Hi there,
I want to build a multiway speaker. The loudspeaker should get a spherical plastic housing (approx. 50cm diameter). Which high-quality plastic is best suited for this and how do you calculate the thickness of Cabinet?
I want to build a multiway speaker. The loudspeaker should get a spherical plastic housing (approx. 50cm diameter). Which high-quality plastic is best suited for this and how do you calculate the thickness of Cabinet?
How to you plan to make a spherical cabinet of that diameter? Will you have it printed?
Also, why choose plastic?
Actually, plastic is good material for building speakers. It is denser than wood or MDF, with much better damping of resonances (i.e. "dead"). There is a reason why many professional/PA speakers are made of plastic.
Note: not all plastics are equal.
Polycarbonate, ABS, Polyethylene, ...
Calculating thickness is a job for an expert (and choosing the right plastic). Hire one, or just try different thickness (and reinforcing ribs).
Are you sure about that? PA speakers in plastic to me seems like on the low end side with the primary purpose of saving cost and reducing weight and at the same time be more weather resistant compared to what used to be chipboards/ikea style which of course isn’t good either. More expensive PA are still solid ply to my knowledge. But as I said I’m no expert.
How will you get the thick spherical shape?
Better use plastic foam bonded to the inside of a beach ball or exercise ball.
Try making a cuboid speaker in rigid PVC foam first.
Better use plastic foam bonded to the inside of a beach ball or exercise ball.
Try making a cuboid speaker in rigid PVC foam first.
A thick spherical enclosure from many layers of glass mat and resin could be built on a polystyrene foam craft ball. One must first coat the exterior of the ball with an exterior latex house paint if using polyester resin. Once you have a decently thick skin, you could drill a hole and dissolve the polystyrene out with acetone.
Dense is not an asset (unless it is a side-effect of a stiffer material).
Given 2 materials of the same stiffness, the less dense one willmake a better speaker enclosure.
Like paper, there are zillions of recipes for plastic. Some will work some will not.
If you are 3D printing it a more evolved shape than a sphere is suggested.
Most speakers are made from wood because it is easy to build just one. And momentum. Before 3D printers a plastic box was very expensive to tool up for, so one had to be justified that many would sell.
dave
^^^^^^^ THIS will give you the strongest ball, way more than any printing.
I add: fiberglass could be not fully impregnated, just "wetted" in resin, that would make the material "lossy" , dead sounding.
You could cut channels in original styrofoam ball, which will later become reinforcing ribs.
Spheres are strongest shapes/structures with lightest weight, there´s a reason fragile and thin egg shells are so strong.
Not exact spheres but maybe there is a biological reason for that.
Soap bubbles are spherical if left unmolested.
I did a project with a friend many years back like this. We used an exercise ball and coated with heavy layer of 6 inch wide shrink wrap and about 2 healthy layers of chopped fiberglass mat with resin. Then we applied 2 layers of plasti-dip and followed with several layers of fine glass mat, ending up with about a 28 inch diameter, 3/8 inch thick sphere with sort of a constrained layer dsmpening.
The finished product worked very well with a 10 inch coax driver. I was surprised how much better it sounded than the same driver in a standard plywood box. There was very little ripple in the lower midrange, likely from the sphere shape. There was no hint of lower mid resonances from the enclosure sweeping with sine waves.
If I repeated this project and didn't need that large of an enclosure, I would use wood glue or pva mold release. The shrink wrap worked well but was hard to remove.
The finished product worked very well with a 10 inch coax driver. I was surprised how much better it sounded than the same driver in a standard plywood box. There was very little ripple in the lower midrange, likely from the sphere shape. There was no hint of lower mid resonances from the enclosure sweeping with sine waves.
If I repeated this project and didn't need that large of an enclosure, I would use wood glue or pva mold release. The shrink wrap worked well but was hard to remove.
Japanese grow square (ok, "cubic") watermelons; I wouldn´t be surprised at all them growing square eggs too.
Why? .... "Just because they can" 🙄 😛
Only when pressing an egg along its long axis is it difficult to break.
It is the arch shape that gives the egg its strength, in a similar way as it does for bridges.
P.S. How does the chick manage to get out?
Why Are Eggshells So Strong? - Science Connected Magazine
High impact plastics resonates. TPU 65D (hard rubber) is very dead. Polypropylene with GF can be very good - not tested yet in 3D printing because of extruder clogging. Problem is there is no standard how qualify good material and structure.