Portable Bluetooth Speakers (fin)

I finally invested in a $20 heat gun from Lowes. They're not only useful for bending acrylic sheet but also for desoldering SMD components:

http://www.instructables.com/id/Heatgun-Desoldering/?ALLSTEPS

You want to work on a surface that will not be damaged by heat. In this case I worked on some ceramic tiles and newspaper.

This was the outcome of the first bend (crack is from the failure last time).

Turn on the heat gun to full heat and run it up and down the line until the acrylics gets all floppy.

When it's malleable enough, you can bend it to the correct angle and hold until it sets.

Doing the second bend

All the bends are complete! we have a nice triangle.

I bought a huge sheet of faux leather for $10. I will be covering the frame in this so it looks sweg.

Mark out the surface area of the triangle. Leave extra room for folding.

This part isn't totally necessary, but it's good practice. You will want to line the inside of your speaker enclosure with some sort of dampening material so it doesn't vibrate and sound crappy.

I used some material from an air filter. Here I measured out how much I needed.

Cut holes for the speakers.

I secured the material in place with hot glue.

I didn't have a great method of securing the leather onto the surface. I used a combination of glue stick glue and hot glue to secure the leather in place.

Simply wrap the leather around the plastic casing.

The downside of using some sort of solid glue is that it leaves marks.

After you're done wrapping, cut out the holes that were there with a knife.

This  next part is an overview of the circuitry inside of the portable speakers.

I took apart a portable phone charger for the 5v power source. This power source was a bit small and couldn't provide sufficient power for max volume. You would want to take apart a battery back that has more than 1000mAh capacity.

I removed the USB socket from the board to save space.

Soldered wires to the aux female connector.

Soldering the aux plug to the PAM8403 amplifier.

Here, everything is connected.

• Speakers connected to respective "left" and "right" outputs of the PAM8403 amplifier
• TRS female connected to respective "left" and "right" inputs of the amplifier
• Power source connected to switch, connected to the amplifier.

We almost forgot to add bluetooth!

I bought a USB powered bluetooth module for ~$5. These are extremely useful if you want to add bluetooth audio to your car.

We just need to take this apart, connect it to the speaker power, and connect the audio output in parallel to the existing plug.

I asked a friend to cut out the endcaps for this project. The outcome was beautiful.

After all the electronics were finished, I shoved everything into the speaker box and glued in the end caps.

I have the recharging circuit board poking out so I can charge it 

Suggestions for the future:

• Use a 10,000mAH power source. with more power, your speakers will be louder, last longer, and have exceptional range for bluetooth
• perhaps have a circuit board in the future so the inside isn't a messy nest of wires.

That's it for now! Hope you guys enjoyed.

Portable Bluetooth Speakers

Back in 8th grade when I had a lot more time on my hands, I always wanted to build a decent pair of speakers.
I had built several speakers back then already: some were literally just speakers with an amplifier circuit, all exposed
some were speakers people threw out and I modified them
most of them were just ugly, delicate, and not presentable or usable in everyday conditions.

This folder of links has been on my Google Chrome browser for 4 years:

The links that I told myself I would look at eventually:

• http://ccs.exl.info/cust_cr.html - this link was useful for finding out what components I needed to build a real nice amplifier circuit
• http://www.diyaudioandvideo.com/Guide/BuildSpeakerBox/ - this page gives data for calculating what the dimensions of your speaker box should be based on what tones you want to resonate most. It also gives data on what material you should use for your speakers, and what find of damping structure you should put inside your speaker box.
• http://www.circuits.dk/calculator_multi_layer_aircore.htm - calculating the amount of turns you should have on an inductor coil for optimal bass response
• http://www.jlaudio.ca/header/Support/Tutorials/Enclosure+Bracing/Tutorial%3A+Enclosure+Bracing/624625 - this discusses the structure inside your speaker box so that air can move through it 
• http://www.instructables.com/id/DIY-Hi-Fi-WiBAQ-Speakers/#intro - general instructions on how to build speakers!

As you can see, building speakers is a very involved process. This is probably the reason why I did not go forth with this project back in 8th grade: the amount of things I needed to consider were daunting and I put it off.

• I would need to consider how much money I wanted to spend on what type of amplifier circuit: Class A? B? C? D? each class gives a different sound quality, but A is much more expensive than D, and much less power efficient. It's the difference between vacuum tube amplifiers, and a regular transistor based amplifier:
  
  vs
• I would need to consider the shape of my speaker and the structure inside. There are two ways to approach this: a ton of trial and error or a ton of math.
• I would need to consider what material I would build my box out of. Should I use the acrylic sheets I have lying around, or should I invest in MDF board for higher sound quality?

So I never took the time to consider all these things.

Yesterday I looked at the project again for the first time. I realized that sometimes you need to stop thinking and just do: otherwise you stay stuck. 

Here are the plans for the speaker:

• Triangular prism shape (like a Toblerone box)
• Build out of acrylic sheet, covered with faux leather
• Wooden end caps 
• two speakers in the front, two tweeter speakers on the side
• Class D amplifier (This time around I don't think I want to get involved with figuring out circuitry, so I'm going to use a prebuilt Class D amplifier, the PAM8403. It's low voltage, cheap, and relatively high quality)
• Bluetooth and auxiliary connectivity!
• 2600mAh rechargable battery

It might not be the highest quality or the most optimal design, but it's better to start something than to not do anything at all.

Here is the progress so far.

You need an 11" x 14.75" sheet of acrylic

Some random trash for dampening the inside of your speaker box (this is so that when the speaker shakes, the whole speaker box doesn't shake and cause distortion)

Speakers and tweeters

Switch, PAM8403, some nuts, LED + resistor (for power indication), 100uf capacitors for the high pass filter for tweeters

Cut the sheet to size

mark down where you need to bend it (for the equilateral triangle shape)

mark out where you need to cut the holes for the speakers

nice fit!

attempt to bend plexiglass

 This is where I stopped.
Along with needing to acquire a bluetooth module, a battery, leather, wood, and an audio jack, I also needed to buy a heat gun.
Usually when I bend small pieces of plexiglass I use a cigar torch lighter:

I don't have a nichrome wire heating element to bend a whole sheet this large...

For now this project is at a pause, but I will keep updated on the progress!