Hi Paul--
Can one make a baffle using high-density foam that will provide
comparable or indistinguishable performance? Its definitely doable.
There are several types of high-density, _open cell_ foam out there.
I tested four or five kinds and found they did pass pink noise with
very slight differences. A neat aspect of foam baffle is it cleanly
passes some sound energy under < 1100Hz to the off-side mic. These
frequencies are critical for time arrival differences. Michael
Billingsley doesn't mention this aspect of the baffle in his SASS
patent as far as I can tell. Would different types of foam make
audible differences? All we need to do is make some up and compare
them to find out.
Cutting and sanding the foam to fit snuggly into the crown housing
would take some time. Vicki Powys discovered that sanding is a god
way to get the final shape and dimensions.
Any open cell foam that has a density of 1.5 to 1.8 pounds per cubic
foot and is at least 4 inches thick should perform to Billingsley's
high frequency absorption specifications. I use "charcoal gray"
acoustic foam. A 10" X 10" X 4" piece should be sufficient to make
a SASS baffle replacement. Measure twice, cut once. Rob D.
=3D =3D =3D =3D
At 11:27 PM +0000 9/24/10, thesilverloon wrote:
>Does anyone know how important using the correct foam for the nose piece i=
s?
>One can buy just the foam nose piece from Crown as a spare part, and
>then build the rest.
>Thats still $100 landed in Australia. But if any closed cell foam
>would work,that would make the project that more do-able.
>
>Regards,
>
>Paul
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