Introduction: DIY Boombox / Ghettoblaster

Originally this project was started for a buddy of mine as a replacement for his pathetic iPod dock.

I was going to route out a slot to slide in / dock an iPad, but he ended up getting an iPhone 5 so the line out connector I bought would not work anymore. I then decided to go Bluetooth.

Tools used:

Table saw
Router
Circle Jig
Router trim bit
Measuring tape
Clamps
Soldering iron
File

Parts I used:

Tripath amp
BT-1 Bluetooth module
Parts Express Buyout speakers
(Both speakers I used are sold out, there are always good ones to choose from at PE though)
Stainless grab bar
Black counter top laminate from HD
1/2" plywood

(This is also my 1st Instructable, any tips or suggestions are welcome)

Step 1:

I first ran the driver through BBPro to get an idea of what size I needed to make it.

The enclosure typically  controls the response of the first couple hundred hertz. I looked at both vented and sealed designs.
While a ported enclosure tuned to 80 hz would give me 4-5dB between 80-100hz and had an advantage until it hit 45hz where they were even, after that the sealed box had the advantage and had 12dB more output at 20 hz than the vented design.

I went with the sealed design as my friend listens to a variety of music and thought that he would appreciate the extension over sheer output in the upper bass frequencies.

This is the response curve I ended up with

Step 2: Building the Enclosure

While building the enclosure I decided I wanted to make the box sturdy but light, I went with 1/2" plywood as a compromise between the two.

When cutting the wood I cut all the like measurements at the same time. Both pieces of the front baffle, the back and top and bottom were 23.5" so I cut all of those first.

From that I then cut the 3 - 11.75" tall pieces, then the 4.5" top and bottom pieces.

Leaving the fence at 4.5" I then ripped a piece for the 3 - 10.75" pieces that made up the sides and middle divider.

I laminated two pieces together for the front baffle so that I could recess the drivers to be flush with the surface of the boombox. I set the fence to 1/2" with a 1/2" cut depth and ran all the sides of the baffle through it to create a rabbet joint to increase the strength of the box. I also set the fence to 11.5" and ran it though on both sides to create a dado joint for the center divider. I chipped the wood out of these cuts with a flat screwdriver and a hammer as I don't have a chisel. I then ran some 60 grit sandpaper in these joints to clean them up.

I then used wood glue and clamps to put everything together. You could use screws, but I wanted to leave the surface as smooth as possible for the laminate to adhere to.

I then routed out the driver holes leaving the drivers 1/8" proud of the surface to account for the laminate I would be attaching later.

....If I were to do it again though, I would route the holes for the drivers after the laminate was attached and just put down some masking tape to protect the surface.

Step 3:

The tweeter I used was tested by Zaph and he recommended a 2.7uf cap for a crossover point of 3,300hz

I simply let the woofer run full range as it was a full / extended range driver anyway.

Speakers a wired in parallel and to the output of the Sure amp.

The Bluetooth module is powered off of a LM7805 voltage regulator and the headphone jack and power wires were removed and 20ga hookup wire was soldered on to run power between the BT1 and amp.

2 2200 16v caps were also soldered onto the wire in parallel with the power connections to help the low frequencies a bit.

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unfortunately this instructable was made after the fact and I don't have many construction pictures, so if you have any questions I will try to add the information at that time.

Comments

author
desertsniper made it!(author)2012-12-11

what was the total cost for this bad boy? also, how hard would it be to make it battery powered with rechargable batteries?

author
Cancerkazoo made it!(author)2012-12-11

I think i'm around $150-$180.
amp - $20
Bluetooth - $20
grab bar - $20
speakers $25 ish
laminate sheet $40
spray glue $10
plywood $16
Plus odds and ends and shipping here and there

I'm looking into making it portable and it looks like I can do 3s 2200ah LiPo($9) charger ($12) and a low voltage buzzer ($2) hooked up to a relay to cut power when any cell reaches 3.3v....plus shipping/tax

author
desertsniper made it!(author)2012-12-11

thats pretty awesome! cant wait till you post more, i would not mind building something like this.

author
Cancerkazoo made it!(author)2012-12-11

I'll update it as I have time. I need to pull it apart to add a power jack anyway. I'll take some pics of the boards and try do document the battery portion better. I haven't used sketch up in a while, but I can try to make construction pics that way.

author
desertsniper made it!(author)2012-12-12

sketch up is great!cant wwait to see keep up the good work. the other thing i guess i need to learn is about the caps and resistors.

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