I remember reading somewhere that spherical enclosures are ideal
shape..is that correct? debatable?
Incidentally, I live in India where we get *Very Cheap* earthen pots,
called "matkas" which are near perfect spheres with 'mouths emerging
from protruding necks', used for storing water, and they keep the water
inside cool (as they are porous I guess).

I wish to build a speaker enclosure using them, as they are ready made
in various sizes, have an artistic appeal and if the sound reproduction
dose not suffer, It's a very attractive proposition!
These pots or "matkas" have walls which are usually 3-4 Milimeter
thick ( I can get them made thicker).

I did some tries by mounting 8 inch drivers on the "mouth", did some
stuffing inside using polyfill, but the observed sound reproduction did
not seem too "right" to me- I thought it was resonating too much (like
booming) at low freqs. and had a tinny feel to the sound..

Please have a look at the setup he
http://www.geocities.com/madforeagles/DSC01343.JPG
http://www.geocities.com/madforeagles/DSC01344.JPG


My queries are, should I line the insides with some material to make it
air tight? how thick should I get them made? should I use the same
volume calculations for 'normal' enclosures for a driver? should I
stuff it with Polyfill?

Thanks!
Suraj

On 27 Apr 2006 07:07:48 -0700, wrote:

My queries are, should I line the insides with some material to make it
air tight? how thick should I get them made? should I use the same
volume calculations for 'normal' enclosures for a driver? should I
stuff it with Polyfill?

There are a few of issues that I can see. The wall thickness is way
too low - and I'd imagine that earthenware that thin will resonate
really badly. Ideally, I'd probably aim nearer to 25mm if at all
possible, or as close to that thickness as you can get.

The volume that you've used so far also looks too big at the moment -
at least by car driver standards. Lining the enclosure with Polyfill
will actually make this worse, as the surface area of the fibres
results in the speaker "seeing" a bigger enclosure.

I really like the idea though. If it was me, I'd try a smaller
enclosure, with walls as thick as possible. Personally, I'd then seal
the inner walls with coat of fibreglass resin, to avoid any risk of
porosity - if you can't get them made thick, you could use GRP to
thicken the walls at the same time as sealing. I'd then add a layer of
Dynamat or similar just to be absolutely thorough. If you do all of
that, you might start getting some pretty intersting results!

Jon
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