A few years ago, in 2017, I attended a rather large music festival.
Apart from the music and general camping experience, one thing particularly got stuck in my mind: Someone wearing a beer crate as a backpack.
While one could argue this not being an unusual sight at a music festival, the thing that impressed me as a maker were the inner working of said crate: No beer, but instead a bluetooth-enabled, battery-powered music blasting system. And, true to the spirit of DIY, the whole thing was close to falling apart – but literally and figuratively a huge blast.
Naturally, after returning home, I set out to create my own.
I already had a beer crate and a broken boombox (electronics were busted, but speakers still good). So the only missing components were a power source and a car stereo. As usual, Amazon provides everything on a budget of ~50€.
- Lead-Acid-Gel car battery (~20€) https://www.amazon.de/gp/product/B00JJVSYMC
- Battery charger (~15€) https://www.amazon.de/gp/product/B001CNZP6S
- Car “HiFi” stereo (~20€) https://www.amazon.de/DollaTek-Hallo-Fi-Stereo-Audio-AMP-Verst%C3%A4rker-Unterst%C3%BCtzung-Auto-Motorrad-Auto-CD/dp/B07DK5MQP3
Next, I drew a rough layout of the box in 3D – to align the components: beer crate (light blue), car stereo (yellow), battery (dark blue), charger (medium blue), control panel (green), speakers (pink and orange):
The first step was to knock out the floor of the beer crate and replace it with a piece of wood:
Next, I wired in the speakers and the car stereo, and added a small battery voltage indicator:
After adding the charger and power socket everything was screwed in place using steel brackets:
The final steps were staining the wood to give it a nice finish, spraying on a logo and closing the box:
Boy, it slaps hard. But I encountered several problems, and found several solutions to them:
- Problem: Balance between High and Low was really off. Solution: Adjust knobs on stereo.
- Problem: The thing rattled when the base was turned up. Solution: Stuff the whole box with foam.
- Problem: Power cuts out when stereo pulls too much power. Solution: Don’t turn up the volume to deafening levels or add another lead-acid battery (WIP).
- Problem: Cumbersome to carry around. Solution: Add shoulder strap salvaged from boombox.
- Problem: Neighbours complain. Solution: Invite them, too.