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In the Forum: Audio Discussions
In the Thread: Loudspeakers and headphones
Post Subject: Driver and throat dia [Re: Fostex, compression driver MF, aliens and SS [Re: Ronnie's horns]]Posted by Ronnie on: 12/2/2005
Hello John,
The woofer is Fane Studio 8M and throat diameter on the 115Hz horn is 5.56".
The initial 4.5" depth of the throat is made up by 6 MDF pieces with rough edges (awaiting bondo smoothing).
I can easily add 3/4" pieces to the throat section to make it longer and the diameter smaller.
Here's how I calculated the proportions, with help by your formulas:
13592.48 inches per second / (2 X 48.865 inches)) = 139Hz (much lower with room boundaries)
length = 30.125"
eff.length = 18.74 + 30.125 = 48.865"
throat radius = 2.779472"
throat dia = 5.559"
...compared with how I understood that Romys horns are built:
13592.48 inches per second / (2 X 48.865 inches)) = 139Hz
length = 31.7
eff.length = 17.165 + 31.7 = 48.865 inches
throat radius = 2" (1.98")
throat dia = 4" (3.96")
Interesting to hear about horn size matching. A 7-800Hz horn sure would seem tiny on top of the 115Hz.
I have lots to learn about speaker-room interaction and about everything else about the setup. 
Have ordered some "Furniture sliders" to place under the horns, which just might make it possible to move them. Compared to my old Paradigm Atom boxes (hehe), I have noticed how little the sound changes sitting up close or far away from the horns. Only with my head right against the back wall is there any very big difference.
/Ronnie
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