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Old 2nd June 2007, 07:52 AM   #1
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Default jordan mltl 48

Hello

I am planning to build the jordan mltl 48 design based on the triangle cross section usuing the jx92s. Has anyone any thoughts on this.
Have already found this link
http://diyaudioprojects.com/Speakers...-ONE/index.htm
but would welcome other ideas please. Can I get away with usuing 12mm mdf which I just happen to have but was thinking of making the three corners out of solid wood and rounding them off like a 60 degree semi circle....

Thanks
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Old 2nd June 2007, 11:32 AM   #2
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Hi

How about using the search on this forum

I bet you will find plenty of information about mltl48 and many other JX92s systems.

If you clue two 12mm MDF boards together it will be strong enough.Only one 12mm is too thin even with braces.Many have recomended the baltic birch plywood for the construction.It should sound better,so consider this option.
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Old 2nd June 2007, 11:59 AM   #3
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Thanks for the advice. I did try search but could not find the triangle shaped version.
Will take your advice about glueing two lots of 12mm mdf together or perhaps 12mm mdf with 12mm plywood birch on top.
Do you think the internal diamentions are critical...If the speaker cabinet was slightly larger would that improve the sound or leave well enough alone....
Thanks
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Old 3rd June 2007, 08:35 AM   #4
Colin is offline Colin  United Kingdom
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Hm - interesting site, though the author claims rather a lot for his contribution to the design. The design is the same as the MLTL on the Jordan site, designed by GM. But good to see someone talking about the specifics of building. Note though that he's wrong about some aspects, notably toe-in. The JX92 is designed to toe-in at 30 degrees to get the sound balance and imaging correct.

There are several threads about the triangular version on here. I've contributed to several, having already built the triangular MLTL. Mine used a sandwich of half inch ply and insulation board, which makes quite a light, stiff enclosure. However I'm not convinced it's any better than using three quarter inch ply alone, which is what I'll try next time. I used edge strips to hold the main panels together, resulting in a six-sided external shape. This seemed the easiest way to go when I don't have a proper workbench.

Given the time and labour involved, I'd recommend starting with birch ply of the right thickness rather than messing around laminating 12mm mdf panels together.

The triangular shape does help reduce resonances. I've since built another JX92 enclosure which has a square cross-section and by comparison it sounds shouty on spoken word. Not so noticable on music. Although the design is different, I suspect the majority of the colouration is down to the reflections coming off the back and side walls.
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Old 3rd June 2007, 08:40 AM   #5
Colin is offline Colin  United Kingdom
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As a PS, I can confirm the Tobler author's impressions about corner placement for this design. They sound more balanced away from corners. If corner placement is your only option, go for the 31" MLTL (also on the Jordan site). GM designed this to have a flatter, more accurate bass response.
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Old 3rd June 2007, 09:05 AM   #6
Colin is offline Colin  United Kingdom
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Here you go - this is the thread which kicked it all off. Bruce built most of the available JX92 enclosures and gives his impressions.
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Old 3rd June 2007, 09:42 AM   #7
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Thanks for the advice and where to find the thread.
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Old 5th June 2007, 07:45 AM   #8
Nardis is offline Nardis  United Kingdom
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I rejected the triangular version becauseof its wide panels, and instead I built a pentagonal version with the same cross sectional area as the original, using 18mm MDF.

Internal angles are 2 x 110 degrees, 2 x 90 and 1 x 140.
Internal dimensions are baffle 130mm, sides 101.5mm, rear 106.20mm
External will depend on the thickness of the material.

The advantages of this shape are:
- no parallel sides to reflect rear waves
- narrow panels resonate less
- very narrow baffle (156mm) improves imaging (yes I know not everyone agrees about the JX92 on narrow baffles). It is very close to one of the shapes that Martin Colloms tests out in "High Performance Loudpseakers" with good diffraction results
- elegant looks

Disadvantages are:
- you have to work out the external and internal dimensions of the panels. These vary with the thickness of the material used. (I ended up doing an Excel spreadsheet to cope with this.)
- you need to cut the angled pieces exactly so you need access to a good table saw. (In fact you only have to cut at either the normal 90 degrees or at 20 degrees off the vertical and a with a careful cutting plan you need only a smal number of angled cuts)
- it's tricky to assemble

I adapted Jim Griffin's crossover (I use a Fountek JP3 Ribbon and they are close to the wall) and I am delighted with the sound.

GM's original design and Jim's integration of the ribbon have produced a knockoput speaker.
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Old 5th June 2007, 08:29 AM   #9
Colin is offline Colin  United Kingdom
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Regarding the narrow baffle, I find putting the triangular units back against the walls compensates for th lack of baffle step. If you use your enclosures out in the room, try placing a piece of card or board alongside to hear what it does to the sound. It does seem to make it fuller. I believe there is a link on the site I mentioned above where someone has measured the effect.

Anyway, glad to hear you're happy with the speakers. Sounds like a very elegant design - have you posted a pic of the finsihed enclosure?
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Old 14th January 2008, 05:05 PM   #10
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Can the port be fitted to the rear of the MLTL 48 out of interest ?
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