Of course there are nice things about a sphere. For instance, the shape is good at resisting deformation from pressure increases while minimizing material and weight. Anything with flat panels can 'blow up' by flexing, a sphere has to literally expand. So unless it's made of rubber it's a good shape for a pressure container that doesn't propagate sound waves to the outside. And when the wavelengths are long compared to the enclosure the internal shape doesn't matter much.
Well, depending on the way the node is occuring, the sphere could deform out in one or two axis while in on the other, and oscillate like that, no net change in volume, just shape. Could. Think balloon. Just stiffer... or tennis ball when hit, viewed in slow motion.
I suppose that a sphere internally will focus waves hitting the wall, but they won't stop there... they'll be reformed, perhaps with interference and sent back out... resonant nodes can still form.
_-_-bear
I suppose that a sphere internally will focus waves hitting the wall, but they won't stop there... they'll be reformed, perhaps with interference and sent back out... resonant nodes can still form.
_-_-bear
I always figured on using a punching balloon, this way you could tailor your volume to your needs.
You could lay up 3/8" worth of fiberglass really easy and leave the balloon in tact as a sort of rubbery inner coating.
You could even pull the balloon at one end to make a teardrop shape if you wanted.
A continual curve layup of fiberglass 3/8" thick would be RIDICULOUSLY strong and light.
A bit itchy though I guess.
You could lay up 3/8" worth of fiberglass really easy and leave the balloon in tact as a sort of rubbery inner coating.
You could even pull the balloon at one end to make a teardrop shape if you wanted.
A continual curve layup of fiberglass 3/8" thick would be RIDICULOUSLY strong and light.
A bit itchy though I guess.
people keeping talking about standing waves being a problem. as far as i undersatnd, internal standing waves (which are waves canceling themselves out) are actually good when inside the enclosure. however, resonant nodes, like you mentioned would be problamatic.
Standing waves cancel in some spots and reinforce in others, depending on whether you're at a node or anti-node. But indeed, a resonant point can become a 'trap' for that frequency (or a bit lower) when you stuff the space with absobent material. And for low frequencies the shape is irrelevant, it's just an air-spring tank.
Hello, MarkMck did some great experiments and published them here some 8 years ago on the use of an egg shape vs a cube. His results were in favor of the cube shape. He did not however test the teardrop shape used by the Nautilus. I have some teardrop shaped speakers of varying sizes that I have made. What would you recomend for stuffing? I have been using Dacron, maybe fiberglass is more effective. Maybe I should also line the walls with wool felt. These are small spekears ranging from .8litres to 3 litres in size.
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