I had a set of Logitech X-230 speakers lying around. I always thought they had a decent sound considering the little money you have to pay for them.
So I wanted to reactivate them, but this time with a slightly modified design. I had ideas for concrete speaker housings in my head for quite some time, so I decided this would be the perfect time to give these ideas a try on the logitechs, in a way of a proof of concept.
Step 1: Designing the Speakers and Modeling the Mold Parts
As I said, i already had some ideas for the design before i started the build. One of them was a square body with rounded edges and a solid concrete top and bottom piece. Each side should look like the other, completely wrapped in black smooth foam to contrast with the rough and cold concrete top and bottom parts.
First I modeled the speakers with every detail completely in Rhino and took some renderings to visualize my intentions. For the modeling it is very important that your new enclosures have the same volume as the original ones for the speakers to sound and function properly. So I dismantled the original housings, removed the drivers and filled the enclosures with water to determine the volume I'll need for the new ones. Simply measure the volume of the water that fits in there and you're done, you could also use sand by the way.
Based on this volume I was able to define the dimensions needed for the new housing. It consists of three parts: a hollow profile with the determined volume that holds the two drivers and a solid top an bottom cap.
Since I needed the negative shape of the housing parts I used the "boolean difference" command in Rhino and got the shapes I needed for making the molds for the concrete. These were then further divided in separate parts to be milled out of styrofoam. The processing of the tool paths for the machine took place in Autodesk Fusion 360.
Step 2: Milling Out the Molds
The molds were milled out of 40mm thick styrofoam. The material allows for fast feed rates of the machine and therefore little time in making all the parts needed. But it is still rigid enough for holding the details and to be filled with concrete later on.
This step was made on my DIY shapeoko-style Desktop CNC mill.
Step 3: Preparing the Molds
For easier demolding I applied a very thin layer of grease on all surfaces that will come in contact with the concrete. Then the separate mold parts were properly aligned and put together with screws. Since they're easily removable after the concrete cured, this will also help for an trouble-free demolding.
Step 4: Pouring the Concrete
The next step was to mix the concrete to a runny texture and pouring it into the molds. Tapping on the molds helps to get most of the bubbles out. I flattened the surfaces by using a wooden stick to wipe off the excessive concrete on the top.
After the molds are poured, attention must be taken to not let the concrete dry out since it needs the water for proper hardening. So I covered the molds with a damp cloth and let the concrete cure for 2 days before i started to demold.
Step 5: Remove the Mold
This is the best part of the process. The mold came off easily and there was just a minimum amount of bubbles. All the details came out nicely and the result was accurate to size.
Step 6: Sanding Some Corners and Edges
I slightly sanded the concrete with 400 grit sandpaper for getting the parts fitting tightly together. I also applied a thin layer of clear lacquer for a nice finish. This will also help to make the fine texture in the concrete more visible.
Step 7: Gluing the Brushed Aluminum Strip
I gave the aluminum a brushed finish by using some 800 grit sandpaper and a ruler (in my case an aluminum extrusion). I used it as a guide for the sandpaper block to sand just in one direction so that the sanding texture is evenly parallel aligned to the extrusion.
Then I used a box knife (the aluminum sheet was just 0.5mm thick) to cut a strip of the desired dimensions and glued it in place. The notch where the strip sits in was already contained in the mold.
Step 8: Moving in the Drivers
I got the drivers out of the old enclosures (they're just screwed in) and glued them into the new ones. The glue will also help to obtain an airtight seal between the concrete housing and the driver. They're also secured with one screw per driver just to be on the safe side.
For the cable I didn't want to reuse the old inflexible one. I wanted something with good haptics. So I got some highly flexible microphone cable that looks and feels much better. Since the drivers aren't too big, the 2x0.5mm² of the cable are sufficient.
When everything was soldered, I glued the top and bottom cap on. I used a lot of glue to ensure that the fit is airtight.
Step 9: Wrapping the Foam
For the speaker covering I used 3mm thick black polyester foam. Since I wanted it to be very smooth and soft to touch I opted for a 80ppi (pores per inch) foam. It's also important to use foam with open pores like they are used in filtration applications. This will allow the sound to pass through the foam with minimum distractions.
After cutting out a piece of foam with the right dimension in the height but a few millimeters wider, I used double faced adhesive tape to hold the foam in place. Starting on the back of the speaker all the way round and finally cutting off the excessive foam to get a nice seam.
And since you need to of these speakers, just start over from the beginning of this instructable:)
Step 10: That's It - for Now!
And that's how these speakers were made.
But this project keeps on going! Since there's still a volume control left to incorporate into this design, I will be continuously updating this instructable as the work proceeds.
And yes, they will also be made out of cast concrete, the volume control sure will have some great haptic and tactility.
If you think that I've made a good work so far, or in the best case got some inspiration out of it for your own projects, you can vote for me in the upper right of this instructable or here!