Fab Boombox snaps together for under $100
By Paul Ridden
December 29, 2011
Music lovers wanting to listen to digital music files on the move are pretty much spoiled for choice these days, whether keeping things personal with players like the Cowon C2 I reviewed earlier in the month, or sharing with friends using something like the FoxL v2 wireless loudspeaker. If commercial designs don't really appeal, though, there is another route - you could always build your own. Matt Keeter's Fab Boombox is just such a device, designed and built for a final class project and featuring laser-cut, snap-together panels housing stereo speakers (said to be loud in a quiet room and quiet in a noisy room), a custom main control board with an MP3 decoder and a 9V battery power source. Digital music is fed into the player via an SD card slot, with the user controlling playback on a touch-sensitive interface.
Keeter told us that the Fab Boombox was designed using tools and techniques from MIT's "fab lab" community for his How to Make (Almost) Anything class. The panels for the wooden case were shaped using a Universal laser cutter which gives the edges that beautifully-contrasted coloring, although more traditional carpentry techniques could no doubt be used for those not fortunate enough to have access to such expensive machinery.
"The sophisticated geometry of the case isn't at all necessary," says Keeter. "My advisor suggested that I make something more interesting than a wooden box, so the case went from an afterthought to a major aspect of the project."
The device's printed circuit board was designed in EAGLE as a two-sided board and cut using a Modela mini-mill. Keeter says that he chose a 9V battery to power the audio player due to time constraints and the relative ease of regulating the 5V needed for the main controller and the 3.3V for MP3 decoding, SD communication, and the audio output/amplifiers. The battery can be replaced when drained by removing the player's top panel.
Designing and fabricating a regulation/charging system for something like a Li-ion battery pack would have required more time than was available, and would have been outside the main goals of the project. Such things are not outside the realms of possibility, though, for readers inspired to create their own versions of the Boombox using the instructions, make files and firmware (written in the Arduino language) freely available online.
"Readers who want to make their own should have experience with surface-mount soldering," advises the designer. "There are a lot of components, and debugging soldering errors could be obnoxious. I think that all of the necessary information is on the project site, but it's definitely in a beta state - expect some amount of hackery to get everything working."
Upping the system's volume can also be undertaken by changing the pair of resistors which control the gain on the audio amplifiers, although Keeter warns that giving the Boombox a lot more volume may require a higher-power voltage regulator.
Between the speakers, the unit's uppermost front panel has been made responsive to touch input from the user. Each of the five playback icons carved into the wood sits above a copper pad at the rear. These pads are wired into the input board, but the free-floating nature of the current design has led to some interactivity issues.
"The touch buttons work great when the thresholds are set correctly," explains Keeter. "Unfortunately, the analog pad wires float in the center of the box, because they are connected from the front panel to one of the PCBs in the middle. This means the correct thresholds vary depending on how the wires end up hanging. This is an easy fix - the capacitive input daughterboard should be mounted on the front/top so that the analog wires are fixed in place."
Keeter told us that now his studies have concluded, he intends to work on a more sophisticated version of the Fab Boombox, and has promised to keep Gizmag updated.
While you can get quite a lot for under US$100 these days in terms of consumer digital music players, this self-build project is attractive and functional enough to earn some shelf space in my office. What do you think?
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