200W Boombox (How to Build)

This step by step guide will show you how to make your own boombox. So go forth and gather your tools to create your own awesome sounding boombox.....




Tools you may need:

• Drill
• Variety of drill bits
• Table saw (or a normal wood saw)
• Hack saw
• Selection of screwdrivers
• Wood and metal files
• Chisels 

Basic Info:

There are four main components to a boombox that determine how it performs:

• The amplifier
• The speakers
• The power source
• The housing

The amplifier I used was an unbranded 200W rms amplifier which was perfect for the deep bass notes at high volume. It was also conservative of battery life.  I used two speakers from maplin (UK), which were 6 1/2 inchs, 75W peak, mid to bass drivers. The boombox is powered by a 9AH sealed lead acid battery that is charged internally with a trickle charger. I used 18mm medium density fibre or MDF to construct the housing but would recommend a thicker material for yours, however the diamension will need changing.

Parts that you may require:

• An amplifier in the range of 150W~300W RMS
• 2x 6 1/2" 75W hi-quality speakers 6 ohms
• a sealed lead acid battery of about 9AH but the higher the capacity the better
• several large off-cuts of 3/4" MDF
• sheet aluminum to make the interface panel
• various screws
• heavy duty flight case handle
• 3.5mm headphone to RCA cable
• textured stone effect paint
• mains junction blocks
• switches
• wire

The Box in boombox is made out of 6 pieces of MDF each (see first diagram):

• 2X panels of      18" X 12"
• 2X panels of      18" X  7"
• 2X panels of   10.5" X  7"

1. I used a circular saw to cut each piece accurately. If you ask the timber yard nicely, they may cut the wood to your dimensions for you. If not, just mark up the lines using a rule and a set square. Then cut them manually keeping the blade about 30° up at the back and along the line. Now sand down the edges however don't take them off completely.
2. Now get the worst looking big panel, this will be the back of the boombox. Use the second image to help when drilling screw holes for adjacent corner panel. Where B is the back and A is a side panel. Remember that the pilot hole for the screw must be smaller than the screw itself.
3. Attach the other side panels leaving the front panel for cutting the speaker holes in later.

Front Panel:
For my speakers I needed two 6" holes in the front panel. To do this, do this:

1. Get a compass and mark up the two holes.
2. Drill a hole large enough to put a jig saw blade in.
3. Follow inside the line with the jigsaw.
4. Sand back the excess.

It is best to paint the housing now, before adding any major components as not damage them.

What Paint ?
I used rust-oleum Black Granite textured spray paint as it gives a nice textured feel. I then added a coat of glossy black on top to give it some shine.

How to paint:

1. Make sure all dust, grease and wax is removed.
2. Assemble the boombox (ie all 6 panels)
3. Lay an old newspaper down and place the boombox on it
4. Using MDF primer coat the entire surface and allow to dry.
5. Apply the textured paint and allow the dry. 
6. Touch up any areas missed now.
7. Spray a fine layer of  high gloss black on top and allow to dry.
8. With some p180 grit paper very lightly scuff the tops of the bumps making them grey. This adds subtle but nice detail. 

It is now time to make space for each of the components in the box. BUT FIRST ....

Mount the huge speakers: 

1. Place the speakers in holes we cut out earlier
2. Find screws that fit in the holes
3. Drill pilot holes that are smaller than the screws for each speaker.
4. Screw the speakers in place.

Mount the other internal components:

As your components may be different there is no set layout to use. Try to arrange every component inside the box. This may take time but it should work out. For the battery I had to bend a piece of aluminum to make a bracket in order to keep it in the center of the box. This is important as an unbalanced boombox may seem heavier then it is. The other components where easier as the could be screwed down to the back panel. See the image to get an idea of component placement.

Fixtures and Fittings:
The handle you use will be different so you will have to follow the manufactures instructions. The control panel on the other hand will be very similar. The control panel will allow you to swithc between operational and charging mode, as well as controlling the internal aux power supply.

I took a IEC power connector from a computer PSU to use as my power inlet. I also used a grommet to protect the headphone cable and two switches, one a spst rocker and a DPDT rocker. See the third picture for the wiring diagram.

The PSU remain in standby untill the single switch is pressed. The charger stays on constantly as it draws very little power when disconnected. However it cannot be left connected to the battery when off, as this drains the battery hence the circuit above.

To make the panel:

1. Score a 5" by 5" square onto some plate aluminum.
2. Mark up the switch bore holes
3. Clamp the aluminum to some scrap wood and then clamp that to the bench.
4. Chain drill (multiple conjoining holes) around the inside of the markings.
5. File out the hole and repeat for the other switch.
6. Cut out the panel, file any bur of and rub it down with p180 grit paper.

To mount the panel:

1. Hole the panel to the housing and drill 4 corner holes
2. Screw down the panel
3. Drill and chisel the MDF out of the switch hole.
4. File back unit the switches can be pushed in.

All that is left is to wire up the panel and connect up the speakers.

Note about REM - with many thanks to karlpinturr for pointing this out:

Standard car amplifiers have a connection next to ground called REM, this is called remote and is used the switch the amplifier from standby to on. REM is normally triggered with 12V by the head unit (cd player) in a car. It is used to have a quick power up time however leaving the 12V of the amp permanently connected will drain your battery therefor I just power it up directly with the 12V input..

Just short the REM to the 12V input and turn the amplifier on by connecting and disconnecting the 12V input to the battery.

It is just down to the finishing touches now, but you should be fine with that. I forgot to mention I had also added some plastic feet to the bottom to protect the floor.

My Final Specs are:

• 160W RMS
• 14 hour battery life (when used lightly)
• 50lbs
• 2,000,000 dB                                                                                   (lie)

Check Out the Video:

Sorry for low volume it was early in the morning.