Introduction: Ammo Box Speakers

Picture of Ammo Box Speakers

Hi all! As the title suggests I'm doing this instructible on ammo box speakers!  I came across this instructible > a good few months ago now, and this gave me all the ideas/concepts/designs to give me courage to build my own. I suggest you check out that instructible first just in case i miss anything out (the comments were especially helpful!) :)

I thought I'd tell you a little bit about myself as this is my first instructible. 
Name :- William Roberts
Age :- 18
Bio:- I am a student currently studying Design and technology: graphics products, physics, maths and geology. I absolutely love DIY ideas and i am very appreciative of design influences. I love the great outdoors and i regularly participate in sports. I also love the occasional extreme sport (mountain boarding most notably). Live in the UK, you could probably guess that since i quote everything in £.

well now that introduction is out of the way i'll get on to the 'ible! 

Step 1: Parts and Tools

Picture of Parts and Tools

On this build i wanted to keep the costs as low as possible but without sacrificing quality. To get it as cheap as possible this meant shopping around on the internet (Ebay especially!). Due to keeping costs down i did buy some stuff from China so this greatly increased waiting time in order to build. so, on with the parts list!

1) Ammo box - £12.73 (Ebay, price has gone up)
2) Speakers - £28.99 (incarconnections)
3) Battery pack - £2
4) Mini 12v amp- cost me £2.50 in an auction from this seller 
5)Panel mount 3.5mm jack- £2.48
6)Rubber feet - £1.78
7)3.5mm to 3.5mm jack - £1.98
8)Batteries! (wouldn't get far without these!) bought at Cost-Co pack of 48 for about £5
9) on/off switch - £3.84
10) Panel mount Female DC connector - £1.38 (ebay)
11) DC connectors (ebay) £1.48 x2 -

Total= £65.64 (with loads of extra batteries!)

Additional items (improvements)
12v deep cycle battery 9Ah - (ebay) £17
12v battery charger
(just a cheap one) - £7.90 -
Some decent wire £1 (1m). 
spade connectors £1 for 10 (local store)

extra £26.90

(i could have reduced cost by using cheaper speakers or getting the right battery to start with)

Tools used

1) Cordless drill with appropriate drill bits (2,3,10mm metal drill bits)
2) Jigsaw
3) Round metal file
4) Scissors (wire strippers would be better!)
5) Electrical tape
6) Towel (not nessesary, just used to protect table)
7) Quick-grip bar clamp
8) Small flat head and Phillips screw drivers
9) Bit of wood (see later)
10)  Hand saw
11) EAR AND EYE PROTECTION. This is vital! I started cutting without these and i got hit around my eye multiple times from metal fragments. And the noise is deafening. You've been warned.
12) Compass (for marking out)
13) Pencil/marker pen (or even a nail, works just the same)
14) Dustpan and brush!
15)  rotary tool (Dremel) with grinding tool to remove some burrs

Things I should of used
1) Wire strippers
2) Soldering iron and solder
3) Spot light (or just better lighting in general)
4) 20mm metal hole borer (would have been a lot easier and neater)

Step 2: Preparation

Picture of Preparation

Before i go into the main part of this instructible i'll just give you a rough time guide. All times will be slightly exaggerated ;)
1) Marking out - 10 min
2) Setting up - 20 min
3) Cutting and filing - 1hr 30 min (take your time on this!)
4) Circuitry - 30 min
5) Mounting - 15 min
6) Cleaning up - 20 min (I got metal filings EVERYWHERE! plus you need to put the tools away)
7) Testing - 999999999999 min (well maybe not, but you need to give plenty of time to admire your work :) )

Obviously some people will do this quicker than others so don't take these times as set guidelines. If you do it slower who cares, you'll still get there in the end!

So here we go!

Marking out

The way i did this was... placed the speaker grills where i wanted them, traced the outline in pencil, found the middle using the compass, center punched the middle, set the compass to 93mm (size of speaker mounting hole) then draw the 93mm circle. This will give you the hole you need to cut. For the on/off switch, 3.5mm jack and external power just draw the circles you need to cut out in the appropriate place.

Step 3: Wiring

Picture of Wiring

My knowledge of electronics is very limited so i did refer to Google quite a few times!
I thought this would be the hardest part due to my lack of electrical knowledge but this was the easy part! As you can see from my parts list I've gone for easy connectors (screw terminals and crimp connectors) as my soldering iron broke and gave me a nasty electric shock last time i used it.

Parts needed 

Battery pack
on/off switch

Mini amp
Small amount of electrical cable (I just cut some off the battery pack)
Panel mount 3.5mm jack
3.5mm to 3.5mm jack

Just to be safe (to test the system)
Speakers and speaker cable 
mp3/phone for music

This part is best shown with pictures.

Step 4: Cutting

Picture of Cutting

This is by far the longest process. Make sure you have all your tools ready for this step.
Make sure you wear eye and ear protection!
support the box with a bit of wood (see pictures).

Drill a starter hole, then jigsaw your way around the markings.

Step 5: Mounting

Picture of Mounting

There's not much to say with this really, just follow the instructions on the speakers and use your common sense!
I still haven't secured my amp to anything because i don't know where to put it but it seems to be fine loose in the box.

Step 6: Turning Up the Volume!

Picture of Turning Up the Volume!

The fun part! Just don't do this late at night ;) Pick out your favourite song, plug the mp3 player in, turn speaker on (make sure lid is closed) and press play! Don't put it on full volume straight away! gradually increase... Enjoy! :)

Easily fills a sports hall with music! I even use it instead of my home stereo system!

Step 7: Overview

Picture of Overview

Ok so I've thoroughly tested this and these are my findings.
Firstly, i never needed to buy the AA battery pack. The 12V sealed battery i replaced these with lasts 75 hours (being played at 60% volume)! For all the people who think that is a crazy amount of time, it is. Your standard electrical equations do not work with this system because of the deep cycle battery. Using some basic formulae (V=IR , P=VI etc...) i worked out that they should only run about 15 hours when being played at 25% volume. After doing some research into this I found out about the Peukert effect. Honestly i still don't fully understand it (not even my physics lecturer could), but if anyone could explain it well then let me know!
Charge time is roughly 8 hours.

Secondly, this weighs a tonne ( well not quite). So don't drop it ( i have on multiple occasions and there is a few dents to show for it) the battery itself weighs about 2.7kg.

Thirdly, there seems to be some feedback in the system (but only when i plug a 3.5mm in) I think it could be that the cable is cheap but i'm open to suggestions!

lastly, don't bother screwing around with a bass port. It sounds SO much better closed.

If you want any more detail or if i have any mistakes just comment below! Thanks for looking! and if you wouldn't mind voting for me i wouldn't say no ;)

I did try a Lepai amp in this set up but it drew too much power. It would only last around 18 hours on a full charge! the Lepai is a lovely amp but not for me.
The paracord handle makes it nice to carry and i think it makes it look better.
I have considered painting it, but i love the original look too much!
I have also considered a folding solar panel (in the process of testing it on a smaller scale (only 5v)). So depending on how that goes, i may end up charging from solar!
I did use this system with the AA battery pack i bought but the battery life was only 2 hours when being played at 50% volume. Pretty disappointing considering the deep cycle battery lasts 75 hours easily.


lifeinbeats (author)2013-08-16

I'd say it weighs close to 20 lbs. Maybe a little less. Not sure how many kgs that is. If you look at my wiring diagram, I've worked in a jack on the case that goes to the batteries. I then replaced the tip on the battery charger cord with a male connector that fits the jack. It's the panel mounted jack below the switch in the pictures if that helps.

Here are some finalized shots.

scotprice (author)lifeinbeats2014-06-18

I know it has been a while since you made this, but I was wondering if you have any pictures/diagrams of how you wired the switch together? I saw your wiring diagram, but I can figure out how you wired the six post of the switch together so that it switches between battery power, and wall power.

WillERoberts (author)lifeinbeats2013-08-17

i love the way you wrapped the handle, might do something similar on mine!
underneath the 2 handles is that just a bumper to stop the handles getting hit? or is it a port?

lifeinbeats (author)WillERoberts2013-08-17

The two handles hold my iPhone and the bumper is so that the phone doesn't fall through. There's probably a better way to do this. If I could do it again I would probably use metal handles and distance them far enough apart so that you can still work the phone while its in there. So basically on the very top and very bottom of the phone.

WillERoberts (author)lifeinbeats2013-08-17

ah ok! can you lift the box by those handles?

lifeinbeats (author)WillERoberts2013-08-17

I probably could but I wouldn't expect it to hold. They're just cheapo plastic cabinet handles with a screw on each end. I much prefer the para cord wrapped handle as u recommended ; )

lifeinbeats (author)2013-08-15

Finito! Mostly... I still haven't tried adding USB to the mix, but I'm kind of hesitant since the little charging module I got was only $.99 at Target. But other than that... Finito!

I ended up adding a place to put my Iphone while it's playing. I conveniently found some plastic drawer handles that fit my phone perfectly at a local hardware store for $1 each. Then glued a little rubber foot at the bottom so the phone doesn't fall through. It looks decent. If I could do it again though, I'd probably spend the extra $3 and get metal handles. The spray paint on these comes off easily when I bump the box on anything.

I also cannibalized a pillow that I wasn't using for it's polyfill (polyester fiber fill). As WillERoberts mentioned, the largish batteries I used took up a lot of the space in the box. The theory behind the polyfill is that it can trick your speaker into thinking the box is up to 40% bigger by slowing the air movement down. Not sure the specifics, but I think even with an empty 50 cal ammo box, you'd probably want this stuff. The calculations I did (see comments below) seemed as though you'd want a larger airspace for two 4.5" speakers.

At first when I installed the polyfill, it actually sounded worse. The key to this is that if you pack the polyfill too tightly, it can actually have the opposite effect. So I took some of it out, and whala. A lot more bass, noticeable instantly.

For the connections on the outside, I pretty much followed my wiring diagram. I've got a DPDT switch with an On-Off-On configuration. I read that the 12V battery chargers can actually harm components if plugged while you're running off the batteries. The reason for this is that batteries are fine at higher voltages when being charged, where electronics are usually not. So when the battery is dead, the charger might spike at 14-15V. So the DPDT switch has 3 positions:
- On-1: Battery is connected to the amp.
- On-2: 12v power supply is connected to the amp
- Off: All power to the amp is cut off. This is the ideal position for the charger to be plugged in (and is my fail safe. I don't technically NEED this position. You could charge the batter in On-2 position, but I didn't want to risk forgetting which side was which).

So, on the side of the box you've got your switch, your headphone female panel mount connector, and two dc adapter connectors, one for the charger and one for the amp power supply. Note that I had to replace the tip on the end of my Battery Tender Junior so I could mount the jack on the side of the box. If you're ok with opening the lid to plug stuff in, you could easily forget this step.

In order to achieve a rattle-free design, I bought a cheap roll of door/window weatherstripping. It's not really it's intended design, but it works like a charm. I also glued in some metal L brackets to keep the amp and the batteries in place. Theoretically, after you put in the polyfill, these things shouldn't move around too much, but the batteries are heavy and I didn't want to chance it.

And speaking of rattling, I wrapped the handle in paracord like WillERoberts instructed. This makes it comfortable holding this thing (especially with the weight) but it also prevents the handle from rattling like crazy, which is will be prone to do.

Thanks for the 'Ible WillERoberts! I had a lot of fun doing this and it came out great!!!

WillERoberts (author)lifeinbeats2013-08-15

Looks great! how much does it weigh? with 2 batteries i guess it's close to 5 kg?
when you charge your battery do you connect the charger straight to the battery terminals or have i missed something?

lifeinbeats (author)2013-07-19

Another update. I might be taking this a little far... but it's certainly fun. So I made a wiring diagram that might help if anyone else wants to do this.

I decided not to go with a bluetooth module. Didn't want to add the complexity of switching back and forth between headphone in and bluetooth.

I did add a 7 amp fuse (I upgraded the power supply on my lepai 2020 to a 6 amp model, which was recommended in many forums). If you decide to add a fuse, make sure you get the right amperage. The volt rating on the fuse doesn't matter. You can't even really find fuses rated at 12v (I don't think). So using 125v fuse is fine.

I wanted this to be a nice clean build, with everything you need on the outside of the box. This adds a lot of complexity, but it's not too expensive.

The DPDT power switch is called an on-off-on type. Which means when I'm all said and done, it will switch from battery power to wall power and have a totally off position in between.

The usb  that I'm thinking of getting isn't exactly panel mount, but it will do, and it's really cheap. I'm just going to wire the power to the two leads, and it will convert the 12v to 5v for the usb. It looks like if you take off the cover, too, you could drill a large hole in your box and essentially panel mount it. For about 10, you can get something more legit, but I thought this would save a few bucks. Click here to see the one I'm using.

In addition to the usb and rocker switch, on the outside of the box will be:
    - a panel mounted DC jack for the Battery Tender Junior 12v charger
    - a panel mounted DC jack for the amp power supply
    - a panel mounted 3.5mm headphone jack

I was originally going to try to squeeze two 9 amp hour batteries into this little box, but after some research, it looks like 10 amp hours is going to be more than sufficient. If you want to do your own calculations, consider that 4-6 watts per speaker is actually a lot of sound. So if we assume 5 watts per speaker, 10 total, with a 12v battery the equation looks like Watts=amps x voltage so we get about .833 amps. That roughly equates to about 12 hours on a single charge, which was more than enough for my purposes. Click here to see the batteries I'm going to get.

In terms of the mounting in the box, I could just glue everything down. Totally fine way to go. I am OCD though and wanted to have the "option" to remove thing if I needed to. So here's what I was thinking. I'm going to get some little simple steel angles. The orange ones I will drill and attach to the bottom of the box, since the bolts will be hidden. The others (pink) I will glue on with some J&B weld. That stuff is seriously amazing. In theory, if you remove the bolt on the centermost angle on the batteries (assuming that the amp is removed first) you can slide it out far enough from the far angle to remove it. Kind of confusing but if you look at my photo you can probably make sense of it.

Two more angles will mount the amp. They'll glue on the box and then will bolt to the amp mounts. On the other side I will just glue on some sort of metal rod to the case (green). This will only work for the Lepai 2020a+ amp though. If yours is smaller you probably won't have any problems putting it anywhere.

Hope that helps. I'll post final images once I get the batteries and get everything mounted.

WillERoberts (author)lifeinbeats2013-07-20
You will need to enter a value between 1.3 and 1.4 for the Peukert number becasue you are using lead acid batteries. If your amp is taking 6A then your speakers should last less than an hour.

WillERoberts (author)lifeinbeats2013-07-20

You. Are. Amazing!
I admire the effort you are putting into this! just a few little comments.
Do you have a link for upgrading the amp? And regarding your run time calculations. You will need to take into account the Peukert effect. I only just about understand it myself so i suggest you look at this page . Wikipedia is also quite helpful.
Your mounting technique is genius! At the moment I am using superglue and velcro to hold the battery in place so I may look at some sort of bracket.
Final question. With your DC battery charger jack, because it is charging 2 batteries, would you need to increase the current that the battery charger provides? Or should you put a blocking diode between both batteries and the charger jack to stop a possible discharge? My battery charger only provides 500mA, so if you are charging 2 batteries it would provide 250mA per battery which may not be enough to charge the battery. What battery charger will you be using?
Thanks for keeping us updated! Cannot wait to see the end product!

lifeinbeats (author)2013-07-09

Wanted to update people with my progress. So far I've planned my unit out and bought the ammo box and the speakers. I found a nice pair of 4" coaxial Polk Audio that should produce some nice sound from this little guy. After doing some research, it looks like you're never going to get much bass from a 4" speaker, but these should help.

I'm also planning on using a Lepai 2020a+ amp. It's 20W per channel and has great reviews. If you beef up the power supply to a 4-5 amp 12v unit, it also improves the sound. I'm going to try to panel mount the unit on the back side of the box. This will effectively allow me to control volume and power straight from the faceplate (and it's pretty slick looking).

I had a tough time finding a large enough capacity battery that would fit in a 50 cal box, until I remembered that I can do the batteries in parallel. So, the plan is to get 2 UB1290 batteries (they actually come in a 2 pack for around $40) for a combined capacity of about 18mah. Hopefully that will offset the increased power draw from the Lepai mini amp. I'm planning on placing each battery on it's side on either end of the unit. This is the only way they would fit, but it also has the added advantage of distributing the weight a little more evenly. See attached image. If you'd like my sketchup model to play around with sizing, let me know.

A few other mods I'm planning are as follows:

- Going to put two panel mount DC terminals on the outside of the box. One to charge the batteries and one to power the amp when I don't want to use the battery. I did some research and it sounded like I MIGHT be ok to just charge the battery during use, effectively negating the need to plug the amp in, but it was questionable. The 12v battery chargers (going to use the Battery Tender Junior) kick up the voltage a little bit when the battery is low, and if you're drawing off the battery for the amp while it's doing that, it will drop the voltage and has the potential to damage something. Since this is an issue, and to make it dummy proof, I'm going to install a DPST (had to research that one) rocker switch, so that the amp either draws from the battery (portable mode) or it draws from the wall socket. To note: I don't think you'll be able to charge the battery AND power the amp from the same wall socket and transformer, without some serious knowledge of electronics.

- Going to try to integrate a usb charger into the mix as suggested by another user. It sounded like this might cause some additional feedback into the system, but it's unclear. I'm going to test it out and if it doesn't seem to be causing any issues, I want to panel mount a usb terminal on the outside of the box (to keep everything clean). It looks like that's going to be harder than it sounds though. I'll probably need to take apart a 12v usb cigarette lighter charger, and then buy an extension/panel mount usb cord and plug it into that.

- I'd like to experiment with a bluetooth receiver but I'm not sure how that would work. I would like everything to be clean and functional from the outside of the box, but the mini amps only tend to have on input, meaning you would either have to choose between bluetooth or hardwired, OR you would have to reach in the box and swap out the cables when you wanted to switch. Theoretically, you could do a toggle switch. But each channel (left and right) has two cables, so you would need a switch with a lot of inputs. Maybe a DPDT?

I'll try to post the finished product as soon as I'm done. Waiting for my next paycheck to buy the batteries and the amp.

WillERoberts (author)lifeinbeats2013-07-09

Sounds like you are set! I love the idea of using a DPST switch (although i think you might mean a SPDT switch)! I may add one to my design when i have time!

My only concern is that you might be filling the box too much. The main reason speakers go inside a box is for the sound to amplify and to give it more bass, but by using 2 batteries and a fairly large amp you will have little to no space for the sound to travel which may result in a 'tinny' sound.

Oh, and with your reasoning behind using 2 batteries (to increase run time when using the amp) you should get around 45 hours, Which is pretty good. But don't forget those batteries weigh around 2.65kg each! so you are looking at a total weight (with everything) of around 8kg! quite a hefty speaker!

Cannot wait to see the end product though! Be sure to post it here!

(and that reminds me, i need to create a video of mine in action...)

lifeinbeats (author)WillERoberts2013-07-09

I think actually I mean DPDT switch (so confusing). I could be wrong though. Since there is a positive and negative pair coming from the battery and from the DC in, and then pos and neg out to the amp, I think I need 6 contacts in total, with the switch going back and forth between the two pairs. I found this good resource that explains switches in case anyone else is reading this and is interested:

I'm glad you commented on the box size, since I hadn't really looked into that at all. I figured that since these were made for a car, that it didn't really matter if there was a cavity behind them (assuming that they would throw most of the sound outwards). I found this site though:
that does a nice job of explaining speaker basics. It would seem that if the speakers have open backs on them, they're made to utilize the amount of air in the cavity behind them. Oddly enough, my little 4 inchers do have open backs. Surprising since they're obviously made to mount in a door, but we'll see. The large amp really wants to be mounted in the center of the case, to utilize the space between the backs of the speakers. I've also tried a bunch of other configurations, and the length of the amp makes it so that you have to put the battery on one side or the other (if using one) which would really offset the balance. I might try it this way, and if it doesn't work out, I can always get a smaller battery. You could help me test it by stuffing a shirt in your box and seeing if there's any difference in sound ; )

On another topic, do you have any ideas on a clean way to keep everything in place inside the box? It'd be nice if I didn't have to glue things in there, in case I ever need to take them out. But I also don't want to put a bunch of holes through the box and have bolts sticking out everywhere... I'm at a loss.

WillERoberts (author)lifeinbeats2013-07-10

OK, i tried stuffing a shirt in the box and these are my results.

closed lid - At low volumes no difference but at high volumes the bass seems a little muffled.

open lid - It helps to give more bass at all volumes.

But you need to remember that a shirt is totally different to an extra battery due to its material. The shirt acts like sound deadening foam while a battery will reflect the sound waves.

Currently i am using some high density packaging foam to keep the amp in place. I just wedge a sticks of the foam between the sides of the box and put the amp in between them. Doesn't look pretty but it works well. Other than that all other mounting method would require glue or screws of some kind. If you do find a solution let me know!

Keith231105 (author)2016-03-28

Question, i am getting little to no audio out of my speakers even with both tbe amp and phone volume maxed out. Any ideas. Im pretty electronically inept so any and all suggestions are great.

mfroese (author)2016-01-29

I would have put a solar panel on top to charge the batteries.

patmcurtis made it! (author)2014-12-27

cool build! We just started building these (and all our friends wanted them) so we started a small business manufacturing them several months ago, for those of you that are too lazy to build one :-) We use a CNC and missile switches to give the control panel a cool look, great rockford fosgate 4" drivers, and an MDF to really give us beautiful sound. The Bluetooth was a pain in the ass, but with the right positioning inside the can we get great range now (also threw in a monster 12v battery and 2 USBs)! Would love your feedback - we're at Thanks guys! - Patrick

ChrisO5 (author)patmcurtis2015-01-11

So all inputs, outputs, and switches are contained inside the box on that panel?

patmcurtis (author)ChrisO52015-01-11

Chris, that's correct. In our testing, we found the sound to be even better when you close the lid...and that creates a nice compartment to hold your wallet, phone, glasses, etc when you're out and about at the beach, bbq, camping, pool.

We also used a Fat 50, because all of the testing we did, the regular 50 cal didn't have enough air space in the container to get a good sound (for the 4" fosgates). They are a bit more expensive than the regular 50 cal cans which are more common, but the difference was pretty noticeable. Amazing what a little more space will do! :-)

ChrisO5 (author)patmcurtis2015-01-12

If you don't mind me asking, what kind of amp do you guys use?

jmcdonald23 (author)2014-12-28

I just ordered the parts to make one of these but I'm adding in a bluetooth module.

jmcdonald23 (author)2014-12-28

I just ordered the parts to make one of these but I'm adding in a bluetooth module.

jmcdonald23 (author)2014-12-28

I just ordered the parts to make one of these but I'm adding in a bluetooth module.

jmcdonald23 (author)2014-12-28

I just ordered all the parts to make one of these but am adding a bluetooth module.

jmcdonald23 (author)2014-12-28

I just ordered parts to make one of these but I'm making it bluetooth capable. All you need to do is add in one of these and you have remote control plus still have your aux input as well as a few other features. Wouldn't be too hard to incorporate it into the design.

airmandunkel (author)2014-05-30

This is great! Have you thought about installing a battery charge indicator?

corn674 (author)2014-03-16

Now i have a question i built mine but want to have a way to charge my phone ive added a solar panel to mine so it charges the battery no power cord needed. But want to add a female usb plug to charge my iphone

Gambafreaks (author)2013-08-12

At final, I have choosen:
Sure 2x50W Class D Audio Amplifier  TDA7492 completely encapsuled

Sure Wireless Home Stereo Audio Bluetooth Music Receiver Ipod Iphone PC
Pioneer speaker 4" 30W RMS

Pictures updates of the project, holes cut with the help of a CNC!!

My main doubt came now, I have bought also a 19V 4.74A 90W Watt AC/DC Power Adapter and I don´t know exactly how to combine the 12v 7Ah battery with the power adaptor, I´d like the battery will be running until I will connect the power adaptor, then I´d like that battery will charge while the power adaptor gives current to the amp, both things at same time!

I have thought in two diodes but I think that using a relay would be better...

Problems!!  the AC/DC adaptor is up to 19V and the battery is 12V I think I´d must to use a DC booster 19/12V...

Help please!!

WillERoberts (author)Gambafreaks2013-08-12

The amp you have chosen has a power range of 14-27 volts, so your battery will not be able to power it directly. It may work, but you will not get anywhere near 50 watts.
If i was you i wouldn't combine the power supply and battery. when you charge a 12v battery you normally give it 15-16 volts but giving it 19v may be too much, but the 19v would be good to power the amp. You could possibly step up the voltage from the battery but this will decrease battery life. maybe add a simple joule thief?
I wish i had a CNC machine :(

Gambafreaks (author)2013-08-02

Can you recommend me another amplifier, Lepai is there, but more options?

I didn´t see any BT module with exterior antenna capability, options??

WillERoberts (author)Gambafreaks2013-08-02

with the Bluetooth you may have to take one apart and add an external antenna.
Lepai is probably your best bet, they are relatively cheap and give good sound.
You want an amp that draws less than 2A, so you can have a good battery life. Normally the better the amp the more Amps it will draw from your power supply.
good luck :)

Gambafreaks (author)2013-08-01

Hello guys, I´m from Spain and I'm trying to make a boombox like yours. This is my box: First of all, I´ve thought too the bluetooth module, but I think that it doesn´t work fine inside a thick metal box, so I´ll search an exterior antenna for this purpose, but I haven´t found nothing yet with that capability. In the picture you can see the exterior BT antenna

The BT modules I have looked without antenna are these: or

On the other hand, My box is this:

I don´t know what amplifier choose, if a Lepai, Sure 2x100W or anyone...

The rotary encoder:

And in this moments this is my schematic:

The speakers would probably be these:

Any suggestion??


WillERoberts (author)Gambafreaks2013-08-01

those amps have a very high current draw, maybe looking for something that draws less current or you will have a very low battery life. Otherwise just build it.
With the bluetooth module you may be able to take one apart and give it an external antenna.

lifeinbeats (author)2013-07-02

Also, any thoughts on the feedback you were experiencing? I would imagine its interference from the power source but that's just an uneducated guess. Anyone have any luck filtering the feedback?

WillERoberts (author)lifeinbeats2013-07-02

I don't think it is the power source as i get the same thing when using power from the battery or the wall plug. I think it may be due to cheap wiring but to test that theory I need to get some decent electric/audio cable which does cost a bit.
Just a bit more information regarding the feedback, it doesn't give any feedback when i reach the end of an album/playlist BUT if i pause the music i do get feedback.

lifeinbeats (author)2013-07-02

Awesome instructables. I think I'm going to give it a go. Can you post the rough outer dimensions of the ammo box you found? There are a lot for sale here in the US for cheap, but they are all different sizes.

WillERoberts (author)lifeinbeats2013-07-02

L 11.5" X w 6" X h 7"
If you ask for a .50 cal ammo box they should know what you mean.

samnjari (author)2013-06-24

thank you for that

WillERoberts (author)samnjari2013-06-25

No problem :)

billgeo (author)2013-06-24

Great build...

Also, some ideas:

1) Fill the inside with sound absorbent material,
like Polyurethane Acoustical Foam or Rockwool

2) Use a bluetooth module to transmit audio from the ipod to the boombox

WillERoberts (author)billgeo2013-06-25

Thank you!
Bluetooth will be added over the coming months hopefully, but I've decided against acoustic foam because i like to carry items in the can and using foam would mean i have less space in the can.

jonkun227 (author)2013-06-23

FYI: eBay links expire after a short while. Posting a model number along with the links would make this instructable much more useful a few months or years from now. :)

For those who have access to military surplus stores, you can get these cans MUCH cheaper. This size costs me $4 or $5 (if it's not on sale) at Smith & Edwards near-ish Hill Air Force Base in Utah. There is a smaller size as well that I love, except that it can't hold very large batteries. And I have done one with four 6" drivers (two of them coaxial) in a roughly 18"x18" (0.5m) can with two massive batteries. I gave it to my brother for his birthday to use at his shop. It is loud enough with an 18w Lepai amp (<$20 on eBay) to "enjoy" it from all of the neighboring shops. :)

I didn't read all the way through this since I know how to make them (just wanted to see your pics), so maybe you covered this, but just in case I would advise anyone who tries this to make ample use of threadlocker such as Loctite 242 and hot glue to keep things from rattling. Speaker gasketing (looks like weatherstripping but WAY better) is also well worth the small investment. :)

WillERoberts (author)jonkun2272013-06-23

Thank you for the feedback! I will try to post model numbers if i can find them.

Unfortunately here in britain ammo boxes are very hard to come by and when you do find them in surplus shops they tend to be over priced.

I have considered glueing but i have not experienced any rattling so i decided not to bother. Thanks again :)

jonkun227 (author)WillERoberts2013-06-23

I certainly didn't expect you to have a US Army/Navy Surplus nearby. I was mostly just putting the info out there for others who want to try it.

I wish there were substantially smaller ammo cans. The smallet size is only smaller in depth, not height or width. I want to make very portable ones with this same design aesthetic and lithium batteries powering a PM8403 amp (going by memory here; they are about $2-3 each on eBay and incredibly small. That and a set of Gento 2" full range drivers would be really cool.

Oh, the other addition I want to try with these full size 12v units is a solar panel and charge controller (each under $20 on eBay) so I never have to plug it in. I have ruined many SLA batteries by letting them sit without a charge. is a great resource here.

Keep this attitude of sharing what you learn throughout your career and you'll do well. :)

WillERoberts (author)jonkun2272013-06-24

You don't want to use anything much smaller than a .30 cal. ammo box because you need space in the box for the sound.
If you are looking for a small box, have a look for small Nato grenade boxes. (

If you do try solar i would recommend using a voltage controller otherwise you could fry your amp.
Thank you for your comments :)

nvarga (author)2013-06-23

Hey this is a great project nice job! I was just curious, instead of having a battery pack and replacing batteries all the time, I thought it would be cool to integrate a solar panel on top and have a small "power wheels" sized battery inside the box getting rejuiced and storing the power. I want to try this next.

WillERoberts (author)nvarga2013-06-24

I have thought about it but i haven't done it due to cost. You would need to have a voltage regulator attached to your solar panel which adds more bulk (and cost). If you do it, post some pictures here!

vultureman96 (author)2013-06-23

Does anybody reckon they would be able to modify this to hook it up to a 240V AC power supply?

That is what my panel mount DC port is for. I've got a wall plug which puts out 12v DC. You can buy them for around £8 online.

About This Instructable




Bio: Student studying physics, geology, maths and design technology:graphics products.
Add instructable to: