Introduction: Speakers Bros.

About: I'm only a guy who likes to make things.


Two versions was made: one that uses a pair of 3" full range speakers and two 2" passive bass, to gift a friend of mine, and the other one for my wife, who wants a portable speaker to enjoy her favorite songs, which is compound of 2 x 3,5" JBL woofer, a pair of tweeters and crossovers. All models use a 20Wx20W D class amplifier and a Bluetooth/FM receiver/pen drive reader. The box was made of MDF laser-cut parts covered with a natural wooden sheet. This kind of mount makes the speaker box lighter and improves sound quality. One of the devices uses an internal 12V @ 3A power supply and has an awesome sound. The other one uses an external 12V @ 3A power supply, since the frequency divisors (crossovers) take up a lot of space in the box. Now I'm pleased to share the assembly process and hope you enjoy it like I did!


Version 1

* Laser-cut MDF and acrylic parts

* 20x20W class D amplifier

* Bluetooth/FM receiver/pen drive reader module

* 3" speaker

* 2" passive bass

* Wooden sheet

* 12V @ 3A switched power supply

* 19mm diameter stainless steel switch

* Cables, connectors, nuts and bolts

Version 2

* Laser-cut MDF and acrylic parts

* 20x20W class D amplifier

* Bluetooth/FM receiver/pen drive reader module

* 3.5" JBL speaker

* 2" tweeter

* Homemade crossover

* Wooden sheet

* External 12V @ 3A switched power supply

* Cables, switches, connectors, nuts and bolts

Step 1: Electronics

As I said, I used a small 20Wx20W class D amplifier and a Bluetooth/FM receiver/pen-drive module for this project. A coaxial cable was required to connect the module to the amplifier as there was too much background noise using common wires. To prevent the module overheating, I used a heat sink on the integrated circuit. The entire system is powered by a 12V @ 3A switched power supply, which is plugged into the back cover of one device. The other version uses an external power supply. I have made a tiny PCB to distribute the power to the electronics components. The frequency divisors (crossovers) was drawn to work with a woofer, for the mid and low ranges, and a tweeter, for the high frequencies. I fixed the 8.000 Hz as cut frequency to define the coil and capacitor values. Then I drew and made the PCB's, enroll the coil and set up the circuit. The crossover is easy to calculate and the formulas could be easily found in the Internet.

One thing I must say is that I changed the front of the Bluetooth module to another designed by me in acrylic covered by black film.

Step 2: The Box

The design is clean and simple. The purpose of this project is to build an equipment that could be light, portable, with a good sound quality. The idea was also offer more than one way to listen to the music, as by Bluetooth, pen-drive or even FM radio broadcast.
I drew the project in CAD software, whose parts was laser cut in MDF and acrylic plastic. To attach the speakers and the back cover I used wood tee nuts. It was glued, painted, wooden sheet covered and vernished, as shown in the pictures. In fact, the assembly was easy and it is not difficult to do so.

Step 3: Final Assembly

Finished the box, all the elements was put on together. Placing the electronics, mounting the speakers and connecting the wires was not so hard. In fact, as seen in the pictures, the final assembly was easy and enjoyable, with all the components fitting together with no difficult. It takes only a few minutes to do the job, and the equipament was ready to be used.

Step 4: Conclusion

The sound of both models is good, but the one with frequency dividers is better, as the frequency ranges have been split to be played by the appropriate speakers, ensuring improved equipment performance.

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