3 May 2017

Boomcase: version two

A lightweight and more portable version of my boombox x suitcase mash-ups!

By In Gear, Make 7 min read

For a friend’s birthday I decided to make something really cool: a light version of a boomcase, my boombox x suitcase mashup. It’s a bit unnecessary now that we have bluetooth speakers, but these things still pack a lot more punch and have a lot more battery power. My friend started a creative training agency that offers teambuilding courses based on theatre techniques. She’d seen my personal boomcase before and loved it – and I thought this might be a great gift to celebrate her new company. A stylish sound system that had more power than a bluetooth speaker, but didn’t look as ugly as a portable PA system, that she could just carry to clients? I thought it’d be pretty cool. And I’m pretty stoked about the result!


Let’s start at the end! This is what the boomcase ended up looking like. A vintage suitcase with a single, centered 2-way speaker on the front. A 3.5mm input next to the handle gives you an input to connect your phone or other audio device to play audio from.


Not too shabby. Or actually, it looks really shabby, which means it perfectly hits that vintage look I was going for.


I originally found this vintage suitcase at a local thrift store, an old case covered with canvas and leather trim over wood, and a stencil of the Dutch word for ‘dance’ on the front. Light, because it was made of a thin wood frame, but still solid enough to hold a speaker assembly. I’m not sure why the case commands you to dance, was the original owner a dance student and did he bring his shoes in this? We’ll never know, but I thought it fit the idea of a creative training agency perfectly.


The patina on the canvas and leather is amazing. The weathered character of the leather with subtle spots and scratches is something you really can’t get on a new suitcase without it looking fake – unless you’re an expert propmaster. Obviously, I’m not.


The handle might be the best bit of this case’s trim. A piece of leather stitched around a cork base, the leather having taken on a perfect deep cognac color thanks to the decades of being carried by human hands. The original label – this is ‘original bagages’ from Giovanni – is a fun detail to include.


Nog all rivets survived all this time, some had broken off throughout the years. I don’t have the tools required to shoot new rivets into the case, so I opted for simple nut-and-bolt solutions for all the places where this was necessary. They’re not particularly remarkable when looking at the case as a whole, and I think DIY repairs add more character to an object that I wantt to look this old.


Technically, this is the simplest boomcase I’ve ever made. Considering the rat’s nest of cables that sits inside my other cases, this one is nice and clear.


Really, the case just contains a digital amplifier, a speaker, a battery, a 3.5mm audio input and a charging port. That’s it.


Let’s start with the battery. My own boomcase runs on a scooter battery, which gives it a lot of power and capacity, but also makes it heavy. It doesn’t just require the battery itself, but also special charging circuits and chargers to operate safely. I didn’t think that would work in this gift, so I opted for a lithium-ion battery from China instead. The advantage is that they’re very affordable and bang-for-buck, with built-in charging circuits and simple external chargers similar to what you’d use to charge your phone. The disadvantage is that these Chinese batteries work, as long as they work. There is absolutely no guarantee that they’ll work for long, and the promised capacity is heavily exaggerated by the Chinese producers. But for a boomcase that tries to be as light as possible, it’s still the perfect choice.


Extending the charging port to the exterior also makes it much simpler to use the case, as charging cables don’t have to be hooked up to the battery directly. This was you only have to connect an external charger to the case.


To turn all that power into actual music, we also need an amplifier. A very popular option for these kinds of builds is the Chinese TA2024 amp. This simple and light Class D amplifier needs very little power to create an impressive amount of sound. A disadvantage of the TA2024 is that it wasn’t designed to work with weak sources like phones and MP3 players straight out of the box, requiring some modifications to work best.


After the amplifier comes the speakers. My choice for this build was a Pioneer car speaker. Car speakers are combined speakers – they have both a woofer for the mid and bass tones, and an additional tweeter for treble, combined in one single unit. Normal speakers would require you to install the woofer and tweeter speakers separately, but this makes the install simpler and more compact. By deciding to use just one speaker, we also halved the amount of weight required for the case. It’s not a huge case so it wouldn’t be able to deliver quality stereo sound anyway.


If you do have two speakers you can run a stereo signal, but with just one speaker you need a mono signal. You could just pick the left or right channel to play, but the proper way to do this is by using a summing circuit. This combined the sound on both the left and right channels into a single mono signal. You can easily do this with a few resistors to create a stereo-mono summer. I found this circuit online, soldered it onto a 3.5mm connector and hid it in some heat-shrink tubing.


The 3.5mm mini-jack connector goes to the exterior of the case too. Any device that can connect a simple headphone cable can be used as an audio source this way, without having to open up the case to connect cables to the amplifier.


I used the speaker cover as a guide to draw an appropriately sized circle on the lid. A jigsaw then made easy work of cutting out the circle for speaker from the suitcase. I was kind of worried about this bit, as it did not go smoothly in previous builds. But the thin, wood material of the case was very easy to work with and the dimensions were perfect because I used the cover as a guide.


The cover started out with the standard glossy plastic look. I thought this did not properly match the rest of the vintage vibes of the suitcase, so I sprayed it white. Better, but pure white still didn’t match the weathered look I was going for. I used some sandpaper to rough up the paint, especially on edges that would have worn away over time, and then used a few spritz of black spray-paint and some drops of cold coffee (!!!) to add a more used, aged look to it.


To really finish off the speaker cover I wanted to integrate the logo of her agency. The cover originally had a Pioneer logo on the front, which would make an ideal spot for her logo. I used water-decal paper to transfer the logo from printer to the cover – which went horrible, as decal placement is a whole skill on its own. After about 12 attempts I finally had a logo on the cover that looked decent! A few layers of transparant lacquer later and the logo is now a permanent, perfectly applied part of the case.


And that’s my second finished boomcase! As you can see, it’s not that hard to create one of these boombox x suitcase mash-ups at all, especially if you don’t try to use more advanced parts than is necessary. Would love to see any boomcases you guys build!

(Original post in Dutch)

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