Introduction: DIY Portable Boombox (from SCRATCH!)
I made this guide as specific and as step by step as I can, the only thing that dragged me down from finishing my boombox early, was the documentation for instructables that I did for this project. I hope you enjoy it!
My version was so efficient that it even had the capability to beat or match-up the sound of the Monster™ Beatbox (by Dr. Dre), Zeppeline™ Air, Altec Lancing™ IMT800 and IM7. My boombox has the capability to release a clean, deep and low bass, with the perfect midrange level and has a spectacular treble that seems to sooth the ear. It has a two way speaker system which will definitely reduce the amount of distortion given off by the speakers thus improving your audio experience.
Frequency response: 45Hz-20kHz
Max Amplifier Wattage: 2x30W Stereo
Total Harmonic Distortion (THD): 0.1%THD
Max Speaker Wattage: 150W-200W RMS
Speaker Size: Woofer (5.25"), Fullrange (1.75")
Enclosure's Dimensions: H= 5.75", L= 19", D=6"
Other Feature's: iPod Dock, USB Media Reader, IR Remote, Bass Trebble Equalizer and etc.
Audio Input Type: RCA, Auxiliary (3.5 Stereo) and 30 pin iPod Dock.
This project is ideal for: Picnics, Parties, Car Road Trips, Home Use and etc.
If you don't have time reading the long texts, there are summaries written in bright red text below each step.
"It takes pure craftsmanship and experience to build a highly efficient boombox from scraps and pieces. "
Step 1: Tools and Materials
Click on the item to see where to buy it.
- Electric Drill
- Electric Jigsaw
- Electric Sander
- Glue Gun
- Soldering Iron
- Desoldering Pump
- Woofer Speakers (2pcs.)
- Fullrange Speakers (2pcs.)
- High Quality Amplifier (with 2 knob equalizer)
- RCA Jack
- Auxiliary 3.5 Stereo Jack
- 4700uF 25V Electrolytic Capacitor (2pcs.)
- 47uF 25V Electrolytic Capacitor (2pcs.)
- 1K 1/4 Resistor
- LED Light Blue
- Power Switch
- iPod dock to auxiliary cable
- Metal Potentiometer Knobs
- USB/SD Card Reader Module
- Round Plastic Containers (2pcs.)
- Black Quick Drying Enamel Paint
- Paint Thinner
- Paint Roller With Tray
Step 2: Choosing the Best Speaker, Amplifier and Enclosure for Your Project
Of course, three of the main components of your boombox are your amplifier, speaker and your enclosure . The three of them are considered to be the major factors that can affect the speaker's performance. In this step, I am going to give off tips on choosing the best speaker, amplifier and enclosure type for your project and the other options that you could use for your alternative. If you are knowledgeable about amplifiers and speakers you can skip this step.
Plan, Canvas And Gather Information:
Be sure to plan everything before you buy your wood, speaker, amplifier and everything. Also consider the space that is limited on where you are going place your boombox. Try to research first before you buy everything. After researching, write it doen on your blueprints
Before you buy a pair of speakers, try to research on different brands that are reliable and have been known for producing speakers with excellent quality, brands like Dayton, Tangband, Focal, Seas, Fostex and Crown (only found in the Philippines). I chose the brand of Crown since it was known for cheap speakers with excellent sound quality, I also had great experiences with it. Try to buy speakers that can exceed 80W of audio power. Do not be fooled by the maximum wattage of the speakers, it all depends on the audio quality.
Also try to find speakers that can reach a wide range of frequency response. For woofers, a frequency response of 60Hz - 6kHz are good to start with and a frequency response of 200Hz - 20kHz for fullrange speakers are recommended. The wider the better! Mine has a two way crossover design so both speakers combined should reach 45Hz - 20kHz (without a frequency gap)
Remember that the human ear can only hear 20Hz - 20kHz of audio frequencies so don't get excited if you find speakers can go above or below the audible frequencies, it would be a great impracticality.
You can easily judge a speaker by its appearance, the magnet size, the cone's material, the size of the rubber surround, the wieght, the size and the beauty of its design.
The first time I found my speakers in the store, I easily goty excited to buy one, when I found the over sized magnets and the wide rubber surround design with a thick polypropylene cone, I told myself that I should buy these someday. When I checked the specs and its price, I was extremely impressed, everything exceeded my expectations.
Its better to make your own amplifier, I built an amplifier with a TDA8569 (2x40W BTL) amplifier chip and connected to a TDA1524 tone control circuit (Bass, Treble, Volume and Balance Knob). Chip amplifiers are definitely more energy efficient than MOSFET amplifiers. You can choose to make one or to buy one, if you are experienced in making amplifiers I suggest to make one, the TDA1554 (2x22W), TDA7394 (2x30) and TDA8560 (2x40W) sounds terrific and also try the TDA1524 tone control chip. If you don't know how to make circuits you can try to find a ready made car amplifier. Making one is cheaper than buying a ready made.
If your amplifier and speakers are good but your enclosure is poorly designed, the sound quality will greatly be affected. There are two commonly used speaker enclosures, one is the ported and one is the sealed. Try the method of bracing, bracing is the of additional support structure added inside the speaker enclosure's edges, in this way vibrations can be eliminated outside the enclosure thus giving a better audio experience.
The sealed enclosure is perfect for small enclosures, it self-dampens the sound given off. The pros is that this enclosure can be used for small and compact enclosures, and gives of a smooth and damp sound while 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") with large enclosures.
You can use a ported enclosure and just plug a thick foam into the port for it to be a closed enclosure although air could still escape.
Summary: Just buy a good speaker, amplifier and research on the different types of enclosures that best suit your use.
Step 3: Measuring Every Part Needed
After choosing and buying the desired components for your boombox. It's now time to measure everything for your blueprints. Use a caliper, ruler and measuring tape to measure everything then write your measurements on a piece of paper.
Summary: Measure everything then write down your measurements on a small piece of paper.
Step 4: Marking the Lines for Cutting
In this step a little bit of Math, numerical calculations and measuring will be needed. Try to put your blueprints and a piece of scratch paper by your side. You might also need a calculator. Try to recycle wood from your other projects. Every piece of wood that I used for this project was recycled from my previous tower speaker project.
Write the main markings with a ballpen and the guidelines with a pencil.
Summary: Get your blueprints and write down the exact measurements on your wood, this will be your guide for cutting the wood.
Step 5: Cutting the Wood (Jigsaw)
It's time to cut your wood using a jigsaw. A traditional handsaw can do but using it would be tiresome and can give off unclean cuts. If you are using a jigsaw, try to buy a curving blade for a better and cleaner cut for the round holes for the speakers. A traditional way to cut holes for speakers is to use a jigsaw but first you need to drill a hole inside the speakers marking to have a start for the jigsaw cut.
Summary: Get your jigsaw and drill to cut down the wood.
Step 6: Sanding the Previously Cut Wood
I used an electric sander for a cleaner finish but you can also use a regular sanding paper. There will be two sanding sessions, one before gluing step and the other will be done after the wood putty application step.
Summary: Sand your wood using an electric sander/ sanding paper for the wood glue later on to stick properly.
Step 7: Gluing and Assembling the Enclosure
Glue the whole enclosure together according to your design. Try the method of bracing, bracing is the of additional support structure added inside the enclosure's edges, in this way vibrations can be eliminated outside the enclosure thus giving a better audio experience. Do not forget to leave the back part unglued, the back part will used later on for the wiring of the components.
Summary: Glue everything in place, use bracing if needed.
Step 8: Time to Drill and Cut Holes (Last Time for Cutting)
Now is the best and final time for cutting and drilling holes for your knobs, switches, iPod dock, connectors, USB/SD audio player module. Later on you will fill the gaps using your wood filler (putty), then sand the box for the last time, then paint or laminate your box for the final finishing.
Summary: This is the last time for drilling and cutting holes for your accessories.
Step 9: Applying Wood FIller
Apply wood filler before you start your second sanding session, by applying the wood filler, the edges would appear to be connected with each other, it prevents gaps that can ruin your enclosure's design and appearance. Later on you will sand the enclosure for the second time with the wood filler all dried up, doing this could result to having smooth edges and flat surfaces.
REMINDER: It is fine to has an excess layer of wood filler because later on you will even out the enclosure's surface by using your electric sander.
Summary: Fill the gaps and cracks using your wood filler (putty).
Step 10: Sanding the Assembled Enclosure
Use your electric sander to even out the excess wood filler on the surface of your enclosure. You can use a regular piece of sanding paper although this method is very tiresome and less efficient compared to the electric sanding method.
Summary: Sand the enclosure for the paint to stick properly (cosmetic purposes).
Step 11: Clean It for the Last Time
Be sure to give your best on cleaning the enclosure, if you don't clean it properly, the paint that you will apply, might not stick on the wood's surface. If not done properly, your paint will eventually flake-off in the near future.
Sorry, in this picture, I haven't apply the wood filler yet, just don't mind it and just follow the steps.
Summary: Clean the wood for the paint to stick properly.
Step 12: Painting the Enclosure
Wake up early in the morning to paint the enclosure for you to have a longer time to expose and let your enclosure dry under the sunlight.
Use your paint, roller, tray and thinner for painting your enclosure. Add thinner to your paint if your paint is to thick and to sticky. You can also use a can of spray paint instead of the roller method. For others who know how to laminate wood, try it. I chose the roller method since enamel paints are thick, durable and would last for a long time.
Read your paint's can and see what is the required time for the paint to dry and settle. Mine was a quick drying enamel based paint so it only took me 4 hours to dry the enclosure, I left it under the sunlight for 12 hours to ensure it dries properly. It's better to coat 2-3 layers of paint for the cracks and gaps to be covered.
I took some of the photos during night time that's why it is so blurred and dark.
My paint got ruined by the rain so I used a self adhesive roll of vinyl wallpaper.
Summary: Paint the whole enclosure using your roller, thinner and paint. Paint your enclosure 2-3 times.
Step 13: Sealing Your Fullrange Speaker Into a Cylindrical Container
Sealing your fullrange speaker into a smaller container would reduce the amount of distortion. Now its time to solder the 47uF (25V) capacitor to your speakers as a simple crossover (frequency limiter). Solder the black wire to the negative terminal of your speaker, then solder the positive terminal of your speaker to the negative side of your capacitor, after that solder the red wire to the positive side of the capacitor. Just follow the simple schematic diagram below.
I have a second version of my boombox. There were lots of improvements and revisions, including the crossovers and speakers. The crossover is now a "2nd Order Butterworth". Every part of the 2nd version is top secret, its my secret recipe. This version in this instructable is just a prototype, so please do not complain why did I just add a very small capacitor for my crossover.
Summary: Add a separate enclosure for your fullrange speaker, this would reduce distortion. Also add a capacitor as a simple crossover.
Step 14: Making the IPod Dock
Disassemble your iPod dock audio cable then remove the locking pins. Find a thick and soft aluminum sheet then bend it, after bending the sheet, use your glue gun to fasten the iPod cable to your bent aluminum sheet.
Summary: Hot glue your iPod docking cable on a bent aluminum sheet.
Step 15: Assembling the Boombox
Now that you have your enclosure ready. It's time to plug your glue gun and soldering iron. Its time to screw-up, glue-up and wire-up the speaker, amplifier, knobs, switches and plugs.
If you find small holes, gaps and cracks from your switches, speakers, plugs and everything, try to seal it with some hot glue, sealing it would prevent the air from escaping the enclosure. Remember it has to be 100% airtight as possible.
Try to become creative in wiring the LEDs in different places, this will reflect on your artistic and creativity skills.
There is a simplified schematic below (2nd Picture)
Summary: Assemble everything, use your glue gun to seal the remaining gaps.
Step 16: Leave the Rear Part of the Boombox Screwable
Leave the rear part of the boombox screwable, this would be useful for modifying the boombox in the near future. Use a strip of rubber gasket or a thick strip of padding tape to seal the rear part of the speaker then add screws around the rear panel proportionally.
Summary: Leave the rear panel screwable for further modifications.
Step 17: Your'e Done!!!!!
Enjoy it! Please rate this guide if you liked it!
The audio quality all depends on your planning, material selection, creative designing, enclosure type, power source and everything you choose.
Step 18: Additional Modification Ideas
- Adding a built in battery pack (18V Lithium Ion)
- Adding a Bluetooth/ Airplay module (Wireless Audio)
- Adding an external subwoofer output
- Adding a LCD panel
- Laminating the wood
- Upgrading the TDA7394 (2x30W) amp with a TDA8560 (2x40W) amp
- Replacing the transistor tone control with a TDA1524 chip tone control
- 3 Way Speaker System
- 3 Way Linkwitz Crossover