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This instructable is on building a 2.0 portable bluetooth Boombox.

For this build I sourced parts locally as well as from China.

In this build I've given two bass port at the bottom. The speaker is powered by a 12V 7Ah Sealed Lead Acid Battery and is having Bluetooth V2.0 + EDR connectivity. This might run for somewhere around 15-20 days on moderate volume. It weighs somewhere around 6 kgs.

I was aiming for a vintage radio look.

Hope the instructable will be informative enough.

Step 1: Material and Tools

List of Electronics:
- Amplifier Board (Aliexpress, 2*15W TDA7297 Dual Channel)

- DC-DC Step Down Converter (Aliexpress, LM2596 Step Down Converter)

- Full Range 4" Speaker Drivers 10W 8Ohm (Local Seller)

- Bluetooth Stereo Adapter Audio Receiver with AUX Cable

- Digital LED Voltmeter Panel

- 12V 2A AC Adapter

- 12V 7Ah Sealed Lead Acid Battery

- 12V Battery Charger

- 3 On/Off Switch (Single Pole Double Throw Switch)

- 3.5mm Female Jack

- Plug Male & Female

- AC Adapter Female Jack

Tools and Materials:

- 8mm MDF Board

- 2.5mm MDF Board (For Grill, Control Plate and Back Panel)

- Brown Rexine

- Soldering Iron & Solder

- Wire Snipper

- Screwdriver Set

- Wire

- Superglue

- Rubber Glue

- Glue Gun & Glue Sticks

- Wood Polish

- Leather Polish

- Wire Shrink Wrap

- Aluminium Volume Knob (Turned in College)

- Screws

- Acrylic Paint

- Washers

- Laser Cutter

The Final Dimensions of the speaker is 35cm x 18.5cm x 18.5cm.

Step 2: Cutting the Panels and Turning the Volume Knob

The enclosure panels are cut out of 8mm thick MDF board.

Dimensions for each panel is given in the images above. All dimension are in centimeter (cm). All the steps and slots are 4mm wide and 4mm deep. Top, bottom, left and right panels have double rabbet joinery.

http://www.table-saw-guide.com/rabbet-joint.html

I used a table saw to cut the outer dimensions of the panels. Then used a wood router to cut 4mm wide and 4mm deep rabbet.

I cut 3 pieces to enclose my battery. Cut pieces according to the size of battery you are using.

I drilled holes in the bottom panel for bass port. According to the frequency you are try to achieve make desired holes. You'll have to try and test the length of bass port. There are software available online using which you can calculate the length of bass port.

Volume knobwas turned out of aluminum. The diameter of the knob is 3.5cm and the height is 2 cms. A hole was drilled on the bottom to fit the knob of potentiometer.

I've also put an image which will give you rough idea about the way the panels will join.

I've attached the back panel and grill lasercut CAD files. I used 2.5mm MDF for lasercutting. You can change the slots made in the back panels according the the shape and size of ports you are using.

- Black Lines: Through Cut

  • Vector Cutting
  • Power: 100
  • Speed: 9
  • Frequency: 1250

- Red Lines: Half Cut

  • Vector Cutting
  • Power: 50
  • Speed: 75
  • Frequency: 1250

Red lines are used for branding and labeling the controls. So, we just need them to make a mark on MDF.

Step 3: Preparing the Different Components

The block diagram for the system is given.

Wiring the Amplifier

Positive from the On/Off switch is connected to the positive on the board. Negative from the AC jack, Battery, Bluetooth receiver is connected to the negative on the board. I soldered an extra led on the led points on the amplifier. I soldered the speaker wires on the board instead of inserting them in the slots, as the wires kept on coming out front it, but this was done once the speakers were put on the speaker mounting panel. I desoldered the existing 50K potentiometer and replaced it with a 20K one to increase the volume level. I plugged in a 3.5mm aux cable from the bluetooth receiver module into the 3.5mm audio in port on the board.

DC-DC step down converter

Step down converter was given power from the master On/Off switch. You'll need a multimeter to set 5V output by tuning the potentiometer on the converter. The output pins of the converter were soldered to the power terminals of the bluetooth receiver module.

Bluetooth Audio Receiver

Receiver is powered by the DC-DC step down converter and the audio signals from the device connected is fed into the amplifier using an aux cable connected to the receiver. You can solder a wire to the antenna of the module to increase the range. A 10 cm wire would be enough.

Voltmeter

I connected the voltmeter between the positive from the master switch and the negative of the battery. So, it will switch on only when battery is selected as the power source.

Power Source Toggle Switch

+ive from the battery and AC jack are connected to the side poles of the SPDT. The center pole of the toggle switch is connected to the master switch side pole. I've attached an image showing the wiring.

Master On/Off Switch

Output from the power source toggle is connected to the side pole. One wire from the center output pole is connected to the positive on the amplifier board, one is connected to the positive of the Voltmeter and one is connected to the Bluetooth On/Off switch side pole.

Bluetooth On/Off Switch

Output from the master switch is connected to the side pole. The center output pole is connected to the positive input on the DC DC step down converter.

AUX Input

Connect the aux to the back side of the 3.5mm port on the amplifier board. The pin closest to the face of the port is the ground terminal and the one's below are left and right channel terminal.

Battery Charger Plug

Connect the +ive and -ive terminal of the female charger plug on the +ive and -ive terminal of battery respectively. Attention: Make sure that you connect the polarity of the charger correctly or it may lead to accident.


Problems faced

After desoldering the 50K potentiometer and putting a 20K potentiometer I found out the only one of the channel was working and when the potentiometer was kept at zero position I could still hear music. The potentiometer head contact point had become loose and one of the control wire was disconnected. I had to put another one. So, before closing the enclosure make sure that both the channels are working and when the knob is at zero position no sound comes out of the speakers.

Step 4: Assembly

To assemble the speakers follow the steps

- Hot glue the speakers on the back side of the speaker mounting plate.

- Take the bottom panel and left panel, put wood glue on the rabbets and align them. Glue the bottom and left rabbets on the speaker mounting panel and insert it into the left and bottom panel slots.

- Put glue on the right panel rabbet and slot and insert it in the speaker mounting slot and alight it with bottom panel.

- Put glue on two sides of corners and place it between the panels.

- Use the blocks you have cut for your battery enclosure and glue them to the bottom panel.

- Put glue on the side rabbet and the slot on the top panel and align it with left, right and speaker mounting panel.

- Use nails on the corners to strengthen the fit of panels. You can drill holes also on the side of the panels and corners and then use screws to secure them.

- Once battery enclosure is dry place the battery in it and hot glue it so that it cannot move.

- Cut the rexine to fit the enclosure. Using rubber adhesive wrap the four panels with rexine. Keep some extra rexine on the sides to cover the edges. Be careful when wrapping the edges. I made 45 degree cuts on the edges so that it looks clean.

- Mount the switches, potentiometer, LED and 3.5mm female jack on the Control Plate in the order shown in the picture. Hot glue the components on the back side of the plate. Put a bit of hot glue in the turned aluminium knob and insert the potentimeter knob in it.

- Mount the control plate with the switches and potentiometer on the inner side of the top panel using screws. Use hot glue on the edges on the plate.

- Solder the speaker wire to the board.

- Place the voltmeter, battery charging female plug and AC jack on the back plate using screws or nuts provided with the ports. Solder the connections as instructed in the previous step.

- Hot glue the amplifier inside the enclosure according to the space available. You can also screw the board as well.

- Hot glue the bluetooth receiver module and DC-DC converter to one of the panel.

- Insert the bass port tube. I used a very thick millboard. And made it into a tube and glued it to the holes for bass port.

- Screw the back panel using 6 screws. Four corner screw were inserted into the corners. So make sure that the holes you make in the back panel is aligned to the hole drilled in the corner edge. For the center screw you might have to give 2 additional 8mm MDF tabs in which screws can be inserted. I used 6 screws cause the bass in the speakers was making the back panel rattle a bit. You can use a thicker 4mm MDF as well for the back panel.

- On the front of the speaker mounting panel put 4 pieces of 8mm thick MDF (3cmx3cm). Drill holes (smaller than the dia of screw) in these pieces according to the holes on the grill.

- Screw the grill in place.

Step 5: Finishing Touches

I made footpegs using 1.5 cm wide and 17 cm long 8mm MDF. Then I superglued them to the base and drilled two holes in each footpeg Counter sink the holes so that the screws are inside the footpegs. I inserted 2 cm long screws so that they penetrate inside the bottom panel.

I painted the front of speaker mounting panel and the 4 grill mounts using white acrylic paint.

Using emery paper sand the grill and the back panel. I had lasercut my brand name Sonic Architect and superglued it to the grill with the help of marking I had made during laser cutting. Be very careful while supergluing the brand.

Apply wood polish to make the grill and front panel smooth. Polish the rexine using leather polish.

Check once that every thing is working properly. If it is then screw the back panel and grill.

I thought that I'll give the boombox a leather strap as handle but for some reason I haven't gone ahead with that. If I do add it I'll update the instructable.

Switch on the boombox, connect your phone and you are good to rock the party.


Any questions, comments or criticisms always welcome!

<p>Hey all I put together an Amazon list with all the parts (missing a few), would love feedback and or suggestions on where I can find the missing parts! Awesome build btw!</p><p> http://a.co/g2hjX34</p>
<p>my question is, if its Bluetooth? how are you supposed to use it? only bluetooth compatible thing i ever ran into is my Dull Shock 3.</p>
<p>You can connect your phone, computer via bluetooth to play music. And there is a 3.5mm AUX cable jack also which you can use to connect to any device having a 3.5mm headphone jack.</p>
<p>if my phone has a RJ11 connector on it. it never came in mind to play music threw it. </p><p>if im out the house i use my PSP or my rugged dell inspiron 8600, but i smashed it agin so im down to just psp untill i replace motherboard, gpu and back light and keyboard. i have spare parts, just putting it off.</p><p>and i used to have a walkman cd player a few years ago, but believe it or not some one stole it. who the hell steals a cd player in 2011.</p>
<p>He's talking about connecting your smartphone/tablet (or another device with bluetooth).</p>
<p>My smart phone? i think not! i dont know how to use those things and i dont want to. back in 2012 i was visiting my mom and she wanted me to do something for here on one of those android phones and that was the worst UI ever ever ever. also the screen sucked, was like 120p in resolution and had 3 buttons that always showed up on the screen instead of them being physical buttons. i dont know why any one would put up with that unless they were payed to do it.</p><p> i do have a M1400 tablet but no bluetooth. like i said only thing i ever ran into with blue tooth is my DS3 witch i use on my workstation/gaming rig at home over USB</p><p>and why did you say smartphone/tablet like there 2 words for same thing? tablets run desktop OS's and are basically laptops with no keyboard and a wacom touch pen screen. smart phones are slow minimalistic devices driven by firmware and cant properly even access gmail. </p>
<p>I'm not trying to start anything here...but...you are in the year 2016 you know that? Tablets and smartphones run the same Operating System, Android, Windows or OS, many of these devices are more capable of doing anything and they are very very fast, tablets dont use a pen anymore, and you tried a smartphone back in 2012...when they sucked pretty bad, now the things are much different. You have to upgrade your devices..if you don't have the money...ok i don't blame you...but don't say that they suck.</p>
<p>You do know by now that RockeyDA has been pulling your chains and getting exposure he couldn't get on his own</p>
Yhee he is a troll, nothing new in the internet, just ignore ;)
<p>i do not remotely believe you could run windows on a phone. websights have mobile variations because cell phones are not cabible of loading them normaly. and i dont got to upgrade anything, my motherboard was made in 2009 and im in the top 1% of prossesing power on steam. 24 thread system running at 4.2 Ghz, and my gpu is a 680 from 2012 running at 1.4ghz, gets better frame rates than my fiends 780 with factory overclock. and my tablet witch im using right now was made in 2001. still dose every thing it did when i got it. actually better because i had vista on it and now i have xp tablet.</p><p>and i never owned a smart phone, i knew better, i used some ones else's and was discussed.</p><p>outdated hardware is by no means bad.</p>
<p>Cell phone would be my first thought</p>
<p>Hi, I am a beginner at making these things so my question may sound stupid; after the master on/off you split the positive wire to the led, amp, dc-dc and the voltmeter and you do this with the negative wires too but how do split these wires? And do you got any tips I must think of while making this speaker? thanks</p>
<p>from where did you get the grill</p>
I designed it myself on rhino and i've attached the cad file also in the instructables.
<p>how big does the back panel need to be?</p>
<p>The size of back panel is 33.4x16.9 cm. Even the grill size is same.</p>
<p>I'd highly recommend getting a Battery Tender Jr, or something similar, to charge your 12V batteries. Plugging them directly in to charge is not good for them (and can be dangerous to boot). </p>
<p>I have a 12V lead acid battery charger which has a transformer to supply the required 12V. It won't be connected directly to the power socket.</p>
Sorry didn't see the 12v battery charger in the list of supplies til just now. Nice build by the way! Love the look.
<p>Which Bluetooth receiver did you use? Could you please share the Amazon and / or manufacturer model &amp; part number? Thanks!</p>
<p>It was a generic chinese bluetooth receiver. I stay in India. I'm attaching one of the receiver available in USA.</p><p></p><p>http://www.amazon.com/Portable-Bluetooth-Receiver-Speakers-Headphones/dp/B00EUWRBH4/ref=pd_sim_422_1?ie=UTF8&amp;dpID=41qF9v40X-L&amp;dpSrc=sims&amp;preST=_AC_UL160_SR160%2C160_&amp;refRID=1KCS1HJ7NNHBPYRBP608</p>
<p>Nice work. I know you said that there is bass port tube calculation software available, did you use one or just 'trial and error'? Also did you test with a sealed box to see what the difference was? Thanks. </p>
<p>Thanks. I used the software to get the approximate port length. And the software gives the port length for a particular frequency. So, I had 3-4 tubes of varying length and I used them to see the difference and then went ahead with the one I liked. With the sealed box the bass was too much for my liking and it was making my back panel rattle a bit. So, I went ahead with ports.</p>
<p>Nice design. Reminds me a bit of the Marshall Stanmore speakers!</p>
<p>Thanks. Yeah, Marshall Stanmore was one of the speaker in the moodboard.</p>
Great post. Gave you a vote there
<p>Thank you so much. Glad you liked the post.</p>

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