Ammo Box Speaker (with Bluetooth)




About: I've always liked pulling things apart - it's the putting back together again that I have some issues with.

There are plenty of ammo box speakers out there, this is my version I came up with. The build is relativity simple and only needs some basic skills and tools. You can actually make an even simpler version of this and I will go through how to do that as well.

The speaker uses a cheap amplifier purchased in eBay for $12 as well as a blue tooth module and a couple of speakers salvaged from a surround sound system. I tried to keep the cost down on this build as much as possible and used recycled parts where I could.

To give it some personality and turn it into a mean looking mofo, I added skull knobs and skull speaker covers


Step 1: Parts and Tools


1. Amp - eBay

2. 2 x speakers. You can buy them on eBay or just salvage from a car or surround sound system.

3. 2 x computer fan covers. eBay

4. Knobs - eBay

5. 12 battery - I used this one Century PS1280. You just need a 12v battery that will fit into the ammo box so use anything cheap that you can find

6. Ammo box. You can get these on eBay or just visit your local army surplus store

7. Bluetooth module - eBay

8. 12v to 5v converter - eBay

9. A bunch of speaker wire and other wires as necessary

10. 40mm vent cover - eBay

11. 20mm PVC coupling

12. Copper tubing (8mm)

13. Self tapping screws

14. Various nuts and bolts

15. on/off switch - eBay


1. Jigsaw

2. Hot glue

3. Soldering iron

4. Drill and various bits

5. Various screwdrivers etc

6. Files

Step 2: Scavenging the Speakers

As mentioned earlier in the 'ible, I decided to use some scavenged speakers from a surround sound system. Initially though I went with some speakers I had lying around but decided against it. You will see some of the images are from the original speakers I used throughout the 'ible.


1. Scavenge the speakers and remove from the cowling.

2. De-solder any wires that may be attached top the speakers.

Step 3: Cutting the Speaker Holes


1. Mark out on the ammo box the diameter of the speakers

2. Drill a hole inside the circle to enable the jigsaw blade to fit through

3. Using the jigsaw, carefully cut out the speaker inserts. Take your time with this as you will need to slowly turn the box as you cut the holes out.

4. Lastly file the edges and remove any burrs.

Step 4: Pull Apart the Amp

The amp that I chose to use can be picked-up for very cheap on eBay. I've used them before and they work great. Plus they are easy to pull apart.


1. Take off the knobs

2. Remove the small bolts that are around the pots

3. remove the cowling by un-screwing the screws on the bottom and on the back

4. Carefully pull out the circuit board. You might need to give it a wiggle to get it out

Step 5: Attaching a Toggle Switch

If you wanted to keep it as simple as possible, then you could just use the push switch that come with the amp. I wanted to have something a little hardier (and chunkier) so went with a large toggle switch.


1. Solder a couple of wires to the terminals on the toggle switch

2. Next solder the ends of the wires to the switch terminals on the circuit board. You could remove the switch on the board if you wanted to - I didn't see any need though.

3. You will also need to add the bluetooth module as well to the switch but I will go through that a little later. I have also included a schematic on this page which will hopefully help

Step 6: Attaching the Amp to the Ammo Box

Making sure that you drill the holes in the right places obviously is important. A little off and the amp won't line-up correctly. There is however an easy way to do this. Just lay a piece of masking tape across the 3 pots on the amp, mark where the ends touch the masking tape, and stick to the ammo lid. Now when you drill you can be certain that the pots will line up correctly.


1. I decided to attach the amp to the lid of the ammo box. It made it easy to get to and also easy to attach. You could try and put the amp on the bottom of the ammo box but it makes it hard to attach the power plug, speaker wires etc. Drill the holes for the pots (volume controls) and switch

3. You can easily remove the lid on the ammo box by opening fully and pushing it to the left. The lid will then come out of it's hinges.

4. Push the pots through the holes and attach the amp by replacing the bolts onto the pots. This is enough to hold the amp in place.

5. Attach the on/off toggle switch

Step 7: Adding a Heat-Sink

After attaching the amp I realized that the cowling acts as a heat-sink. I decided to add one that I had lying around. You could probably get away without attaching one, depending on what type of battery you hook the amp up to. I thought it was better safe than sorry though.


1. There were 2 screw holes already on the board so |I just used these to attach the heat-sink. Measure and drill a couple holes on the heat-sink so you can attach it to the circuit board

2. I had to make the holes on the board a little bigger so just used the drill again on these

3. Attach the heat-sink with a small bolt and nut.

Step 8: Attaching the Knobs


1. The knobs that I used were too small to fit onto the pot ends. You will need to make these a little larger by drilling them out. Make sure that they are still a tight fit though.

2. Add a little super glue to the hole in the knob and push onto the pots. Leave this to dry for 20 minutes.

Step 9: Adding the Battery


1. To enable the battery to be charged, you will need to add a female socket. Drill a hole in the side of the ammo box large enough for the socket to fit into.

2. Place the socket in the hole and screw into place

3. Solder 2 wires to the terminals on the socket and then attach to the wires on the battery.

4. To power the amp, you will need to also attach a male jack to the battery. Solder some wires to the male jack and attach them to the same terminals that you added the battery to. Make sure that you make the wires long enough to be able to plug into the amp when the lid of the ammo box is open

Step 10: Attaching the Speakers to the Ammo Box


1. To ensure the speaker don't vibrate against the ammo box, it's best to add some padding on the inside of the sections that will touch the ammo box. I used sticky sided foam and cut to fit.

2. Place the speakers into the holes in the ammo box

3. To secure the speaker to the ammo box I used some self tapping screws. Drill the holes and screw into place.

Step 11: Adding the Speaker Protectors

To make sure that the speaker protectors are a distance away from the speakers (you don't want them touching the actual speakers) you will need to make some bushes. I used copper tubing to make these but you could just use washers or nuts or whatever else you have around.


1. With a tube cutter, cut 8 equal pieces of copper tubing

2. Place the protectors on the speaker and mark where you will need to drill the holes. once you are happy with the position, start drilling

3. Attach the protectors to the ammo box using screws and the bushes.

Step 12: Bring the Bass

I decided to add a port to allow equalization of the pressure between the inside and outside of the ammo box. The box is very well sealed and I didn't want to add undue pressure to the speakers diaphragm. Plus I wanted to get as much bass out of it as possible and adding a port helps with this.


1. make a hole in between the 2 speakers. I just drilled around the hole and cut away the piece of metal. I then filed the edges smooth.

2. I also decided to add a 20mm PVC coupling to the hole. This will allow the air to be pulled from the middle of the ammo box (have no idea if this will be a benefit of not). If you do add the PVC coupling, then make sure the hole you make is the same size as the coupling.

3. Next screw into place a small fan shield. Not totally necessary but is good for ascetics.

3. Add some hot glue to the bottom of the coupling and glue it to the bottom of the ammo box with the end in the hole.

Step 13: Attaching the Bluetooth Module and Voltage Regulator

Attaching the module is quite simple really. All you need to do is to make sure that when you flick the main switch and turn the amp on, the m, the module also turns on.


1. Attach the black wire to one of the switch terminal

2. Attach the red wire from the regulator to the positive end of the battery. You can just solder this to the terminal on the female charging socket.

3. Next, attach another wire to the other switch terminal and attach this to the negative end of the battery. Again, you can just solder to the terminal on the female charging socket.

4. Lastly, it's time to attach the speaker wires, power jack and audio jack into the amp. Plug everything in and make sure it all works.



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    21 Discussions


    3 years ago

    Have you had any problems with interference from the Bluetooth module? I've made a couple of these and have never been able to crack this side of it. Lovely job by the way

    4 replies

    Reply 3 years ago

    If anyone did read this comment and is actually waiting for an answer to how the small bluetooth module/amp combo went I installed it recently.

    Since it appears links don't work, if you do a google search for "V0Z7 bluetooth" you should see plenty of ebay results for the little white board I bought.

    Firstly, quality and volume is decent running straight form a 18650 battery (less than the full 5v it can take), and there is zero extra noise/buzz from ground loop often associated with using a cheap bluetooth module. Highly reccomended for smaller bluetooth projects!!!


    Reply 3 years ago

    I had the same problem of humming with the Bluetooth. Just use a 12v DC to DC converter to isolate the ground of your USB power supply and it does the trick! They cost a couple of dollars and solves the problem.


    Reply 3 years ago

    I sometimes hear a high pitch sound that comes out of the speakers if the sound is right down. Once I turn the sound up it seems to disappear (prob being drowned out by the music). Maybe a better bluetooth module might help remove any interference? Also, I was thinking of locating the bluetooth module outside the box. It would then just plug into the 5V regulator which could also be used to charge your phone!


    Reply 3 years ago

    I have also gone on this endeavour and had real problems with the dreaded bluetooth buzz and 'signal sounds'. They can really ruin your listening experience, and sour the DIY journey.

    What have you tried so far? This problem is usually caused by a ground loop when you connect the bluetooth module and the amp to the same power source.

    If you're keen to salvage one of your current projects and haven't already tried this, try buying an audio ground loop isolator off ebay (or somewhere similar). You should be able to get one you can just pass your 3.5mm or RCA cables straight through. Perhaps try putting the ground loop isolator both between the amp and bluetooth module, as well as between the amp and the speakers if that's possible and see what gives you your best result... But I would not expect this to eliminate all noise.

    A second option is to buy a bluetooth module with this ground loop/noise isolation built in. Obviously it depends on the size of you project, but for 12v applications I can't recommend the Sure APT-X Bluetooth board ( enough. There is absolutely no 'buzz' when using this board, and through digital signal processing and the high quality APT-X codec the sound it produces (at least to my ear) is better than the original mp3 through an Aux line-in. It costs a bit more than most cheapy Chinese shitty job modules, but the difference in both build quality and sound quality is night and day. You won't regret buying this if it suits the purposes of your project.

    For smaller projects, I think an amplifier board that contains a bluetooth module as well is likely a better bet for noise isolation/reduction, but I just don't know - I'm currently in the process of testing this. I have recently ordered this module ( for a small portable speaker. It's a 3W per channel 5v amplifier with bluetooth built-in. I will try and remember to post here when I receive and have a chance to test this board.

    Hope that helps, but feel free to ask me further questions or clarify something.


    3 years ago

    Wow does that look epic! I wish I had one xD


    3 years ago

    really cool project
    i imtend on making one soon if time and resources allow

    when you found the skull knobs were there anyother designes avaible
    thanks heaps


    3 years ago

    How long does the battery usually last? I have been wanting to make one of these as a gift. But battery life is my biggest concern

    Nice write up too

    2 replies

    Reply 3 years ago


    The battery I used has been sitting my shed for sometime so doesn't hold power as good as it used to. Saying that, it still lasts for about 6 hours which is plenty. I will probably invest in a new battery soon. The amps don't draw on the amps too hard so a good battery should last for quite a long time without charging


    Reply 3 years ago

    Do you have anything to prevent over-charging or over-discharging of the battery or are you just guessing?

    SLA batteries are potentially dangerous when over-charged, and over discharging is an extremely good way to kill a battery.


    3 years ago

    This looks awesome. Is the sound quality pretty decent?

    3 replies

    Reply 3 years ago

    Hi Lord ii

    the sounds great! what sound you do get out of the ammo box will depend ion the speakers that you use. The ones I used (scavenged from a pair of surround sound speakers) can handle the volume nearly to max. You start to get some distortion if the bass is turned up too high though.

    Jockywilson11 lonesoulsurfer

    Reply 3 years ago

    I used a Mini bluetooth amp that has no interference when I made mine


    Reply 3 years ago

    Just finishing up building one myself! I found bass distortion can be improved by applying hot glue around the edge of the speakers to muffle vibration between them and the case. It can look a bit scruff if you're not careful, but I think it's worth it for the sound quality and I think your fan covers would mask it pretty well.


    3 years ago

    Very nicely done! I like the little pot location trick; nifty!

    John T MacF Mood

    3 years ago

    Where did you end up placing the Bluetooth module in your final build? The Ammo Box is metal, and effectively a Faraday cage. Perhaps the speaker holes will allow signal to the Bluetooth receiver from the correct angle.

    1 reply

    hey John

    Yeah it's inside the ammo box. Thought the same thing initially but it works fine. You probably right about the signal being able to detect due to holes, especially the port hole in the bottom