Introduction: Ammo Box Speakers

About: Student studying physics, geology, maths and design technology:graphics products.

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

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

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

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

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

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!

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

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.

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