Have a pair of mini beer kegs and wondering what to do with them?
Why not turn them into a pair of speakers for your audio system!
If you are looking for a unique looking speaker or happen to have a pair of mini beer kegs, then you should consider building this mini-project. Here in Ontario Canada, the LCBO sell these Heineken 5L kegs. They are great for parties and are made from what appears to be a fairly heavy gauge metal (stainless steel?). At the time I was looking for a set of small speakers for my home bar and thought why not use these mini kegs as a speaker enclosure!
My design idea was to mount a small woofer on the bottom of the keg and have it raised above the surface with a combination of metal standoffs and rubber feet. The rubber feet would prevent vibration when sitting on a hard surface like a bar top or shelf.
What to put inside your mini Beer Keg speakers
Woofer for the low audio range
I started by making a paper template of the bottom of the mini keg to determine what size woofer would fit. Based on the diameter of my template and the fact that I needed room to mount the standoffs / rubber feet I decided on using a 4″ woofer. I had a look on Amazon to see what was available in that size of speaker. I found this woofer: https://www.amazon.ca/Goldwood-Sound-GW-204-8S-Replacement/dp/B0002ZPSPU/ This is a 70 Watt 8ohm replacement speaker, which I thought would be perfect for this application.
Tweeter for high end audio range
In addition to the woofer, a tweeter is needed for the higher range of sound frequencies. My idea was to get something small that could be mounted to the top of the keg. I decided that a pair of small piezo tweeters would be ideal, since this type of speaker doesn’t require a crossover and can handle audio power very well. Once again I looked to Amazon and found these: https://www.amazon.ca/TW-17-Micro-Tweeter-Single-Black/dp/B0007WQ7PS These tweeters can handle 200W and come with handy mounting hardware. Perfect for this application!
Raising the keg
In order to raise the keg off the surface it would be sitting on I decided to use metal standoffs that would screw to the bottom of the keg. I had previously purchased a kit of standoffs on Amazon that contained these:
The kit also contained the machine screws that would be needed to attach these standoffs to the bottom of the keg. At the end of this article I will have a “Bill of Materials” list in case you would like to use the same kit.
To keep the speakers from scratching the surface of what they are sitting on and to prevent unwanted noise from vibration, rubber feet will need to be screwed to the bottom of the standoff. Turning to Amazon again, I found these: https://www.amazon.ca/Uxcell-a15090400ux0475-Vibration-Isolator-Absorber/dp/B07LF1J7ZB
These will be screwed to the bottom of the standoff using the machine screws from the kit.
Dampening internal resonance inside the keg
Also needed to prevent noise and vibration is some sort of stuffing to be places inside the keg, behind the woofer. This will also help with the low frequency performance of the speaker. To do this I bought a polyester stuffing: https://www.amazon.ca/Polyester-Stuffing-polyetser-fibre-polyfil/dp/B07JNV628L
Get at least a 2lb bag. This stuff is inexpensive and you don’t want to run out mid project. Besides, you will probably find other uses for it as well.
Terminals to connect to your amplifer
The last thing needed are some kind of terminal that will connect to the wires coming from your amplifier. Because these kegs are circular, I decided to go with individual positive/negative terminals for these speakers. Here is what I used: https://www.amazon.ca/Oiyagai-Amplifier-Terminal-Connector-Binding/dp/B07D3MMBJH/
These came in a package of 20, but I will be using the remaining ones in future projects (such as power supplies, battery chargers, etc)
Construction of the mini Keg speakers
1.) Cut and drill all the needed openings into the kegs
Once I had all the parts needed I began building the speakers. Very first thing I did was to make a 2nd template of the bottom of the keg. Then I carefully measured the back of the woofer to determine the size of the opening I would need to make in the bottom of the keg, I marked the center of the template and drew a circle corresponding to the size of the hole I would have to make for the speaker to fit. I also marked the location of the mounting holes for speakers. I ended up with something that looked like this:
The dark grey section is what will be cut out and the smallest circles are where small holes will need to be drilled for “self tapping ” metal screws to go in that will hold the speaker in place. The larger circles are where holes for the standoff will be.
I glued the templates to the bottom of each keg with a glue stick. This kept the template in place as I drilled and cut the bottom of the keg.
With the template in place I was able to begin the process of cutting out the big hole for my woofer. I used my electric jig saw with a fine tooth metal cutting blade in it. But first you need to drill a hole near the inside edge of the dark circle that is big enough to fit your jig saw blade. Then you are ready to cut the opening.
Once the large opening is cut be careful of the sharp edge that is left. Take a file and smooth out the opening . Next, have a look inside your keg. Depending on the brand of keg you have there will be some stuff in there that was used to propel the beer from the keg. Carefully pull this stuff out and set it aside. At this point you should have an empty keg.
Next center punch the center location of the 4 mounting holes on the bottom of your keg. Using an electric drill with a 1/16″ drill bit, drill the 4 mounting holes. The metal is tough, and I found a cobalt drill bit works best for metal. However, if you have just normal black drill bits, they will work but will likely dull very quickly. With a larger bit, drill the 4 holes for mounting the standoffs.
Now its time to decide which side you want to be the front of your speaker and which to be the back. I just picked the side of the keg I thought looked best to be the front. On the back, about mid way I marked the location where the binding posts would go and drilled a pair of holes to fit the binding posts.
Next have a look at the top of your keg. Decide where and how you will mount the tweeter. Since the tweeters I chose came with mounting hardware it was very easy. The little plastic wedge that came with the tweeter would be glued in place to hold the tweeter. But first I drilled a small hole near the top of the spigot (where the beer came out of) that will be used for the wire to the tweeter. And that’t it! You are done cutting the openings. Now its time for wiring and assembly of your new speakers.
2.) Wiring your speaker components
Below is a wiring diagram to help show how everything is connected together. You can use any thin gauge wire you may have on hand. I recommend having either 2 different colors or some way of designating a “positive” and ” negative” connection. Speaker wire works well in this application, since it has different colour conductors. Notice that your speaker components will have a polarity mark on them. Most likely a red dot to indicate a positive connection. As shown in diagram below, make sure to keep your connections consistent with the polarity of your speaker connections and the binding posts.
I ran the wire for my tweeters first (from the top of the keg to the bottom opening) , leaving lots of slack. Next I wired to the 2 binding posts and ran the wire inside the keg and out the bottom opening.
Mount the binding posts on the back of the keg at this time. You won’t be able to do this later in the build.
With the binding posts and tweeter wires coming out the bottom, all that was left to do was connect the wires to the woofer.
3.) Assemble your speaker
Now that all the connections are securely soldered together you can begin to assemble your new speaker.
Stuff your keg:
First take some of your polyester stuffing and place it inside the keg loosely filling it up. Don’t put so much in that it gets all compressed. You’ll want it to remain fluffy in order to properly absorb the rear vibrations from the woofer.
Install the standoffs and feet:
Reach into the opening and insert the screw into the hole for your standoff and screw on your standoff. Repeat for the other 3. Install the feet with screws into the bottom of the standoff.
Mount the woofer:
You will be using self taping metal screws to mount the woofer. These type of screws will cut their own threads into the sheet metal of the keg. Carefully fit your woofer into the large opening you made in the bottom of the keg and screw your self taping screws into the holes you had pre-drilled. Some force will be needed to drive the self taping screws in. Don’t over tighten, just tighten enough to seal the woofer in place.
Mount the tweeter
Stand your speaker up on its feet and look at the top of your keg for a place to mount your tweeter. I mounted mine just on top of the spout. See the photo below:
That completes the speaker assembly! Check your work for continuity with a multi-meter. Connect to you audio system and enjoy.
Parts List (BoM) with Amazon links:
- 4″ woofer (need 2) : https://www.amazon.ca/Goldwood-Sound-GW-204-8S-Replacement/dp/B0002ZPSPU/
- Piezo tweeters (1 package): https://www.amazon.ca/TW-17-Micro-Tweeter-Single-Black/dp/B0007WQ7PS/
- Brass Spacer Standoff Screw Nut Assortment Kit: https://www.amazon.ca/Hilitchi-360pcs-Female-Standoff-Assortment/dp/B013ZWM1F6
- Rubber feet: https://www.amazon.ca/Uxcell-a15090400ux0475-Vibration-Isolator-Absorber/dp/B07LF1J7ZB
- Polyester stuffing (get 2lb or more): https://www.amazon.ca/Polyester-Stuffing-polyetser-fibre-polyfil/dp/B07JNV628L
- Binding post terminals: https://www.amazon.ca/Oiyagai-Amplifier-Terminal-Connector-Binding/dp/B07D3MMBJH/
I’ve always been making things. My favorite class in grade school was shop! In High School my elective was Industrial Arts. Afterwards I went on to study Electrical Engineering and when I graduated I started working in hardware development at a small company. Making and creating things is something I grew up doing!