are between 4-16 ohms, or else you will have to find a different Hi-Fi kit.}

Sandpaper

16 Gauge Speaker Wire (Depends If The Speakers You Bought Comes With it)
The One I used: https://www.amazon.com/gp/product/B006LW0WDQ/ref=...

Wood Paneling (I used 3mm)

Optional Supplies
Active Or Passive Crossover ( If you are using two different speakers.)
Wood Glue
Spray-paint
Led Lights (See Step 4)

Tools
Screwdriver
Compass
Caliber
A band saw (Or any Kind Of Saw)
Laser Cutter, 3D Printer, or any way to machine parts.
Hot Glue Gun

Teacher Notes

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Step 1: Building the Speaker

For this project, I bought 2 mid-range tweeters that don't come pre-made. A fair amount of speakers used for boom boxes or car stereo come like such. Despite this, it isn't all that hard to put together.

I did not need the round adhesive, so I stowed that to the side for a future project. The next step was pulling the wire through the plastic casing, making sure the wires align accordingly. Also, please make sure to note which wires are positive and negative, as that will come in importance later down the road.

After that, you attach the magnetic casing to the plastic one, and it should snap into place if aligned properly. The next thing to do is to make sure to secure it by threading a screw and kept nut through the hole at the bottom of the casing and speaker as shown.

Here is where I bought this set of speakers:

Step 2: Taking Apart the Hi-Fi

After the speakers are complete, you want to start taking apart the Hi-Fi into its base components by using a screwdriver. Since hi-fis are mostly used in car stereo systems, the casing has a lot of spare room to prevent overheating. However, this won't be a problem with our design.

After stripping away all the excess casing, we can see how small the actual components are and begin to make our casing from that. However, please make sure to note any extra details left on the casing as they may be important to you later on.

Here is where I bought this Hi-Fi:

Step 3: Electronics Side Note

Before we move onto the casing, I would like to note several key interesting things about this specific hi-fi's components. The first key component is that to the right of the positive and negative ports for the speaker there is an outlet for a direct current of 12 volts. This can be used to power LED's and other components to make this design more extravagant.

With this, there is also a small alternating current outlet upon the yellow circuit you see here. However, I do not know the voltage of it and have not attempted to mess with it. Someone more experienced with electronics, however, could have a field day with this.

Step 4: Taking Measurements

It's highly recommended that you measure all the various components before starting the cutting process of the wood paneling. The first major thing is measuring the diameter of your speakers. For the panel that will be containing the speakers, give an extra quarter-inch of room above and below where the speaker would sit. With this done, measure how long and wide the base of the speaker will need to be to comfortably fit all the components. The next important measurements that many people miss is measuring the thickness of the plywood.

With the most 3 important measurements, we can begin writing down how long and wide each piece will be. The height of the boombox would be determined by the height of the hi-fi + the wood panel where the speakers will be placed. The top and bottom panel will be the length of the hi-fi by how wide you decide to make it in order to fit all the components comfortably. The two side panels will be how wide the boombox is by the height. Then, the last panel is simply the height of the boombox by the length of the hi-fi.

***Please Note***
Keep in mind how thick the wood paneling is when deciding how long and wide each wood panel will be. If you don't, you may have to do an excessive amount of sanding later down the road like I had to do. Hot glue may also cause problem with precise measurements.

These are the measurements I used for my boombox:
Height: 5 Inches
Width: 5 Inches
Length: 7 3/4 inches

Side Panels: 5 by 5 Inches
Top And Bottom Panels: 7 3/4 inches by 5 inches
Back Panel: 7 3/4 inches by 5 inches with a 3/5 by 1/5 for the hole for the charger port 1 1/2 inches from the bottom on the very left. 1/2 cm hole 1 1/4 inches from the bottom, one inch from the hole. {Note: You do not need the holes to be placed in the exact same spot. These are where I just put it.}
Front Panel: 3 inches by 7 3/4 inches sanded down to fit snugly.

Step 5: Cutting the Boards

Unlike shown above, you should start sketching out the panels you need to be cut out with a pencil, as you may make a mistake or two. You also would like to have each panel measurement stacked upon each other to be able to use the least of the wood paneling as possible. This will also make cutting it considerably easier if you are using a band or handsaw.

If you are using a laser cutter for all of it, you must first cut down the piece to a size that will fit firstly. After that, you can make sketches using any CAD program of your choice and proceed to cut the panels with it.

For this project, I used a mixture of both in order to achieve the results I wanted. For the top, bottom and side panels, I cut them out using a bandsaw. Following this, I drafted two drawings to cut the back and front board as they required specialized cuts to fit the speakers and outlet cord.

See attached pdf documents for the front and back panel if you plan to use a laser cutter or 3d printer.

If you don't have a laser cutter:

Don't worry for a single second. If you have a jigsaw, that will be more than enough to be able to cut holes into the wood. Any hole saw smaller than the hole itself will also do, as long as you take the time of going around the edge of the circle and sanding it down. The most diligent can even suffice with a drill and drilling through the perimeter of the circle and sanding it down.

Step 6: Putting Together the Frame and Fixing Errors.

The next step, although the most simple, can be the most tedious and frustrating of them all. This is also where the sandpaper will come in handy as well, in order to fix minute mistakes measurements or not properly understanding how all the parts will fit together. I used roughly 3 sheets of sandpaper, although you can most certainly get away with less. The rougher the sandpaper, the better for this portion, as it is easier to sand it down to proper size.

I used hot glue carefully, trying to glue from the inside of the box when possible. This is tricky to do without accidentally melting the wires, so be careful. Alternatively, if you have wood glue and are willing to be patient, that will work better, as you can sand that down much easier in the next step and creates a stronger bond.

Step 7: Putting It All Together and Sanding It Down

Once you are done gluing together all the panels except the top and back panel, thread the speakers through the 2 holes, plugging in the speaker wire into the corresponding positive and negative terminals. The best way to glue these is by glueing the lip of the speaker and pushing it onto the wood. Once done, you are free to put on the top and back panel.

When putting on the back panel, make sure to pull the radio wire and cable through, gluing the thick portion of the cable to the hole we made earlier.

Once done, you begin to sand down all the sides with sandpaper to make them smooth and not clunky. Any sandpaper will do, just make sure it's not very fine. This process is very tedious and you will get sawdust everywhere, so just be mindful of this.

And that's all folks. Plug it in, attach it to your Bluetooth, and show it off to all your friends.

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