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Paul,

Thanks for the comments.

I may have come up with a way of making the BIG horns fairly painlessly.

I found a place that sells large sheets of urethane foam in several thicknesses and several densities.
And, Its no big deal to find a place that can do laser cutting based on sections generated via a CAD program.

So the plan is to buy sheets of 4 inch thick low density foam, send it to the laser cutter and have them cut out sections (imagine the horn as a loaf of bread), which I would then glue together to achieve a rough horn shape, having a stepped transition every 4 inches.

These transitions could then easily be made to flow, by knocking off the peaks with a SurForm (cheese grater) file, and connecting or bridging from one glue joint to the next, making sure to leave the joints untouched by the file (as they are representative of the original section used to guide the laser cutter).

The resulting smoothed out foam horn could then be laminated with resin and glass fiber from both the inside and the outside. It would of course be too big to fit through the door, and laminating up inside the throat would be a pain, but this is just to illustrate the principal.

In practice I would have each section (which would look like a rectangular frame) cut into four "L" shaped pieces, making it possible to assemble just a quarter of a horn; an object of manageable dimensions, easy to attack with the SurForm file, as well as to laminate, because it is open (no crawling up into the throat). The quarters of the horn would then be bolted together to form the complete horn.

This is a moldless technique... The texture of the glass fiber will be apparent. The guys that used to make surf boards this way spent days sanding and filling in the texture so as to have a clean support onto which they would airbrush images of topless mermaids. Like the other horns, these will be paintd flat black; I will nevertheless keep the fiber glass work as neat as possible.

With regard to resonance, this technique may not yield the sort of "deadness" that masonry or really thick wood might give, but as the foam I've found is not the really rigid (and expensive) stuff, it should make quite a dead core, especially for its light weight.

jd*

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