Introduction: Graffiti Boombox Bluetooth Speaker
This is my second instructable, I hope this will help you with your builds. I wanted to build a loud portable speaker with good sound and design. This may be my biggest project yet. I am not a professional woodworker, but I am happy with the result and I am glad I can share the build process with you.
Step 1: Schematic and Things Needed for the Build
1. Speaker box
2. Amplifier tpa3116d2 2x50w+1x100w (subwoofer)
3. Bass speaker - Dibeisi DBS B1010/8 OHM
4. Midrange speakers - Dibeisi G4002/8 OHM
6. Frequency filters (the tpa3116d2 amp has a woofer filter built in on the 100w channel)
7. Bluetooth module.
8. Common ground filter
9. DC-DC Boster (the amp uses 24 volts) - i used 250w booster
10. 12v LED battery meter
11. Small 12v fan
12. 12v Music controlled led strip (optional)
13. 4x on-off-on-6-pin-dpdt-3-position-snap-in-rocker-switches-ac-6a-250v-10a-125v-1
14. 10amp Fuse
15. 3s BMS (20A version)
16. 1xT connector
17. 2x4 wire JST connector
18. 12v li-ion pack
19. DC plug 5,5mm
20. 2x Bass reflex cone 10cm long 5cm diameter
Step 2: Build Speaker Box
For the speaker box i used 18mm thick plywood. The interior of the box for the 25cm bass speaker should be at least 50x40x20cm. I used 2 pieces of plywood 53x41cm for the front and back, 2 pieces 41x20cm for the side and 2 pieces 20x50cm for top and bottom. I used pocket hole jig and polyurethane wood glue to make the box. When the glue was dry i used wood filler to fix imperfections and sanded with 220 grit sandpaper. Cut the holes for speakers,buttons, etc. with the jig saw. After that i painted the box white with matt paint. This is the base for the graffiti coating. I printed the graffiti picture on a laser printer (important). I used transfer medium to tranfer the picture to the box. Use water to remove the paper and matt varnish to protect transfered picture. For the handle i used some profiles i had home. The music controled led fitted perfectly inside the handle.
Step 3: Prepare for Wiring
Before you start wiring instal speakers, speaker cabinet damping material,buttons and try to make a sound test. Make a schematic on paper and a simulation with the parts to see if they fit inside the box. Keep in mind that parts may get hot and leave space around them to cool. I used a 12v fan for the amp. I made a 12v 10600 mAh pack from 18650 cels i recovered from broken cordless drill.
Step 4: Wiring
First of all please be careful with polarity, double check every time and do this in steps, li-ion cells are dangerous, wrong polarity may result in fire or explosion. Charging can be made thru the BMS with external 12.6v (max) power source but it will be not balanced. The BMS stop charging when one of the cells reaches 4,2 volts. That means that one or more of the cells may not be fully charged. The BMS will not start until you apply first time 12v to output terminals. The other method, much better, is to charge with a balance li-ion charger, i use IMAX B6 (that is why i mounted the 3 position switches, so i can fully detach the cells from the circuit and use a balance charger). This way you can also use the pack to power other things if you need it. The speaker is portable, make sure nothing will move, even wires, use shrinking tube insulation to make sure nothing can make a short circuit. Use hot glue, double side tape or any other method. I also recommand you use different colours of wires, this way it is harder to mess up. When you finish wiring make a test and if it is ok you can start to add speaker cabinet damping material. I used some foam that i had home but it was not enough, i added some material from a pillow. At this stage you can experiment with more or less damping material.
Step 5: Finish
This is the result, the sound is ok, great bass. I added one more switch to stop the subwoofer until i turn on the amp to avoid the pop sound. I hope i could help you.
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