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Damping Material Question
(Don Hills) wrote:
In article ,
thelizman wrote:
In theory, it ads 15-25%. In actual practice...well...you can make up
your own mind, but I've never measured any actual noticable change that
couldn't also be accounted for by other factors.
Actually, if you use the right density of stuffing, you do get about 15 to
25% effective size increase. The stuffing slows down the propagation of the
sound waves within the enclosure. The effect is more commonly used to
advantage in "transmission line" style home enclosures, allowing the use of
a shorter line for a given bass extension.
Actually slowing down sound has nothing to do with it this effect (I've
conducted experiments that show up to 36% apparent enclosure size increase ----
1.5 lbs per cubic foot @ 1.5 ft3 enclosure.) It has to do with keeping thermal
conditions in the enclosure closer to isothermal as opposed to adiabatic.
But, so far, all the effects are relative to small signal response ....
Theile/Small parameters. It's time to investigate large signal conditions.
I've got a technical paper
somewhere here with suggested densities for various types of stuffing. I
expect there'll be useful information on web sites that discuss home
construction of hi-fi speakers, too.
--
Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand
1 to 1.5 pounds per cubic foot appears to be optimal and stuffing tupe
(fiberglas, rockwool, wool or polyester) idicates that polyester is as good as
the others and has no disadvantages.
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