Introduction: Fanny Pack Boombox

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I love fanny packs. There, I said it!
When I was growing up in the 80's fanny packs (bum bags) were all the rage. Big kids used them, and they were common with some adults, too. It seemed like everyone I knew had one. Not deterred by fluorescent colours or loud designs, fanny packs were the height of utility.  Somewhere around the mid-90's the fanny pack was cast aside as the ultimate fashion faux pas.

Fanny packs still exist today, but are a mark to those that are more couture-conscious. Wikipedia offers:

Many observers consider the fanny pack a sure mark of an out-of-place tourist, evoking the traditional tourist stereotypes known around the world, or regard them as an item worn by unfashionable or older people

Tough crowd. Seems like the fanny pack is going to need some help to make a comeback.
By combining inexpensive speaker amps with a fanny pack we can make a fanny pack boombox! Portable and fashionable music wherever you go!

This project modifies existing electronics and doesn't involve any difficult wiring and only basic soldering. To make your own, here's what you need:
  • 2x portable speaker amps ($5/each)
  • Fanny pack (thrift store)
  • electronic project enclosure box ($2)
  • drill, soldering iron, scissors, black paint
Of course, you can always just buy one..but what fun is that?

Step 1: Disassemble

I found these small portable speaker amps at a hardware store for $5 each. These small speakers are perfect as they are charged through USB and are simple to modify.

The speaker amp enclosure is snapped together and can easily be opened by squeezing along the seams of the hemispheres, a small opening should appear. I leveraged the opening wider with a screwdiver and the enclosure popped open completely.
Inside there is a battery, the speaker, and a circuit board with the audio input/USB charge jack and the operation switch.

Since we want stereo sound*, we're going to need another speaker. Harvest another speaker of the same size from another speaker amp.

*not technically stereo

Step 2: Solder

I desoldered the speakers off both speaker amps, cleaned the leads, twisted them together, and soldered them to a common speaker amp circuit.

This speaker amp unit also has a small blue LED to let you know when it's on. With the speakers being moved the LED could have been obstructed. I decided to add long leads to the LED so I could place it on the faceplate with the speakers.

Step 3: Faceplate

The top of the project enclosure will be the faceplate of our fanny pack boombox. 

With a measuring ruler, I divided the top of the enclosure into two halves and found the centre of each half. A speaker was positioned in the centre of each half and the circumference was marked with a fine tip indelible marker. Next, the centre of each circle was marked and a measured array of dots were made within the perimeter with a marker.

With a 1/8" drill bit, each dot was drilled out. Consistency in your array pattern is nice, but not required. I made a few mistakes when drilling my speaker openings and it still looks alright. Go slow, and be patient. If you're planning on putting an LED in the faceplate now is the time to make that opening. 
You could easily make this with a lasercutter; I decided to keep it low-tech.

After drilling the openings were deburred and the entire faceplate was sanded. Sanding removes and edges created from drilling and makes the faceplate matte, which is easier to paint.

The faceplate was primed, then painted with 2 coats of matte black spray paint.

Step 4: Cut Opening in Fanny Pack

Before we glue the electronic components to the project enclosure, we'll need to make an outline of the case on the fanny pack.

The project enclosure was used as a template and it's outline was traced to the front face of the fanny pack with a ballpoint pen. Once I had the shape of the project enclosure transferred, I offset the trace by 3mm inside the trace, this mark can also be made with a ballpoint pen (I used a white pen). This offset will allow the fabric to be sandwiched between the top and bottom of the project enclosure, fixing it in place once the enclosure is reassembled.

The offset opening was then cut out with sharp scissors.

Step 5: Base Opening + Glue

Opening in bottom of project enclosure
An opening needs to be made in the bottom of the project enclosure to allow access to the the audio jack access and power switch. The circuit board for the speaker amp we chose has an curved shape we'll need to make the opening a little larger. Your circuit may differ, so only make the opening as large as needed.

Using a permanent marker, trace and outline on one of the long sides on the bottom half of the project enclose. Using a rotary tool, the opening was cut into the project enclosure.

Glue components
With all openings made, the components can now glue the components in place. 
The speakers and LED can be glued to the backside of the faceplate, and the audi jack and battery can be glued inside the bottom half of the enclosure. 

Step 6: Close Enclosure

The project enclosure can now be inserted through the cut opening of the fanny pack. Align the project enclosure with the cut opening, and lay the fanny pack offset along the edges of the project box. Place the top of the project box over the offset fabric and close the project box, sandwiching the fabric between the top and bottom of the project enclosure.

Screw the project enclosure shut, affixing it in place with the fanny pack. 
A small opening was made between the front compartment of the fanny pack to the main compartment, this will be the conduit for the audio input. 

Your fanny pack boombox is now complete, you're ready to bring the noise wherever you go!

Step 7: Bring the Party

With the music covered you can pack the rest of your fanny pack with all kinds of goodies for your party

I stopped by the grocery store and grabbed some cheese, crackers, granola bars, and a few small adult beverages. Perfect for my impromptu park party. This is shaping up to be a fun time, thanks fanny pack!

Crank up those tunes, and stay fashionable!

Have you made your own fannypack boombox? I want to see it!

Happy making :)

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