Aluminum Dice Cube Subwoofer Boxes

[Dave K.]

Hi all, I am doing a casino themed interior in my 1973 Chrysler Newport. I picked the casino style as a theme because it was unusual (to me) and would force me to be inventive and learn many different skills. I'm going for a fun jalopy style interior not tacky (we will see if that works out. One of the projects I have been wanting to do was create dice cube subwoofer speaker boxes. I was originally going to use MDF, but with the weight and size and the difficulty cutting the dimples to an acceptable depth without compromising the composite was too much for me to figure out.

So I decided to create the dice cube boxes out of .063 3003 aluminum. I had searched the internet for ideas, but was surprised to find that there aren't any like this. I am not much for laying out diagrams, so I will just share how I got to where I am. I am less concerned about the sound quality than I am the appearance. Frankly with kids, the stereo will likely never be turned loud enough to notice the subwoofer performance, so I chose looks over quality. (So did my wife by the way! haha)

I know that I will be using 8" subwoofers that have a total lip diameter of 8.5". Because I will need an 8" hole on one side, I decided to make the cubes 10"x10"x 10" with a one inch border around each edge of the six sides. This will allow me to round a .5" lip edge on each side of the cube give a rounded seem on each side. This 1" space from the edge also helps me align the 'die dimples' consistently across all five exposed sides (x2 as I am doing two sub boxes).

I also found a hypotenuse calculator online. Let me explain: 10" side with 1" edge means that the interior space is actually 8" by 8". My hypotenuse is 11.31. Thus, I could fit three 3" dimples within the center with a 1.15" space between the diagonal dimples, allowing for a reasonable appearance without too much blank space or too large/small dimples. This seemed to be about right size dimples. (3" dimples)

As always, I started off with a cardboard template. Using the "5" side of the die allows me to create the other 4 sides. The side with 6 dimples will be omitted for the hole for the sub (yes I took the easy way out.)

I cut two sheets of 24"x48" 3003 .063 (pre-annealed) from the company I receive metals from, into 10"x10"10" squares. I had to use my beverly sheer as I didn't have a jump sheer or better sheer, so I got some warpage, but will 'fix' them just when I need to.

I used the template to mark out the holes for the 5 sheets of the dice I also had to devise a way to align the pvc 3" pipe (my forming tool) exactly under where I was going to create the dimple in the sheet (blind striking so to speak. I duct taped some 1" 90 degree tabs .25" away from the hole location on the bottom of the sheet which was the wall size of the pvc pipe. Though not ideal, this allowed me to align the tabs correctly to the pipe, to make sure I was aligned correctly. Once the sheet was correctly laid over the pipe I struck the outline of the pvc pipe and sunk in about .50-.75", at least enough to create the die dimple. Again, less than ideal, and I did get some sliding of the aluminum, but not much to be unusable. As you can see I did the 2nd dimple on the "2" side of the first sub box. Only 11 more sides to go! I will keep you posted as I go through the different steps of construction.

I have other aluminum projects upcoming which include a custom aluminum shaker hood scoop and hood for my Newport and an aluminum rear valance as the original steel one rotted off.















Thanks, Cheers,
Dave

[CARS]

That's going to look cool!

You need to follow up on the acoustics. I don't think I have ever seen anything like that. Wood is normally used because it is dense.

[Dave K.]

Originally Posted by CARS

That's going to look cool!

You need to follow up on the acoustics. I don't think I have ever seen anything like that. Wood is normally used because it is dense.

Chris thank you very much! I am rebuilding the car so it will take several months to get it on the road. I will try and find a way to put the subs and boxes into use to let you know how the work. I have no idea how they will sound but I have considered putting something like dynamat on the inside to dampen the vibrations on the metal. The dynamat would absorb some of the bass, but with 2 subs I should still get enoughbass tones. Again, thank you!

[CARS]

I guess my concern would be the enclosure "ballooning ".

A thought for you. Put a port in one of the dimples to turn it into a bass reflex enclosure.

[Dave K.]

Originally Posted by CARS

I guess my concern would be the enclosure "ballooning ".

A thought for you. Put a port in one of the dimples to turn it into a bass reflex enclosure.

Wow, Thank you, I had not thought of that. I think I have come up with a solution for the acoustics, but I will address that later. A friend of mine dropped by this morning and he brought up the same concerns. In our brainstorming, I think I have come up with a workable solution. Will address after the build. Also, I think i will take the subs to an audio installer for testing, and see what they think. Once complete, I will post the results. I am considering taking one with my hypothetical solution, and the other with bare aluminum to see what happens. More to follow. Thanks for the thoughts!

[Dave K.]

This morning I did some more work. I now have all of the dimples in 5 of the six sides, and a relief hole in the 6th side (subwoofer side). I wanted to keep as much metal on the sub side as possible to prevent distortion. I will use my nibbler to cut out the hole when welding is complete. I have gotten all of the edges turned to roughly a 45 degree, and began fixing some of the blemishes I created when making the dimples. Since I am a beginner, I have a difficult time fixing marks and uneven areas that I have created. This is compounded by the dimples and the edges (hard to get tools into positions with out creating more damage). So I worked to smooth out each panel to the best of my ability.

I set up to gas weld the first two sides (.063, 3003 aluminum with 1100 filler wire). I had a difficult time trying to hold the pieces into position for welding. I finally tacked the ends, but the middle rose sharply up, so I just welded the whole seam. Not what I had planned but what I did.











I am now ready to begin tacking the next piece and have pictures for the fitment of the pieces. Not great work, but working through the problems that I encounter.

This has been a great learning experience, working with new shapes in aluminum while trying to solve problems. I will update this afternoons progress later.
Dave

[crystallographic]

Nice concept.
You might want to radius the edges and weld on the radii....? Less distortion, and dice are not sharp on their edges, either.

Also, density of wood/particle board, etc is acoustically helpful, so dense foam is added to metal enclosures .... like the polished shaped sheet aluminum guitar body a fellow made years ago - and had to add foam inside to deepen its sound.

[Dave K.]

Professor White,
Thank you! Will do. I appreciate the input and will take yours and Chris suggestions and find a suitable solution.

[Dave K.]

This afternoon I continued with the welding of the sides. I am on the 1st die, 2nd to last side and was able to get that tacked together. My welds are poor and I found that when I was cleaning the flux off with soapy water, the welds had holes. I have decided to leave off the 6th side for now and grind/sand the existing welds in order to find and address the holes. I was lucky that there wasn't as much distortion from the heat as I thought there would be. Some, but manageable. Here is the current state of the box.
I hope everyone has a great weekend,






Dave

[crystallographic]

Originally Posted by Dave K.

This afternoon I continued with the welding of the sides. I am on the 1st die, 2nd to last side and was able to get that tacked together. My welds are poor and I found that when I was cleaning the flux off with soapy water, the welds had holes. I have decided to leave off the 6th side for now and grind/sand the existing welds in order to find and address the holes. I was lucky that there wasn't as much distortion from the heat as I thought there would be. Some, but manageable. Here is the current state of the box.
I hope everyone has a great weekend,
Dave

.... could be worse.
I think the cubes are saveable.