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Old 29th October 2007, 04:43 PM   #1
ccereda is offline ccereda  Europe
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Default Making Hedlund Horns

Hi everybody,

I would like to make a pair of Hedlund Horns, I have been told that it is much better if the horn is actually curved instead of made out of pieces of MDF.

I also have been told that fibreglass is very good to make loudspeakers.

I would like to know what do you think of the above statements and in case you suggest to make the horns curved how would you make them.

Regarding the plans can I follow more or less the shape or I have to follow strict measures (the plans consider making them with MDF not curved) so I have to vary a little bit.

Thank you

Cosimo
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Old 29th October 2007, 05:36 PM   #2
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Default Hedlund Horns

My son and I made a pair of these horns some years ago using 25mm mdf. We followed the plans with the curves made from straight mdf cut at angles and joined up in the way the plans show. You have to be extremly accurate with your cuts or the pieces do not line up perfectly. We used a very expensive elu saw we had to hire and even then we failed with our first attempt at the curved top panel. Once the front and back panels are cut we glued them up and glued on one side panel and let the glue set before fixing the final side panel. The mdf tends to flex so it can be difficult to keep everythig straight and true. You really need a large flat workspace for assembly. If I was making another pair I would cut the side panels oversize and cut slots in them for the front and back panels to fix into. This gives more security for assembly and glueing but does mean you have to cut the side panels to the final size after glueing. The cabinets are very very very heavy and we had them upstairs in our house so getting them into the room was something I would not care to do to often. The sound of the speakers was superb and was worth the effort but they totally dominated the room visually. My wife was not happy. I now use some tiny floorstanding speakers only (!!!) 1.2m high which if I had not had the Hedlunds in the room I would never have got passed my wife. She appreciated the reduction in size.
I would imagine the curved panels could be laminated from thin ply or even 3mm mfd. you would need to build some sort of jig to laminate on but I am sure there would be some benifit in the final sound quality. There was someone in eastern europe manufacturing these cabinets from fine wood at a very reasonable price and having built a pair from mdf and therefore knowning how much work is involved I would buy the ready made cabinets if I could afford to.
Iain
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Old 2nd November 2007, 01:04 PM   #3
marekst is offline marekst  Poland
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Hi Cosimo,
Making Hedlund curved does not change the profile of the horn much. Hornet Audio makes it with curved laminated wood and supposedly it sounds better – it could partially be due to material used in it.
Hedlund designed the horn for DIY construction. Many audiophiles built a copy and love it. I heard MDF version briefly and I liked it but decided to make something bigger.
If I had to build a Hedlund Horn, I wouldn’t split hairs and do it the Hedlund way. MDF is good for pieces forming the curve; if you have a problem with accuracy, cut the MDF slightly undersized and use caulk when assembling. Pneumatic nail gun makes putting the horn together easer. For the bigger flat pieces I would use plywood.

Working with fiberglass at home is messy, the advantage is that you can make a horn (or speaker enclosure) of any shape. You can eliminate flat surfaces which gives you tremendous acoustical and mechanical benefits. The sound of fiberglass enclosure depends on thickens and the shape of the walls, and composite used.
I have made a pair of fiberglass/metal powder composite Lowther horns - they sound great to my ears. My idea was to make the material heavy, less ringing and less resonant.

For opponents of heavy material, there is always a carbon fiber composite alternative which is already being used to make first class string instruments.

Good luck with your project,
Marek

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Old 2nd November 2007, 06:29 PM   #4
Nortp is offline Nortp  United States
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Default A build method that I used

It is possible to make a curved horn using the build method showed in the pics below.
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File Type: jpg jhorn(4)1.jpg (56.6 KB, 858 views)
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Old 2nd November 2007, 06:32 PM   #5
Nortp is offline Nortp  United States
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Default build pics

I thought that I could post more than one pic, here are some build pics
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File Type: jpg jhorn(1)1.jpg (57.5 KB, 794 views)
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Old 2nd November 2007, 06:35 PM   #6
Nortp is offline Nortp  United States
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Default Having technical difficulties

I need to shrink the build pics to a smaller size so that they will upload, I'll try it tonite, sorry.
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Old 3rd November 2007, 07:24 PM   #7
AuroraB is offline AuroraB  Norway
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Nortp..beautiful build...
But the cross sections seems somewhat different from the original Hedlunds??
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Old 4th November 2007, 07:51 PM   #8
Nortp is offline Nortp  United States
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Default They aren't Hedlunds

That's because they aren't Hedlunds. They were inspired by the Hedlund horn, but I designed them with Martin King's Mathcad models. I made it so that the crossectional area expands in two dimensions not in one as in the Hedlund, and sized them specifically for a Jordan driver. Unfortunately I don't have and build pics on my home PC, because that is what I wanted to show. I laminated 1/4" sheets of plywood to make the horn bodies, used curf cuts to allow the plywood to make the bends and heavy duty construction adhesive to bond everything together. It was fairly straight forward to do, as long as you have some experience working with wood. Didn't need any fancy tools or CNC cutting, just a handheld sabersaw and a circular saw.
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