Finding a use for old electronics can feel a bit pointless at times, especially if it was free swag and you never wanted it in the first place. Luckily for the old electronics in my life, specifically old portable speakers, there is a light at the end of the tunnel.
In this Backpack Speaker Hack Instructable, I'm taking apart some old portable speakers, designing new housing and incorporating them into a backpack. I've made sure to touch on some key design elements that guided me through this build.
Step 1: Step 1: Supplies
- - Portable speakers (Ideally the ones you can charge with a USB or power with batteries)
- - A backpack
- - CAD Software (I'm using Fushion 360)
- - 3D Printer
- - Precision Driver and Bit Set
- - Calipers
- - Scissor, X Acto knife or Laser cutter
Step 2: Step 2: Harvesting You Parts
"Cheap" plastic speakers are typically held together with fasteners, usually some sort of screw. First, look at the speaker you've chosen and try to locate where the screws are. Depending on who designed the speakers, the screws will be visible and or hidden under a feature. Once the main screws are removed, dissemble the housing and access the hardware. There are several components you need to keep:
- Screws (can be reused)
If the PCB is attached to something, and can't be easily removed, just leave it on. This can become part of your new speaker case.
POINTER - Try to avoid as much physical contact with the PCB as possible. If you are statically charged, you run the risk of frying your circuit board when touching it.
Step 3: Step 3: Measuring Your Speaker Parts
Using calipers, measure the speaker parts you harvested. The measurements collected will help inform you on how to design the new speaker case.
Areas that are important to measure
- The Diameters of the speaker components (cone, gasket, basket) *
- Combined height of speaker and PCB (Helps determine the height of the new case)
- Dimensions of the PCB (Helps determine the shape of the new case)
- Location of screw holes (Using existing features makes design a lot simpler)
*Search up "parts of a speaker" to get an idea of speaker components
Step 4: Step 4: Designing the New Speaker Case
Designing a speaker case in CAD can be an easy process if you set the right parameters. Here is a quick list of parameters you can use when starting to design:
- Dimensions of existing components (Like the ones in Step 3)
- Assembly methodology (Friction fit, glue, screws)
- Form factor (Do you want it to look interesting)
- Accessibility of important features (USB connection, headphone jack, etc)
When designing the speaker case for this project, I took into consideration all of these factors. Most importantly were the dimensions gathered from the speaker and PCB + housing. These measurements governed me during the designing of the new speaker case. I used the PCB fastener holes, as well as its outside diameter, and the location of the power port in determining the size and structure of the new form.
To insure the speakers fit securely in the housing, I used the basket measurements to determine the diameter for the speaker mounting hole. I wanted everything to be press fit together and secured with screws.
The speaker screen, which protects the diaphragm and suspension of the speaker, is a simple component to make. It has the same diameter as the new speaker case, with simple staggered slits for sound to escape from. It attaches with four screws. The key to the screen design is to insure that it doesn't damper the speaker diaphragm. Basically, just make sure the screen's not touching the speaker.
Once you have a completed model, you're ready for 3d printing.
I've attached an IGES. file to show the 3D model I made in Fushion 360.
Step 5: Step 5: Assembling the Speaker Case
To assemble the speaker case, I simply press fit the speaker into the new casing to secure it in place. The PCB and its original housing are then press fit into the new casing and secured with screws. I had fairly tight tolerance +/- 0.010" to make sure that the speaker was secure and the PCB was tight against the new speaker case.
Step 6: Step 6: Laying Out Speaker Location
Not all back packs are the same...obviously. That being said, there are some key things to consider when laying out the speaker locations:
- Direction of sound
- Keep the speakers from being obstructive inside the bag
- Avoiding cutting seams
- Symmetric and balanced (Use seams as guides, and bag components for center lines)
I chose to put the speakers on the side of the backpack because they projected sound better from there, and they didn't take up as much room in the bags interior.
Step 7: Step 7: Cutting the Backpack
Cutting the holes for the speaker case can be done with a pair of scissors, X Acto knife and or a laser cutter. Depending on the cutting methodology, a support structure may be useful. Cardboard is a quick and easy way to bulk up the backpack, flatten up the sides and provide support while cutting.
When Laser cutting, it is vital to have a support structure to flatten out the surface. Otherwise, you run the risk of the cut coming out deformed, which could ruin the backpack.
Step 8: Step 8: Final Assembly
With the speaker case fully assembled and the holes cut, its ready to put together. Fasten the screws into the speaker screen until the screw tips are slightly sticking out of the opposite side. Line up the screw tips with the holes on the outside of the backpack and press the fabric flat against the speaker screen. Adjust until you can see the screw tips poking though the backpack fabric, and appear in the interior of the bag. Then align the speaker case holes with the screw tips and tighten the screws.
QUICK TIP - If your backpack is constructed out of an outer shell fabric and liner (which is very possible), use rubber cement to adhere the layers together. It makes it a lot easier when navigating screws through small holes.
Step 9: Step 9: Plug in an Play
Plug in your music and enjoy! Nothings better than annoying the public with loud obnoxious music emanating from your back. But if that isn't your cup of tea, then perhaps viewing it as a pleasant sound track to your outing would be more appropriate.
Happy Making !