jordan mltl 48

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planet10

planet10

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Re: Stabilty of Jordan MLTL

Jim Griffin said:
Those of you who are concerned about the stability of the Jordan MLTL could do as I have on my Jordan with a ribbon MLTL design. I use a base to wide the stance so that the floor contact is spread out. My base is Corain--a man made stone like material which can be machined. Other ways to add stability is to add weight to the bottom of the enclosure, use spikes to bite into carpets, etc. Several ways to achieve stability for your MLTL. Stability is a problem that can easily be solved. This should not be a reason to select another design.
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Also, one could add a fixture so that they could be screwed into the wall at the top. (as i understand it, these like to be up against the wall -- if not i'll let you know once ours are built)

dave
 
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abpea

Member
Joined 2003
Re: Stabilty of Jordan MLTL

Jim Griffin said:
Those of you who are concerned about the stability of the Jordan MLTL could do as I have on my Jordan with a ribbon MLTL design. I use a base to wide the stance so that the floor contact is spread out. My base is Corain--a man made stone like material which can be machined. Other ways to add stability is to add weight to the bottom of the enclosure, use spikes to bite into carpets, etc. Several ways to achieve stability for your MLTL. Stability is a problem that can easily be solved. This should not be a reason to select another design.
Click to expand...

I agree, stability for this cabinet is a simple problem to solve. For my 48er I found a nice full 2 1/2" thick plank that I cut into lengths, put a fancy routed edge on them, painted them black and added spikes for the carpet. Bolted them to the bottom of the 48er column and it is solid as a rock, or Corian, etc. :)

You will have one problem with these speakers... people will keep trying to take them, or get you to build them a pair. They're great, build a pair you'll be glad you did!!

Bruce
 
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Colin

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Joined 2003
ejjordan.co.uk
I don't think there is a folded 48 design - this was just an off-the-cuff idea. I agree, the stability is a problem to be solved, hence bolting to wooden floors in my case.

PS to Planet 10 ... I know what you're like for modifications. I am definitely waiting until you've reported on your build before commissioning mine.
 
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Colin

Member
Joined 2003
ejjordan.co.uk
Yes, the 48 started out specifically to get the driver to ear height without needing a stand. Maybe one of the compact horns (hifisound.de) would be a better bet if you want a short, rectangular enclosure?

The 48 does look very elegant when placed back against a wall, especially in triangle format. (I haven't seen a pic of the pentangle.)
 
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Nardis

Member
Joined 2003
The 48 does look very elegant when placed back against a wall, especially in triangle format. (I haven't seen a pic of the pentangle.)
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It's a pentagon, not a folk-rock band! Shown here before its top was bolted down.

I wish now I had put the port at the rear. Its sound never ceases to amaze me as I go through source and amplifier upgrades. Thanks to GM for the original design and Jim for the xover starting point.
 

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planet10

planet10

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Colin said:
PS to Planet 10 ... I know what you're like for modifications. I am definitely waiting until you've reported on your build before commissioning mine.
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I probably won't be able to resist, but for the short term the idea behind the JX92s is to see how badly they get spanked by the FE127eN :) (i'll be happy to be surprised thou)

With Ron really starting to make progress on actually figuring out the physics of EnABL and Soong so up on the JX92, i'll probably just let them work out the treatment for the 92.

Also with the bifurcation of Jordan with Ted funding his retirement, i'm going to sit back a bit and see how things shake out before seeing were they fit with the business ends of things (i do have a set of the "rogue" 50 mm headed this way to play with :) Hopefully new blood & competition will spur the products forward so that they become better & more affordable (that last probably just tied in with getting the volumes up)

dave
 
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Nardis

Member
Joined 2003
Colin said:
folk band or military industrial complex, they still look nice speakers.
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Thanks Colin

I have been racking my brains for a name but neither "The Pentagons" or "The Military Industrial Complexes" sit comfortably.
They remain "Pentagonal Versions of GM's 48"MLTL (with a ribbon added)". I did think of calling them "GM's Wonders" but decided it sounded too like a variety of potato.

I haven't managed to hear either standard or triangular versions of the design. although I have heard a number of DIY JX92 projects. Where these theoretically have an advantage is narrow baffle (155mm), narrow panels for less resonance and no parallel reflective surfaces. Is there anyone in the London area with the rectangular or triangular designs who would like to do a comparison?

The cabinets were inspired by the Pentachord, a very slim, tall design using little Bandor drivers, that I heard at a HiFi show at Heathrow, London many years ago. I designed a pentagonal shape with the same CSA as GM's MLTL. Cutting isn't as tricky as it looks if you have a table saw. All the cuts are either 90 degrees or 20 degrees. Clamping for assembly is the difficult bit.
 
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Colin

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Joined 2003
ejjordan.co.uk
I remember the Pentachord - that had Bandor drivers and sounded good. I attended one of the shows in the 90s which had several Bandor systems on demo. The Pentachord was the simplest and, IMO, the nicest sounding.

Yours look quite B&O. Perhaps they should be called the high five ...

Elsewhere on the forum there has been a thread about steel enclosures. This shape would look good in metal, if anyone was brave enough to try.

Do you use the standard BSC circuit which is part of Jim's crossover or have you altered it to compensate for the narrower baffle?
 
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Nardis

Member
Joined 2003
Elsewhere on the forum there has been a thread about steel enclosures. This shape would look good in metal, if anyone was brave enough to try.

Do you use the standard BSC circuit which is part of Jim's crossover or have you altered it to compensate for the narrower baffle?
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I did hear some JX92s in a sealed 25 or so litre curved cabinet made of 2 layers of aluminium with an injected polyurethane foam filling and a plywood baffle. They were superb.

Metal doesn't appeal aesthetically to me, but I am in the process if costing out Corian and its more acoustically inert variants. If I can find somone who gives me a reasonable quote I will let people know. A good proportion of the expense is apparentlly in programming the CNC cutter used, so the unit price drops and the more takers the cheaper they become It may even be possible to give the cutters a CAD file if we can do it in the right format.

As for the xover, I used Jim's as a basis, took out what I thought were the BSC elements and then basically tuned it by ear until it sounded right for the position in my room. I had used an online BSC calculator to help, but I can't remember the link at the moment.
 
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Nardis

Member
Joined 2003
I remembered the BSC calculator I used. It's on Martin King's Quarter Wave site and is an Excel sheet by Hong Nguyen.

http://www.quarter-wave.com/General/BSC_Calculator.xls

I used this to work out roughly the BSC element in Jim's xover given his baffle size, deducted it from the xover values, recalculated it for the narrower baffle and used the table of results to start with a very small correction given I was very close to a rear brick wall. In the event I decided that I needed very little BSC, as it came to a fine balance point between a fuller-bodied sound and bass boom due to room modes. At this point I settled on the slightly lighter bass.

Since then I've been involved in amplifier issues and when they are sorted out, I will retune the xovers. if they need it. I've been looking at doing this with a passive line level filter based on

http://sound.westhost.com/bafflestep.htm

which should give me finer control with neglible losses. Has anyone used this?

I have to be careful of losses as I am running the MLTLs from a chinese 300B SE 9W per channel amp (bought on Ebay by getting up at 4am to slam in a last-second bid). It sounds superb but I can't afford to lose more headroom on the xovers.
 
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Nardis

Member
Joined 2003
GM said:
With a 300B and near wall location, I'm surprised you need more than a Lpad on the tweeter.
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Yes. You may well be right.
Oddly enough I just encountered a piece in the UK magazine HiFi World Feb 2008 issue suggesting using the Fountek JP3 ribbon (which I use) as a super-tweeter with a full range design they have published., and other full range drivers or designs with tweeters rolling off just above 20k..
They have a circuit which boils down to a cap in series used as a 1st order high pass filter and a variable L-pad.
I think I have the appropriate values, and it’s a wet weekend……
 
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Nardis

Member
Joined 2003
Nardis said:


Yes. You may well be right.
Oddly enough I just encountered a piece in the UK magazine HiFi World Feb 2008 issue suggesting using the Fountek JP3 ribbon (which I use) as a super-tweeter with a full range design they have published., and other full range drivers or designs with tweeters rolling off just above 20k..
They have a circuit which boils down to a cap in series used as a 1st order high pass filter and a variable L-pad.
I think I have the appropriate values, and it’s a wet weekend……
Click to expand...


Well, the wet weather continued and I tried running the MLTL full range with the Fountek rolled in above 12k and also above 16k. The amount of detail improved, but this was not entirely surprising given that the signal was not going through 50 feet of copper inductor. The top end was hard verging on harsh.
When I switched back to Jim's design the whole presentation improved, and it became smoother and much better integrated. I definitely preferred the music using the 3k xover based on Jim Griffin's design .
 
J

Jim Griffin

Member
Joined 2003
t-head,

The 48" MLTL with the JX92S has a 37 Hz 3 dB down low end without considering any room gain. This variant will edge out Ronnie's design for bass impact and you can DIY the cabinet. You get DIY satisfaction while saving hundreds of dollars. What is not to love about that?

My version of this 'Jordan with a Ribbon MLTL' design (actual about 46.5" long) adds the superb Aurum Cantus G2si ribbons which are excellent above 3000 Hz. Just ask Nardis a couple of messages before this one how he likes his version (albeit with a similar Fountek ribbon).

Jim
 
T

t-head

Member
Joined 2007
Hi Jim,

I bought from Ronnie before I ever discovered DIY. I have heard good things about your designs and certainly meant no disrespect. I have another pair of JX92Ss coming thru the group buy...when they arrive I'll be in touch...;) But all that notwithstanding, Ronnie makes a great pair of $1250 speakers for the hopelessly non-diy types...

t
 
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