Ammunition Can Speaker


Ammo Can Speaker front  Ammo Can Speaker Back

I was looking for an electronics project I could build after teaching myself to solder (by building a lot of Velleman 3D Christmas trees) when I came across Ross Hershberger’s Monobox amplifier project.  Right away, I knew I had to build this.  I tried to find a cigar box that would work, but didn’t have much luck.  But then I remembered that I had some old ammunition cans laying around, and inspiration struck.   It was a fun project that came out great, and I continue to enjoy it as it makes a great companion for my iPod.

This project was featured on the Make Blog: MonoBox Mods: Same Circuit, Two Builds.  Read on to learn what parts I used, some of the difficulties I ran into, and to see a video of the finished ammo can amp.

The parts

Building and testing the circuit

Completed Circuit

The circuit is fairly simple and easy to build, but I did run into a problem.  In a couple places, it’s necessary to insert two wires/leads into one hole on the PCB.  The vintage caps I used have pretty thick leads, so inserting the .010µF and .022µf capacitors together that make capacitor C1 was not possible without modification.  It’s a cheap trick, and certainly not a "best practice", but I ground down the leads using a Dremel to make them fit.  I had to do the same thing in another spot where a lead and a jumper are inserted into the same hole.

With everything assembled, I fired it up and was pleasantly surprised to find that the circuit worked on my first attempt using a small 3" speaker.  Success!

Building the enclosure and mounting the components

Cutting the ammo can  Circuit board mounted inside

The ammo can needed a 5.25" hole cut out for the speaker and several other holes drilled for mounting bolts and the power and signal jacks.  The hole for the speaker was the most work, but it came out okay.  I took my time, running two passes with a Dremel and a cutting wheel (actually, 4 cutting wheels, they wear out fast on the thick metal.)  After cutting, I cleaned up the edge with the Dremel using a grinding wheel followed by a sandpaper wheel.  It’s not perfect, but it came out much better than I expected.

The circuit board is mounted at the bottom of the can upside-down using some 1" nylon washers to hold it up.  A nice thing about the ammo can is that there is a large indentation in the bottom to make the cans stackable (so the handles have room.)  This is nice because there’s enough room so that any screws installed in that area are sunk in enough to prevent them from interfering with the can sitting level on a table or other flat surface.

Speaker mounted  Battery holder

The speaker is mounted with the cork gasket and some nylon washers to ensure it’s secure.  I also mounted a toggle switch which allows for selecting between the external power and an internally mounted 9v battery.  The switch is mounted inside to prevent it from being damaged as the ammo can amp is hauled around.

Rattle, rattle, rattle

Polyfill added

With everything in place, I stuffed the box with Polyfill, closed it up and it was ready to go!  Or so I thought.  I found out quickly that it had quite a rattle when the bass hit.  This was occurring in two places – between the lid overhand and the bottom portion of the can, and between the lid and top carrying handle.  To stop the rattle, I cut up some scrap sweeper belts which are about .06" to .07" thick.  i bent the lid a bit to make room for them to fit.  They’re glued in place with E-6000.  If you try this, keep in mind that belts are generally smooth on both the ID and OD – they need to have the surface roughed up a bit to get them to adhere to the glue.  I didn't have to do this since I had obtained some ground belts from work.


I’m real happy with the finished ammo can amp.  It has a vintage feel to it which I like, due to the slightly rough condition of the ammo can and the retro-looking speaker cloth (Parts Express #261-810).  The sound is good, not great; but it’s better than I had expected and there is a possible solution to making it better which I get into below.  The main goal of this was to create a fun, portable speaker with lots of DIY charm.  In that regard, it exceeds expectations.

Possible modifications/enhancements

There’s a few things I’d like to try to make this project better.

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Originally posted June 2, 2013 on my old site; posted here 3/28/2018 with a few revisions.