Building my first boombox

[krilli]

Hahha ... great picture of a spaceship on the blaster! It's upside down though

Fun sound too! Dynamic!

[toxicious]

Looks great!
The spaceship too

What have you made about the cooling? Haven't seen anything on the images?

[tlaine]

What have you made about the cooling? Haven't seen anything on the images?

For short test plays we didn't have any kind of heat sink as we couldn't notice any temp rise in the amplifier. Before enclosing it for the midsummer we just bought the biggest piece of metal we could find and fit in the compartment, drilled holes to it and put some heat paste in between.

The product in question is below (23x95mm).



We were in a hurry so we weren't too picky with the heat sink

The case and the electronics compartment separately are "fully sealed" without any external air vents. We were told that closed acid batteries won't heat and apparently the air in the electronics compartment was able to keep the amplifier cool enough for our 12h+ sessions. One thing to note is that the box was light colored as it didn't have any paint on it and it wasn't in direct sunlight either (there wasn't much sun available unfortunately).

We'll post some proper pics when amsaarin gets them arranged on his disk

Also, we got the back panel locking implemented today, hooray!

[toxicious]

Okay
I am going to paint my boombox black (with some orange details), no dirt spots and so on. It will probably get very hot...but I hope the amp can take the heat, I doubt I will leave it in the sun for hours.

[tlaine]

Here are some new images from assembling the blaster. You can browse them all from http://koti.kapsi.fi/~tl/blaster/img/.


Coping saw was a very useful investment. Here's the device box mouth being sawed, just drill holes to the corners first. The screw holes have been carved a bit so that the screw heads will sink easily in the plywood.


Front panel with plywood pieces for mounting the DT-99 tweeters from front and holes for mounting the SP60 speakers from behind. This way we could get the speakers to same depth and make the look very symmetrical.


Gluing can be a bit tricky with multiple screws as you need to match the screws with the pre-drilled holes that are under the glue.


Speakers mounted to the assembled box. Having an electric screwdriver is a must, also, torx screws rock!


9mm wide window sealing used to seal the back panel.


Assembling the amp shelf from small screws and nuts. The screw heads are glued with epoxy to the holes. You can see the metal piece in background that we used as the heat sink.


The back panel is locked with mounted bolts. The mounts are just some suitable sized L-shaped steel pieces from a hardware store. They are attached to the bottom and top with epoxy and short wood screws. The bolts have been tightened to the L-piece with a nut and washers on both sides. Epoxy is also put everywhere so that it will absolutely not move when the actual lock nut (the pic below this one) is tightened from outside the box.


The mounting points are embedded so that the bolt heads don't extrude from the back.


Here is the full test assembly we used for our four day test run. As we didn't have the locking mechanism implemented yet, we just used a lot of duct tape. Last weekend proved that the design could also work well without any duct tape and in fact also without the window sealing. NOTE 8.8.2011: It turned out that without the sealing the back panel had bended as I had to use more force to close it. Therefore it's a better idea to use the sealing tape to soften the pressure from the lock bolts.


The first layer of paint was applied today. We used black spray paint as apparently it should suit well for our needs. It withstands moisture and is easy to apply. The drawback at least after the first layer was that the plywood texture was still highly visible. We were hoping to get rid of the texture but I guess the next layers will show if that is possible with spray paint

[tlaine]

Hi guys,

I'm finally able to announce that the blaster project has been finished! This is probably the second to last mail regarding this project. We are still writing a short document on what we learned. Until then, here are some final pics from the blaster.



We painted the metal parts in two batches, the screws were in the box when the box was painted, that way we didn't get excess paint to them. The washers and grilles were just painted over a paper sheet. The grilles were painted from both sides.



When painting the effects to the locks, it turned out that you have to use a white base paint as our neon yellow didn't work on black, or at least you would have to apply many many layers.



Here are the speaker holes being painted. As the holes were (too) tight, I had to use sandpaper to get rid of the black paint. Also the wood had apparently swollen a bit during painting so I couldn't get the DT99s to fit without some additional sanding. On unpainted wood the effect paint worked as such and no base coating was needed. Best advice I can give here is that you should avoid manual sanding at all costs, it's horrible.



And here is the final product. It's actually close to what I imagined early on but it looks even better in real life! One feature that is still missing are the embedded UV leds that would really make the neon yellow shine. We'll have to wait and see if that feature will ever be implemented

[amsaarin]

I should add that I did a 150 meter bungee jump today with that particular blaster booming Danger Zone from Top Gun. Even though it was a bit windy, you could hear the sound surprisingly well, even pretty near the top. Awesome, I should say.

[V-bro]

Sooo awesome guys!! Looks really underground! Construction looks ace as well!!

[krilli]

kkkkewl

[gokartnisse]

Those speakercovers are really cool! I would like to have the same in my boombox that i am building right now (almost same setup just 2 more Sp60 speakers, total of 4 sp60). They are just normal computer coolingfan grills right? But which size? I have only found for 80 mm och 120 mm fans, 4 inches is about 100 mm so I'm guessing that neither 120 or 80 mm will fit very well?