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Old 2nd May 2008, 06:35 PM   #1
duck1 is offline duck1  England
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Default need help designing 15" folded horn.

Hi,
I have 6 JBL 2226H 15" drivers for which I intend to use as the bass element in a system I'm building. I want to go down the horn route but am not sure what would be the best suited design for these drivers. I intend to run some sort of kick bin ( like HD15) above them so response above 100hz probably won't be necessary and low end around 40hz ish would be nice. I intend to run 3 per side, so with mouth coupling they should get reasonably low? Does any one know of, or have plans for an existing design in which these drivers will fulfill this role or do I have to go down the Design route? I have a rough design drawn up but as I'm no expert, I am a bit reluctant to go off building boxes that may well sound crap and and could damage the drivers? Any comments or advice would be gratefully welcomed. The drawing I have come up with is basically (I think) an exponential flare starting with a throat of 398cm2 with a length of 215cm to a mouth of 4071cm2 I think this roughly equates to a 1/4 wave @ 40hz I have squeezed this horn into a box that has a frontal ( horn mouth ) area of about 93.6cm width x 46.8 Height and is about 87cm deep Which is fairly big! Cheers.
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Old 2nd May 2008, 08:38 PM   #2
Horexx is offline Horexx  Germany
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Hi Duck1,

this horn http://www.egbeck.de/15bhorn0.htm
gives a good and save performance with a smooth frequency response. I have used two per side. with 18Sound speakers. There is a lot of power.

For the JBL2226H the back chamber should be slightly reduced.

Horexx
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Old 4th May 2008, 07:03 PM   #3
duck1 is offline duck1  England
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Thanks Horexx. looks similar to old Fane 18" design. there seems to be quite allot of wasted space in the box? The response looks pretty flat with such tight folds? I could probably trade some of the upper bass for more low end- and greater power handling? Cheers for the suggestion. Duck.
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Old 4th May 2008, 07:41 PM   #4
MaVo is offline MaVo  Germany
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A good place for this kind of speaker is: http://www.speakerplans.com/
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Old 4th May 2008, 08:23 PM   #5
Horexx is offline Horexx  Germany
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Duck1,

there is wasted space, but the folding is straight forward and how should it be omitted?

I use the horn up to 500 Hz. I have slightly modified the folding, so that the acoustic waves are reflected. better.
(The upper frequency limit is not restricted by the lower end but the volume between cone and throat has influence beside the cone mass and other factors.)

My speaker in this horn showes no power limits (ca. 110 dB/W/m and 400W per speaker)

I used Hornresponse for some simulations.

Horexx
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Old 4th May 2008, 09:06 PM   #6
duck1 is offline duck1  England
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Hi Horexx, What I mean by lowering the upper limit is that if I give the speaker less program frequency to handle, then its power rating in the narrower pass band will be higher? i.e 150hz range will use less power ( and therefore will have greater headroom) than 450hz range. Is this correct? Because I want to try and get down to 40hz I would try to use all the available space in the box to get the horn length as long as possible. what do you think?
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Old 4th May 2008, 09:09 PM   #7
duck1 is offline duck1  England
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Hi MaVo, I've looked on speakerplans but there's no 15" folded horn design on their site? only HD15 which doesn't go low enough for what I want. I will probably use HD15 or similar for upper/kick bass though.
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Old 4th May 2008, 09:20 PM   #8
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Default You can make the wasted space go away but...

the California is about as clean and compact a design of this type as you are going to find. There is some need to balance practical construction and what you see as wasted space. Take a look at William Cowan's Tap horns on his site. You won't find any wasted space there.

http://www.cowanaudio.com/
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Old 5th May 2008, 01:34 AM   #9
Horexx is offline Horexx  Germany
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Hi Duck1,

your thoughts about power handling I do understand better now.
I had tried to find a better folding - and have resigned :-(
I had tried to follow Dr.Bruce Edgars thoughts about bending:
http://www.volvotreter.de/dl-section.htm

Hornresponse by David McBean calculates the volume (netto), good for comparisons.

Horexx
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Old 5th May 2008, 01:48 AM   #10
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Default Horexx can you post...

your reconfiguration of the Beck design (California) I would be interested to have a look. That;s a lot of bandwidth from a 15 inch driver. You can PM the details if you like.
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