11 May 2017

Boomcase: the third version

The newest version of my DIY mashup between a boombox and a suitcase: the boomcase.

By In Gear, Make 6 min read

My first Boomcase – a vintage suitcase modified into a portable sound-system with serious battery, amplifier and speakers – was one big experiment. I kept modifying it, replacing parts, trying out new techniques, and as time went on the suitcase started deteriorating heavily. Reliability became an issue, and as time went on it was a gamble every time I took it on a trip if it would actually work. When it died just before a trip to Paris I gave up and decided to rebuild the entire thing. The result is pretty fine, if I do say so myself.


This new version is a lot cleaner than the previous two. The vintage leather suitcases look nice, but have a severe disadvantage: they have no internal structure. Because they’re just a soft shell, you have to build your own wooden frame to hold all the heavy parts, making the boomcase twice as heavy as necessary. It also doesn’t help that I’m a total noob when it comes to woodworking, which meant the frame in my first boomcase had terrible fit and finish.

While working on my second version I discovered vintage suitcases made out of cardboard and wood, which are sturdy enough to function as the structure for the speakers and other parts. I tried finding a suitcase like it in the thrift stores in my area, but they were all cleaned out – I was definitely not the only hipster turning them into sound-systems. And then I found this cheap, new suitcase at a local department store.


Okay, that world map design is pretty ugly. It’s not properly vintage, and only meant as a decorative prop. But for 2 tenners you have an actual structured suitcase with the right dimensions. Worth a try!

For this new version I wanted to try a new placement of parts, inspired by some builds on Instructables. Instead of mounting the amplifier controls on the front of the case, I wanted to mount them to the side so the speakers themselves would be the most prominent feature of the boomcase. It also looks a lot more professional:


After 3 hours of measuring and cutting I had the proper holes in the case, ready to transfer parts from my old boomcase to this new one. This decorative cardboard suitcase is definitely not as solidly built as a proper wooden one, but I was still fairly sure that it would be able to hold all the parts.


The interior of the case is lined with fabric, which I had originally intended to retain. But the first time I used a drill on the case to make starter holes for my saw, the fabric snagged on the drill tip and all the fabric was torn out in a single fell swoop. That could have gone badly, I realized at that moment, but at least no one was hurt. I definitely recommend removing any fabric lining before you try to do the same.


Technology-wise this version is identical to the last iteration of my first boomcase. A 7200mAh 12V battery from a scooter, an accusafe circuit with charger, a Lepai LP-2020A+ digital amp, and two Pioneer carspeakers. I haven’t done the calculations, but considering the experiences of other people with similar builds this should net me more than 20 hours of normal listening and a good 10 hours of party-level sound. And charging the boomcase is no problem either, the accusafe circuit is similar to the charging circuit in a modern smartphone and automatically makes sure the dumb battery can’t be damaged by over- or undercharging.


Another 3 hours later and all the parts were built-in. Compared to the days of work I needed to build version 1, getting it down to 6 hours is actually quite fast. It wouldn’t be profitable to build these as a side hustle, but I could see myself building a few more iterations of these as a hobby.


One entirely new feature in version 3 is this USB connector with weather-resistant cap. It has 2 5V USB connectors for charging phones while at a festival. The plug is actually intended for building into motorcycles, but it works perfectly in this scenario too. Very handy for taking the case to Lowlands or any other festival.


So what is left to do? I am rather worried about the boomcase’s handle. It is, after all, a decorative prop and not designed to actually be used to hold many kilograms of battery and speakers. Strengthening the handle is definitely on the future to-do list. I also can’t see how much charge is left in the battery – if the charge becomes too low, the accusafe will simply turn off the boomcase entirely. To make sure that doesn’t happen in the middle of a party I could install a voltmeter and check that periodically, as the voltage goes down along with the charge of the battery. That way I can make sure the battery isn’t too low – if the voltmeter shows 11.5V the battery is almost empty.


Another feature I’d love to have is bluetooth. My first attempt at installing a BT board into the first boomcase was a horrible failure though – they just aren’t good enough yet. A range of 1 meter is not enough, and if holding your phone is enough interference to drop the connection it’s rather hard to control the music. But it’s going to be interesting to keep an eye on developments in this area and see if new BT boards have better antennas.

And one last thing… the suitcase I used is just too new. They made it look a bit aged straight from the factory, but that’s not the same. It’s not properly vintage, it doesn’t have the right look. I’m interested in applying the techniques from Mythbuster’s Adam, who demonstrates these weathering tricks that he uses to make new props look realistically old.

Still have lots to do, as you can see! And what am I going to do with the empty shell of version 1? Well, maybe I can still get one last project out of that one…

(Original post in Dutch)

What do you think?