Introduction: Bluetooth Battery Portable Speaker

As with most of my projects, the inspiration was borrowed and the final project is different then what I had originally planned. I started out with wanting to make an ammo can speaker. Unfortunately (actually fortunately), I didn't have a 50 cal case. My can was too small. I decided to use a plastic ammo can and it sounded like crap. Having purchased my supplies, I decided to build a wood box. And here we are. This speaker sounds really good and is capable of some surprisingly high output, and easily lasts a day. It can connect with any Bluetooth device at the push of a button.

This project takes basic carpentry and electronic skills including soldering. Nothing too hard or demanding. Except for the box, everything is off the shelf. And for you speaker builder's out there, I did not computer the enclosure volume. I also did not make separate left and right chambers. This was a quick build and serves my needs. I would not use this for critical listening but for streaming Bluetooth? It rocks. For those who want the best available, there are many online resources about speaker enclosure design and build.

Step 1: Supplies

Here is what I used:

Amp - Lepai LP - 2020a. Ebay $20

Speakers - Kenwood DFC1065 Amazon $18.81 (they were used). Any 4" car speaker will work. You should research and get one with the highest sensitivity. These are 90 db. 91 or 92 would be better.

IEC power connector $2.72. http://www.amazon.com/gp/product/B00917Z96S?psc=1&...

Power Switch $2.33. http://www.amazon.com/gp/product/B00MVN6WLU?psc=1&...

12v battery $20.79. http://www.amazon.com/gp/product/B0009GIKNE?psc=1&...

Volt Meter. $9.80. http://www.amazon.com/gp/product/B00CK3P20S?psc=1&...

Bluetooth Car Kit $18.99. http://www.amazon.com/gp/product/B00RSZWK1W?psc=1&...

12v to 5v module $2.99. http://www.amazon.com/gp/product/B00BMIVFK8?psc=1&...

Battery Charger $10.94. http://www.amazon.com/gp/product/B001G8AIMU?psc=1&...

Momentary Contact Button. Radio Shack. $3.99

Total price was around $100 + misc. hardware, parts (fuse), and paint.

Step 2: Build the Box

Sorry, no how to pictures here. This is a basic box. It was constructed of particle board. I would not recommend particle board but I knew I was going to finish with truck bed liner. You can finish with paint but you are going to spend a lot of time on the finish. If paint is were you are going, I would use MDF or birch (1/2").

You will need a saw and some sort of tool to make the cutouts (saber saw or router). You can always have the the lumber store (HD or Lowes) cut your box dimensions for you. Glue all of the pieces except the back.

The speakers should come with a template.

Step 3: Adding the Components

The only major obstacle I encountered was the Bluetooth receiver. My original design had a top that was easily opened. This box is sealed close. I needed a way to be able to trigger the pairing circuit. I took the Bluetooth apart and found that I could complete the circuit by soldering wire to each side of the micro switch. These are connected to a momentary contact switch. Need to pair? Push the button on the front. My soldering skills being what they are, I enclosed the connection with a dab of hot glue to hopefully add some strength. If I were to do it over again, I would have gone with a Bluetooth module instead of an already manufactured unit. Learning moment.

If that is a stumbling block, you could always mount the Bluetooth receiver on the exterior.

For the battery, I simply glued in extra wood to make a holder and used wire to hold in place. If you look at one of the battery supports, you will see 2 bolts. These are the power rails. 1 for positive, 1 for negative. There are many different ways to do this including just twisting all the wire together with wire nuts (I would not recommend).

For the smaller components, I just applied a bit of hot glue to hold them in place.

For the battery charger, I made a short cord from the power connector to a female plug and plugged the battery charger into that.

For the 12v to 5 module, ran 12v from the battery (via switch) to the module, then plugged the Bluetooth into the usb output.

The basic wiring goes something like this:

Speakers, left and right to the left and right terminals on the amp. I tinned these because it's the anal thing to do.

With the exception of the battery charger, all the electrical components are wired to the bolts. The positive from the battery passes through the switch to feed the positive bolt. The battery charger is wired directly to the battery so it can be charged when the speaker is turned off.

NOTE: make sure you fuse the positive to your battery. Just saying.

Step 4: Finishing Touches

I placed rubber feet on the bottom. The back is removable. There is a handle on top for transportation.

Since the amp controls are in the box, you will probably have to open and close it a few times to get things set just right. I am running volume around 70% with a touch of bass and treble. My audio app on my phone has a equalizer for fine tuning.

Enjoy.

Comments

author
philip_phiz07 (author)2016-10-02

i love how you didn't even go through the steps of the wiring

author
dnibeck (author)philip_phiz072016-10-03

Basic wiring was included. I later attached a more detailed though basic wiring diagram. I did not give steps of building the box, painting, or how to be a nice person. If you have a specific question(s), please ask - nicely. If you just wanted to be not nice (see be nice policy), then you have succeeded, well done!

author
FlavioV (author)2016-06-28

Hi! What's the speakers impedance? Somebody told me that, for a bluetooth system, should be 6 or 8 ohms tops, otherwise the circuit could burn. By the way, nice project!

author
dnibeck (author)FlavioV2016-06-28

Simplistic reply: They are 4 ohm. 8 ohm might be easier on the amp and perhaps extend battery life (which is already amazing). But I have not suffered any ill effects using the 4 ohm.

As for amp damage? This amp was designed to drive down to 2 ohm, so no real concerns there.

Thanks for the compliment. I get a lot of "please build me one" requests.

author
bhalliday (author)2016-01-15

your enclosure looks great what are the overall dimensions?

author
dnibeck (author)bhalliday2016-01-15

8h x 14w x 9d

author
dnibeck (author)2015-08-18

Here are two close ups from the inside.

0818151151a_HDR.jpg0818151151_HDR.jpg
author
DIY Hacks and How Tos (author)2015-08-15

This looks great.

author

Good job! I am looking for a similar idea this time. Can you submit a sketch of the wiring? It might help much users for understanding the electric circuit. Btw what fuse did you use? Are the knobs for volume etc inside the enclosure? My idea would be to unsolder the potentiometers and let them lead through the case while connect the leads with cable to the amp.

author
dnibeck (author)lathe_makeatio2015-08-18

I used an inline auto style fuse similar to this: https://www.fruugo.us/radioshack-automotive-inline...

I left the knobs inside treating the amp as just that, an amp. Volume is controlled via device feeding Bluetooth signal. I did this to keep the box sealed. I am working on a companion portable sub woofer that will have an external volume control. I haven't work that out yet as I would want to keep the speaker enclosure sealed.

I have attached a pour example of a wiring diagram but it goes something like this: Positive leads and negative leads from all accessories (amp, volt meter, 12v to 5v module) are tied together. This can be with a wire nut, rail, or post which is how I did it. The battery positive goes through the fuse to the switch. The switch out to the positive post. My switch has three connections as it is illuminated. One of these goes to the negative post for the lamp. The switch I used has 2 chrome connectors (positive switch) and 1 gold connector, that's the negative.

The battery negative goes to the negative post.

The battery charger (on 120v): the positive goes between the fuse and switch. This provides fuse protection but does not require the switch to be on to charge. The negative goes directly to the negative battery. Hope this makes sense.

circuit.pdf
author
Robin PJ (author)2015-08-18

Nice job

author
Saiyam (author)2015-08-15

The speakers look great! You can easily make out that they sound great as well.

author
dnibeck (author)Saiyam2015-08-16

Thanks