Build a Bluetooth Boombox Speaker (from Scratch)

This tutorial will teach you everything you need to know on building a kickass DIY Bluetooth Boombox from scratch! This comprehensive video and guide was written so that even newbie makers can follow. No doubt that this speaker setup is really loud, portable and rechargeable as well.

If only I was able to make a live demo, this would be one of the loudest and clearest bluetooth boombox in the market. We're planning to sell a limited amount of these kits soon as well (assembled or unassembled).

I apologize, it's been a while since I last posted a tutorial here at instructables. I've been very busy with my studies lately. I'm currently taking a degree in BS-Electronics and COmmunications engineering (shifted out form BS Physics). Hopefully, one day, it would help me in building bigger and better projects.

MUST WATCH: Here's a in depth video tutorial on how to make one! This is the farthest I've gone in terms of incorporating high video production value with my tutorials. Enjoy!

Step 1: 100k YouTube Subscriber Anniversary Special

I made this long detailed video to thank you guys for helping my YouTube channel (TechBuilder) reach the +100,000 subscriber mark! As of now we have around 230,000 subscribers and counting. Thanks to YouTube's monetary support and Instructable's contests, I'm able to get funds for building better videos and projects each time.

Feel Free To SUBSCRIBE & Watch More DIY Video Tutorials!

Link:TechBuilder (Weekend Porjects!)

Step 2: Choosing Your Parts

Here's a step that I recycled from my previous instructable (DIY HiFi Bookshelf Speakers).

Plan, Canvas And Gather Information:

Before you go crazy on shopping spree. Be sure to read more articles in the net, canvas more about their prices, read more reviews and take a lot of consideration in selecting brands. I'm a practical kid, I try to buy things worth my budget.

Speaker Drivers:

To start off, Parts Express (online site) is a great source for speaker sales. Brands that I recommend buying are Dayton, Focal, Fostex, Seas, Tang-Band & Zalytron.Try to find speakers that can reach a wide range of frequency. For woofers, a frequency response of 60Hz - 6kHz are good to start with. A frequency response of 200Hz - 6kHz for midrange speakers and 4kHz - 20kHz for tweeters.Remember that the human ear can only hear 20Hz - 20kHz of audio frequencies so don't get excited if you find speakers that can go above or below the audible frequencies, it would be a great impracticality.

The Crossover:

Audio crossovers are a class of electronic filter used in audio applications. Most individual loudspeaker drivers are incapable of covering the entire audio spectrum from low frequencies to high frequencies with acceptable relative volume and absence of distortion so most hi-fi speaker systems use a combination of multiple loudspeakers drivers, each catering to a different frequency band. Crossovers split the audio signal into separate frequency bands that can be separately routed to loudspeakers optimized for those bands.As much as possible go for the bessel or linkwitz type of passive crossovers. They are the most common type of crossover filters, it has been and will always be the trusted and safest.

Enclosures:

There are two commonly used speaker enclosures, one is the ported and one is the sealed. The sealed enclosure is perfect for small speaker enclosures, it dampens the sound given off, resulting to a punchy sound rather than the woofy effect. The cons: is that this design will require a 100% airtight enclosure for it to be effective. The ported enclosure is only ideal for large speakers (+ 6.5 inch").

My Speakers/ Drivers:

http://www.audioholics.com/diy-audio/building-a-do...

Step 3: Tools & Materials

Here's a list and link of all the things I used to make this project. Some of the links below are just alternatives since I bought most of the materials locally. I still recommend sourcing your local shops ans suppliers for cheaper and better parts.

Electronic Components:

- 2x25W Bluetooth Amplifier Board (w/ Commands)

- 18560 Rechargeable Li-Ion Batteries (4x)

- Dome Tweeter Speaker Drivers (2x)

- Passive Audio Crossovers (2x)

- Woofer Speaker Drivers (2x)

- AC Plug (w/ Switch)

- 12v Powerbrick 2A

- Slider Switch

- DC Jack

- Wires

Optional Materials:

- Lithium Battery Pack Balancer

- Lithium Battery Charger

- Lithium Battery Holder

- Battery Voltage Monitor

MISC:

- MDF Wood Material (from local lumberyard)

- Masking Tape & Ductape

Tools & Equipment:

- Husky Tool Set

- Wood Clamps

- Hacksaw

- Jigsaw

Step 4: Sponsor

Finally got to work with BANGGOOD.com! I've been buying a lot of from them ever since. They offer a lot of cheap quality electronic kits and components! They also offer fast free shipping and have a great customer service! Now, they're now one of my official sponsor. Yay!

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If you are instrested in sponsoring me with my projects, instagram, YouTube channel and Instructables; feel free to contact me in my contacts below. We can make arrangements for endorsements and sponsorships. I barely charge anything, as long as you provide me with the components.

Contacts:

Email:casithebuilder@gmail.com

Facebook:Angelo Casimiro

Instagram:@AngeloCasi

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I highly recommend their website to you guys, my fellow makers!

Link:Banggood.com

Step 5: DIY Battery Pack

Most modern day appliances use Lithium batteries inside them mostly because Lithium batteries have a high energy storage to size ratio. This means, you get to store a lot of charge in small packages of rechargeable batteries.

For this project I used 18650 Lithium-Ion batteries. They're cheap, common and safer than Lithium-Polymer batteries. 18650 batteries are also called vape batteries. If you opt not to order online, just go to your local vape shop and you will be able to find a lot of these.

The bluetooth amplifier board that I used in this project requires an input voltage of 8v-25v, this means we need to put together at least three of these batteries in series which will give you 11.1v of power. We have to anticipate the voltage drop everytime the boombox discharges so to be safe, I used a 4 cells of lithium batteries (four 18650s in series).

This is a basic unprotected setup. It requires a monthly balancing in charging. If you have an advanced know how in electronics, I suggest adding a Li-ion balancing circuit protection board to prevent the cells from having uneven charges. This will reduce the risk of Lithium battery fire and explosion incidents.

Step 6: Measure the Components

Your parts may vary form mine, depending on your selection of materials. You'll have to use a ruler and a vernier caliper to acquire the measurements of the parts that you have. After you do this, write them down on a piece of paper, you'll be needing them in the enclosure designing step.

Step 7: Building the Ideal Enclosure

Building good speakers require a little tad of engineering. You don't just put speakers on a box. If you want to get the most out of your speaker's specs, you'll have to design a special speaker enclosure in accordance to your speaker driver's datasheets.

Using mathematical formulas are inevitable, but most of us are unfamiliar with them right? Yes! Here's a link of an online calculator app that will automatically solve for your enclosure dimension needs. It also comes with instructions and explanations on how to use it.

Link:Online Speaker Enclosure Calculator

Full Tutorial On Making Enclosures:

- Speaker Box Design (DIYaudio.com)

- Building and Designing Enclosures

The Calculators I Use:

- DIY Speaker Enclosure Calculator

- Speaker Enclosure Output Calculator

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Here's a video on the concepts of the common enclosure setups:

Here's a video on how to build your own speaker enclosure:

Step 8: Layout the Cutouts

After finishing your enclosure's blueprints, start to lay them out on your material. I chose the infamous MDF material (1/8" thick) simply because it's light and rigid. You'll need to use your straight ruler, L-ruler and compas for this step.

Why use MDF? (source: diyaudioandvideo.com)

The speaker box should be constructed from Medium Density Fiberboard (MDF). See the MDF Board FAQ for more information on obtaining and using MDF, along with safety issues. You should use minimum 3/4" MDF which is sold in 4x8 sheets. You will probably need 2 sheets. This can cost up to $20 a sheet, but it is worth it. MDF is a somewhat like particleboard in that it is made up of wood fibers glued together. The difference is the density of the fibers in the wood. Fiberboard is denser, harder, and stiffer over plywood and particleboard. It is a dead wood that won't resonate. It does not have the problems of screws being easily pulled out or easily warping when exposed to water like particleboard. Compare the top sheet, which is MDF, to the bottom sheet of particleboard. You can see that the MDF is much more dense.

Step 9: Cut Some Wood!

If you don't have access to high-tech woodworking shops, all you need is your good old jigsaw cutter and hacksaw. Just simply cut wood by following the layouts that you drew earlier.

Here's a tutorial by HowCast on using a jigsaw:

Step 10: Cutting Round Holes With a Jigsaw

In my early years of building speakers, cutting holes are one of the most difficult jobs for a newbie. I don't have a router cutter, but I do have a jigsaw and it will most definitely do the job! Using your power drill, just drill a huge hole in the middle to give way for the jigsaw's blade.

Step 11: Technique Tips! (Cutting Like a Monkey)

If there's one thing Asians are good at, it's doing things differently. I barely use clamps, woodworking benches or assistive tools. I just use all my body parts such as my feet, hands, elbows and forehead to grip, hold and push just about anything. Safety wise, it's not that great. Workmanship wise, it's Asian level, hahahaha! :)

Step 12: Drill Holes for Mounting

Now, temporarily mount your speakers in place. Align them, then mark the mounting screw holes with a pencil then drill them using your power drill.

Step 13: Saw the Back Panel

For the plugs and all the other peripherals, you'll have to cut holes for them as well. You can do this by transferring the measurements once more then use your jigsaw to make the holes.

Step 14: Sand the Panels

The wooden cutouts may be rough on the edges, so use a coarse grit sandpaper to smoothen them out.

Step 15: Temporary Glue

My MDF material is 1/8" thin, this means screwing them in place would pose as a problem. Like most people do, I don't have a lot of clamps for woodworking so using woodglue isn't much of a choice, since it takes a lot of time to set and dry. The answer this problem is superglue! It sets and dries in just minutes although it doesn't hold that well compared to superglue. We'll be using this as a temporary hold for the enclosure. Don't worry we'll use woodglue to enforce it later on.

Step 16: Cut Some Braces

Adding some braces to your enclosure would make it stronger and much more rigid. The more rigid your enclosure is, the less vibrations it will give out. The less vibrations you have, the better the audio quality is (less audio distortions). The wood I use was a (1/3")x(1/3") block. You can most probably find on in your local lumberyard.

Step 17: Brace the Enclosure

Step 18: Clamp and Seal the Edges

Once you're done bracing the enclosure, it's time to seal the edges with woodglue! Woodglue will bond with the MDF as if your enclosure came fro one big block of wood, it's very strong! Using woodglue will also seal off the gaps, preventing unwanted air to escape from your enclosure.

Step 19: Hairdryer! for a Faster Dry!

Tip: If you want to accelerate the drying process, use a hairdryer! It will definitively cure the wood glue in just minutes! I still do advice to let the glue dry under the sun for hours.

Step 20: File the Edges

The wooden panels may have uneven edges. To give it a professional look, gently file them until it levels out to the plane or panel.

Step 21: Choose Your Cloth

I chose to gave my boombox with a fresh and modern denim and canvas finish! I headed to my local tailor's store and bought some cloth for my project.

Step 22: Cut & Prepare Your Cloth

I had no prior experience in tailoring but I guess it worked out really well after a few hours of working with cloths. I I emptied my table, laid the cloth then marked it using a ballpen. For cutting the cloth, use some sharp shears as well!

Step 23: Start by Gluing Denim to the Side Panels

For gluing the cloth to my enclosure's wooden surface, I used a bottle of contact cement. Elmer's glue would just soak and ruin your cloth but contact cement wouldn't. Contact cement is waterproof and bonds well with the wood and cloth. I started by pouring contact cement on the side panels, then I spread it using a paint roller. I wrapped the denim around my enclosure and waited it to set once more after a few hours.

Step 24: Meeting the Ends

Making the ends meet beautifully gave me a little challenge. Carefully use your scissors to cute the denim until both ends meet. There will be a few strands cloth dangling around, use a lighter to burn them out (as if you were cauterizing a wound).

Step 25: Gluing Cloths in the Ridges

Contact cement wouldn't work in gluing cloth to the ridges, so I quickly applied superglue to the surface of the ridges and carefully pushed the cloth against it. After doing so, I cut the excess cloth out using my sharp set of X-ACTO knife.

Step 26: Apply Contact Cement Again

I opted not to cover my whole boombox with denim. I gave it a different taste by gluing red canvas on the front and rear panel which complemented with the denim's color really well.

Step 27: Glue the Remaining Cloths

Step 28: Cut the Cloth to Give Way for the Speakers

To give way for the speakers and all the other components, use a X-ACTO knife or a regular cutter blade to remove excess pieces of cloth. Use a soldering iron to burn out the edges if you must.

Step 29: Let the Contact Cement Dry Under the Sun

I left my boombox enclosure to dry under the sun to ensure that the cloth would bond with the wooden surface of the enclosure.

Step 30: Install the Handle

A classic boombox would be nothing without a kickass handle! So I went to my local hardware and found a cheap and beautiful aluminum handle from the cabinet section. I drilled a hole on top of my boombox, then screwed them right in place.

Step 31: Hotglue the DIY Battery Pack

I simply hot glued my DIY Lithium battery pack on the lower section of my enclosure.

Step 32: Wiring Diagram

Let's move on to the electronics. I've prepared this simple block diagram for all the components and how to wire them up. It's pretty simple!

Step 33: Solder Wires to the Speakers & Crossovers

Before you mount the speaker drivers, solder some wires so you wouldn't have to solder later on in tight spaces. You may choose mount the crossovers by hot gluing it or you may also screw them in place.

Why Use A Crossover?

Step 34: Screw the Speakers

Using some screws, washers and some nuts & bolts, you can now mount the speakers in place.

Step 35: Modify & Install the Power Brick

I wanted the boombox to operate using power from the wall outlet so that I wouldn't have to drain the batteries most of the time, so I dismantled an AC adapter that I had lying around.

Note:

This is only for powering the speakers, not for charging lithium batteries directly. I use an external hobby charger to do it. If you want to use the brick as a charger, you would have to buy a Lithium balancing charger circuit that I had posted on the "Tools and Materials Step".

Step 36: Install the Bluetooth Amplifier Board

Install the amplifier board in place.

Step 37: Add Command Buttons (Part #1)

The bluetooth amplifier board also comes with command buttons! Although, even if mount it with screws, the buttons would be unreachable from the back panel. So solve this problem, I made some plastic pushers out of an empty ballpen's plastic ink cartridge. I superglued the pushers to the button. Becareful not to put too much, otherwise you're buttons will get stuck.