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In the Forum: Horn-Loaded Speakers
In the Thread: Midbass Horns and Real Estate.
Post Subject: Ceiling horn ups and downsidesPosted by tuga on: 7/29/2009
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 Romy the Cat wrote:
Jessie’s comments about my idea to position midbass straight horns from basement, upper- firing and his warning that the horn will get converted into a giant garbage can made me to think. I did not think about it but it is a reasonable concern.  Hypothetically it might be possible to inject in the beginning of the throat a nylon filter that would be catching the dirt but be acoustically transparent at LF…

This all opened for me a box of whole new thigh that I did not have before. Let pretend that I mount two straight vertical horns from ceiling up, in the way how Jessie depicted. A pair of 9” horn with a full 40-45Hz moth have a huge volume and sitting on a  ceiling of let say 900 sq feet room the horns will act as strong chimneys. Sure it will not be any flow across the horn but the horns still will have much higher temperate at throats then at the floor of listening room.

So, this brings a few concerns.  First is the over-drying of the horn’s cone. Second is the expediting of magnet demagnetizing from temperature (ALNOCO magnet of my 10/40-151 are especially valuable). And the third one is the horn constriction with a respect that horn will be working at relatively high temperature. The last one needs further explanation.

The ceiling-hanging horns most likely will not be as solid and heavy as basement-based upper- firing horns as therefore most possibly will be made from wood. The normal construction wood that people use contains 60-80% of moisture. With time goes by the horn dry out, get cracked and so on. So, if a ceiling-hanging horn will be made from wood then the wood needs to be somehow dehydrated.  The people who use wood for sculpture use wood with 6% moisture. I wonder if it possible to cut the horn from 6% moisture wood and then seal it with polyethylene? Anyhow, it is all need to be well thought out…

The Cat



In my view, one other cause for concern would be the possible resonance of the ceiling if the ceiling structure is made wood.
I don't have any experience with all-wood houses but in buildings with masonry walls and wood beams+flooring low frequencies do induce quite a bit of vibration.

As for horn material, why not cast it in a 4 part fiberglass surface and, when assembled, thicken/dampen the outer side of the walls with something dense like plaster or maybe something lighter like papier-mâché?
The fiberglass would definitely give an interesting random-textured surface to the inside of the horn but it would also intensify the "chimney" effect. You could always remove the fiberglass panels, though, after the papier-mâché had dried.

Cheers,
Ric

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