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Bass horn compression ratios

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ceharden View Drop Down
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    Posted: 01 October 2006 at 1:37pm
Hi guys, I'm just finishing designing my 2x15" bifurcated kick horn, you've probably seen odd schematics I've posted.

Question is, what compression ratio do you think is normal for a bass horn and what is liable to rip the driver to shreds.  Thought I'd run this buy you before building a driver killer.

HD15's run with a ratio of about 1.5
1850 Horn is about 1.8
My new horn will be running the drivers at about 2.25 which is quite high in comparison.

Drivers I'll be using are either PD 15SB40 or B&C 12NW76.  I believe both have fairly strong cones, motors and designed for this type of application but they're still going to take some hammering.

Opinions please???





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Mircea Bartic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mircea Bartic Quote  Post ReplyReply Direct Link To This Post Posted: 01 October 2006 at 5:27pm
I think you should do well, If I remember corectly, the design ensures that the cone will not be asimetricaly loaded.
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ceharden View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 01 October 2006 at 6:54pm
Yup, cone loading should be fairly even.

One thing I can't decide is whether the loading and stress on the cone is different if you reverse mount the driver.  On one hand you can just look at it as a piston and since it has to drive in both directions, which way round it is doesn't matter.  On the other hand, maybe the shape of the cone means that it's better at handling a heavy air load on one side.

In a standard horn, which side has the higher air pressure?  The narrow throat or the sealed chamber?  I guess it should be designed such that it's equalised as far as possible.

Really want to get a prototype built.....  Efficiency won't quite match HD15's (1-2dB off) but should be good from one cab upwards which was one of the aims.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb_mike Quote  Post ReplyReply Direct Link To This Post Posted: 01 October 2006 at 9:49pm
The main sources of cone fracture on horns that Ive seen atleast online - was from 'wall of sound' horns ie HUGE cluster,huge horn efficiency.
 
Just build it ,it doesnt sound like an extreme ratio at all.
 
 Considering most people blow up their horn drivers via over powering them,I dont think this is an issue.


Edited by tb_mike - 01 October 2006 at 9:50pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hiphei Quote  Post ReplyReply Direct Link To This Post Posted: 21 October 2006 at 7:20pm
I've stressed my brain over this quite a lot and i think the cone can't be asymmetrically loaded by front chamber at bass wavelengths.. ( I'd say that the air-pressure would be quite even across the 15" cone.. For example @ 100Hz the wavelenght is around 136")

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb_mike Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2006 at 11:21pm
Absolutely.You dont hear of basshorn drivers VC scraping inside due to asymmetrical loading :-)
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