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Stuffing a horn

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tommysb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tommysb Quote  Post ReplyReply Direct Link To This Post Topic: Stuffing a horn
    Posted: 27 September 2006 at 1:32pm
Ok, so I've heard that stuffing a transmission line with wool effectively 'reduces the speed of sound', thus making the t-line appear longer, and reducing the cuttoff.

Can one do the same with a horn, effectively making the horn path longer? If yes/no, why?

Cheers,

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gingerbiscuit69 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gingerbiscuit69 Quote  Post ReplyReply Direct Link To This Post Posted: 27 September 2006 at 2:09pm
no ...... thats just plain stupid! would just muffle it and loose DB!
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adambomb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adambomb Quote  Post ReplyReply Direct Link To This Post Posted: 29 September 2006 at 10:09am
You are correct about the wadding in a TL slowing down the speed of sound (and absorbing higher frequency sounds)... I have a 2 page paper on the subject if your interested...
 
Using this theory for horns.. dunno.. I would have thought it would defo work for Scoops (which are of course TLs)... but I have no idea about horns.. in theory it should lower the cutoff.. but I don't really have any experience with designing horns...


Edited by adambomb - 29 September 2006 at 10:10am
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godathunder View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote godathunder Quote  Post ReplyReply Direct Link To This Post Posted: 29 September 2006 at 5:04pm
adambomb, Id be interested in a little looksie at that paper if you have it in electronic form
LOUDER THAN LOUD
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kevinmcdonough View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kevinmcdonough Quote  Post ReplyReply Direct Link To This Post Posted: 01 October 2006 at 8:08pm
In a reflex box, or in the rear chamber of a horn, then yes like you say the wadding will absorb the sound and slow it down. The sound effectivly thinks it takes longer to reach the sides, and therefore the box/chamber acts as if its bigger than it actually is.

However in the actual horn path of a horn/scoop/TL (or inside the actual path of the ports in a reflex), i would think that it would just block the flow of air and mess things up.

kev
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tommysb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tommysb Quote  Post ReplyReply Direct Link To This Post Posted: 02 October 2006 at 6:15am
Definately works in a T-line, i think sheeps wool at a density of 8kg/m3 is recommended, trying to think which book i read it in (an oldie), but i also know someone who's put it into practise, i think his t-line has an f3 of about 17Hz!
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adambomb View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adambomb Quote  Post ReplyReply Direct Link To This Post Posted: 02 October 2006 at 11:50am

The Loudspeaker Design Cookbook has a few pages dedicated to this...

The paper I have is about the above, but also avoiding standing waves with the enclosure (no panels square to each other, very interesting read)... its just a photocopied article.. so I will have to scan it and post it here for you... might have to wait a bit as my scanner is burried somewhere..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote djtosco Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2006 at 5:39pm
The problem is that the stuffing material increases dramatically the losses... thus reducing the efficiency of the horn!!
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