Please help me fold my horn!! - diyAudio
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Old 30th January 2012, 12:58 PM   #1
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Default Please help me fold my horn!!

Moring all,

I've been playing with hornresp and while I'm getting there with the programme I'm still not making good progress with the folding of a design. I'd been working on a folded tapped horn for 2x KEF B139 and Bjorno very kindly helped with an 18Hz design (home theatre and music) to fit the volume I have

Computers are my nemesis and I've tried to design it on sketchup and gotten nowhere. So I've bought some graph paper and drawn it out, worked fine until I tried to transpose this into reality and started sketching out the horn on some MDF-I spent 5hours yesterday just trying to get the design off paper and onto the MDF, trying to juggle the dimensions so they fitted properly!

Lines on graph paper have no physical dimensions, so while the plan works on paper by the time you make it out of 18mm MDF the internal volume is all wrong and the length has changed-undoubtedly this will adversely affect the performance.

I've seen some of you are exceptionally skilled when using CAD programmes-any chance anyone could get this design into a working CAD drawing for me? The gross dimensions available to me are: 46.5"w x 16.5"h x18.75"d though depth can be increased-which I'm sure it will have to be to accomodate the volume.



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Last edited by TheBaronGroog; 30th January 2012 at 01:03 PM.
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Old 31st January 2012, 01:11 AM   #2
tb46 is offline tb46  United States
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Hi TheBaronGroog,

I have a few questions:

1. Why have the T/S parameters changed from earlier attempts? (It doesn't seem to matter, just interested.)

2. Can the enclosure be taller? (Even a double fold will be in the 51" tall range.)

3. Do you have a sketch for the side view of these speakers? (What I have so far I have not been able to verify, e.g.: Magnet dia, height from mounting flange,.... The width-210mm-seems to be well documented.)

Regards,
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Old 31st January 2012, 04:08 AM   #3
tb46 is offline tb46  United States
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Hi TheBaronGroog,

Here is a first stab at it:

Regards,
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Old 31st January 2012, 10:58 AM   #4
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Quote:
Originally Posted by tb46 View Post
Hi TheBaronGroog,

I have a few questions:

1. Why have the T/S parameters changed from earlier attempts? (It doesn't seem to matter, just interested.)

2. Can the enclosure be taller? (Even a double fold will be in the 51" tall range.)

3. Do you have a sketch for the side view of these speakers? (What I have so far I have not been able to verify, e.g.: Magnet dia, height from mounting flange,.... The width-210mm-seems to be well documented.)

Regards,
Hi Oliver, thank you for your assistance

The T/S changed as Bjorno found the "correct ones"

The enclosure must fit under a a pre-existing piece of furniture. Two of the dimensions are limited so that it can fit under, the depth can be changed as I can bring the furniture out into the room some more (currently in a bay window). So
Height: 16.5" or 419.1mm and FIXED
Width: 46.5" or 1181mm and FIXED
Depth: I could probably get to 25" or 635mm and still keep my crown jewels, a bit more if needed!

I'll get full dimensions of the driver for you tonight. There are some links on here that won't open on my pc-might work on yours? Technical Details of KEF Drive Units

The enclosure you have designed looks great, however I would orientate the drivers the other way, increasing the box height and hopefully allowing the depth and width to be reduced. Less the top and bottom panel there is 383mm or 15.08" height to play with-which will just allow the drivers to be squeezed in vertically

I mailed Bjorno about this and he has said if he gets 5 he'll try and re-model it to fit, so you might want to hold fire before re-drawing again.
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Old 31st January 2012, 11:28 AM   #5
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Baron, I attempted one of these a few years ago, GM was kind enough to work out a design, but it wasn't entirely successful, I suspect more down to my construction than his design, so I'll be interested to see how your project gets on.
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Old 31st January 2012, 01:17 PM   #6
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pinkmouse: What was the issue with your design/build?
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Old 31st January 2012, 02:06 PM   #7
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by TheBaronGroog View Post
pinkmouse: What was the issue with your design/build?
Hi, You probably understand when looking at this comparison:

b
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Old 31st January 2012, 02:20 PM   #8
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Ah, yes, can see the issue there!

Funnily enough pinkmouse's response looks like a clone of one of my attempts to modify your design!
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Old 31st January 2012, 02:24 PM   #9
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Just a thought regarding your box, (sorry if this has been covered before), if you're space limited would an isobarik format work better, or would it compromise the smoothness of the response?
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Old 31st January 2012, 02:42 PM   #10
tb46 is offline tb46  United States
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Hi TheBaronGroog,

Is this what you're talking about (if bjorno doesn't substantially change the simulation, the volume will stay similar, should fit w/ less than 25").

Also, do you want the box to vent forward (as in the drawings so far), or sideways (which would be in the drawing from Post #3: straight down)?

Regards,
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Last edited by tb46; 31st January 2012 at 02:54 PM.
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