Introduction: Portable 3-way Hifi Speaker/boomcase

Welcome to my first instructable!

In this instructable I will just show you how I built my speaker and hopefully this will give you some kind of ideas how to make your own.

I wanted to build a portable hifi speaker/boombox that I could take with me anywhere. I looked at boomcases on the internet which gave me ideas of how I could build mine.

Here is a short video of the finished speaker:

Step 1: Materials

Here is a list of the materials that I used:
-1.2 cm thick plywood
-White artificial leather
-Black pvc angles
-Rubber feet
-contact adhesive
-wood glue
-corner protectors

Car amplifier from dealextreme. 2x20W (I recommend another one something like lepai for instance)
-10" bass speaker (80W rms max)
-5" mid speaker (70W rms)
-tweeter (10W rms)
-mc battery
-battery charger
-panel voltmeter
-panel ac input
-audio input
-on/off button
(-resistors to dampen the tweeter)

And then I added a LED strip underneath the speaker and for that I needed:
-soldering iron
-heat shrinking tube
-50 cm LED strip (ebay)
-sound sensitive LED controller (ebay)

I did not have all of this at home when I started the project. But when I knew how I wanted the speaker to become I started buying parts.

Step 2: Building the Box - Cutting the Plywood

The recommended minimum volume for the bass speaker that I bought was 40 litres. SO I made some calculations and decided to have these measurements on the box (outer size):  52,5x42,5x22,5 cm 
This would give me about 45 litres, a few litres extra for battery, amplifier etc.

I asked my dad to help me cutting the plywood, because I'm not very familiar with a circular saw.

Step 3: Building the Box - Putting It Together

All the pieces was glued and screwed to a 2x2 cm wood which I have in all of the edges.
I did not screw the plywoods onto each other because that would risk the plywood to crack or break.

As you can see the front has a hole for the amplifier. I just sawed it out and grinded until it fit the amplifier.

Step 4: Building the Box - Cutting Holes for the Speakers and Electronics

Now it's time to make the holes for the speakers. I made some planning and drew some circles on the speaker box, and after a few changes I cut the holes with a jigsaw. The hole for the tweeter was a little bit tricky because the jigsaw couldn't turn that much so I had to saw back and forth a few times instead.

Then I checked if the speakers fit the holes and they did not so I had to make some grinding to enlarge the holes.

To make the speaker box extra steady I attached a piece of plywood in the middle, where the handle would be attached later.

Finally I sanded the whole box so nothing of the plywood edges would be visible later.

Step 5: Covering the Box

I found that it was easiest to use wood glue to glue the artificial leather to the box. So I just spread the glue with a plastic card on one of the sides and put the artificial leather on it and attached it with staples. Then I cut the excess and the holes with scissors carefully to not cut anything that would be visible later. 

As you can see I attached the leather from the amplifier hole inside the box to hide the staples because the amplifier was not really made for panel mounting.

Step 6: Screw Everything in Place

Now we need to put everything in place and I started with the amplifier. It was very tight but I wanted it to be screwed to the box so I attached a piece of wood inside the box (see picture) with screws, I did this before I glued on the artificial leather.

The speakers were attached with 4 screws each. Later on I thought the color of screws were a bit ugly so I spray painted them black.

A button and a voltmeter was placed in the holes that I made. I just cut a "X" in the leather, put some glue under the leather and pressed down the voltmeter, button and an ac input which is not shown in the picture. So I only glued the leather to the box and not the components so I could remove them later if needed.

Step 7: Electronics Etc.

After a lot of thinking I decided to buy a 12 Ah battery which is A LOT for a speaker like this. It should last about 20 hours (measured with ammeter on medium soundlevel), maybe overkill but I wanted it to last long.

I soldered the speaker cables to the crossover and attached the crossover to the output of the amplifier. I powered it up and tested the sound but I thought the tweeter was way too loud so I bought some powerful 10W resistor which I soldered to the tweeter cable.
The amplifier was connected to the battery and the battery charger was connected to the ac input and to the battery. 
Voltmeter was connected to the battery and the button as well.

I used screws and zip ties to fasten the 4.5 kg battery.

As I wrote in the beginning of this instructable I wanted to have LED lighting underneath the speaker. So I bored a hole in the box and put the LED controller wires through and soldered them back.

Step 8: Testing Before Finishing

This step was very important because when I close my speaker box I can't open it again, not easily. So I used the speaker for about a week with the backside, but without attaching it. Just to make sure that everything was working as it should. 

Last pic:
Then my plan was to cover the edges of the artificial leather with some kind of plastic angle. I wondered what color would look the best, so to see how it would look with black edges I took some black paper and made some fake angles for my speaker. This was a really good idea because now I could see how it really would look with black angles.

I thought it looked very nice and cool so I went for the black angles.

Step 9: Closing the Speaker

I had some old speakers lying around so I took some glass wool from them and glued it to the walls of my speaker. I think this will dampen the speaker box and improve the sound of the speaker. 

Finally, after a lot of waiting I could close the speaker and screw the back of it in place. I did not glue the back side of the speaker, so I would be able to remove it later if I needed to.

Artificial leather was attached to the this side exactly the same way as the other sides.

Step 10: Finishing the Look

I bought 6 metres of 1,5x1,5 cm pvc angles and attached it to all edges of the speaker with contact adhesive. To make the ends of the angles about 45° I used scissors and simply just cut it.

To cover the corners where the angles ended I bought metal corner protectors which I sanded and spray painted black.

Before I screwed the corner protectors in place I had to sand the angles because they were sticking out a little bit and the protectors couldn't sit very nicely until I sanded them.

Step 11: Enjoy the Speaker

This is the best part of the whole project, having the finished project in front of you and be proud of yourself!
I am really happy with this speaker that I built. It has a very good sound quality which was a bit a surprise because this is my first speaker I have ever built.

It is a bit too heavy to carry around (14 kg), but it is perfect as a portable hifi speaker at home or at a small party outdoors.

I hope I have given you some ideas and inspiration to make your own speaker. Please rate and feel free to comment if you have any questions or thoughts!
Good luck and have fun!