soundToggle by Bansal is a semi-portable bluetooth speaker. So named because of the toggle switch used to turn it on and inspiration from name brands, I made it because I recently heard about this tiny but powerful amplifier and had some old computer speakers laying around. Also, because you can never have too many speakers in your home.
The speaker is built around the PAM8403 class-D amplifier, paired with old but still good quality full-range drivers. The unique thing about these speakers is that they don't have distortion, even at high volumes, thanks to a passive 'pre-amplifier' I designed using some resistors.
The PAM8403 is a powerful amplifier. I added a piece of aluminium on the amp to act as a heat-sink, as continued use at high-volumes was making the board a little hot. I used some over-kill thick wires for the wiring in order to minimize any resistance and have the output as clean as possible.
The actual speakers I used were salvaged from a pair of old computer speakers. These are rubber coned full-range drivers which deliver exceptional sound quality and loudness for their size. I specifically designed the enclosure so that I get the optimum bass output.
The passive pre-amp I built which made use of resistors in a voltage divider configuration to essentially decrease the max-volume. It is something similar to having a volume control knob with the dial fixed. This also helps reduce hum/buzz that creeps in when the input wires are close to the power wires.
The Bluetooth module I used was a generic USB Bluetooth receiver, usually used in cars. I paired it with an LC-Filter to eliminate a ground loop as both the Bluetooth module and the amplifier had the same power source and omitting the LC-Filter would cause unpleasant noises along with the music, thereby decreasing the sound quality quite a bit.
After I had everything wired up and functioning, I moved on to experimenting with enclosure sizes and how volume was affecting the sound. I did this to get the maximum bass response out of the small enclosure possible. I also wanted to see how the enclosure can influence the acoustics.
After figuring out the correct enclosure size, I fabricated a box out of 10mm MDF board. I added a port in the front of the enclosure. To make the enclosure aesthetically appealing, I wrapped it with some carbon fiber vinyl. The Back Panel was painted and I added a grill in front along with some wood molding in the front to give the speaker a Classic-Retro look.
The speaker can be powered by any ordinary phone charger (Micro USB Type), by plugging it in on the side and flipping on the switch at the back.