First Impression: GM's Jordan JX92S MLTL Speaker - diyAudio
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Old 31st July 2004, 11:57 PM   #1
abpea is offline abpea  United States
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Default First Impression: GM's Jordan JX92S MLTL Speaker

Several months ago I started building the Jordan JX92S TL cabinet (Kronos Essence clone) found on Jordan's website. Just when I was about done I read a thread on diyAudio about a new cabinet designed for the little Jordan driver that was suppose to sound exponentially better than the TL cabinet I was finishing. I filed the thread away and got busy doing something else.

A couple of weeks ago I was back in speaker building mode and decided to give the new design a run. I contacted GM who pointed me to Jay Fisher who had built the cabinets. I want to thank both GM and Jay for all their generous help and feedback.

GM's design is a mass loaded transmission line speaker. The cabinet is easy to build and because I was doing this as a proof-of-concept project I built the cabinet as simply and quickly as possible which means I used glued butt joints all the way around. The ply-wood was cheap 3/4" six-ply with voids because that's what I had lying around (see attached picture).

When I hooked the MLTLs up to the amp for the first time I realized I had overstuffed the cabinet. After making some stuffing adjustments these cabinets came alive.

The amount of bass GM milks out of these speakers and cabinets is simply amazing! The first day I listened to these speakers for a good seven hours. My play list included the Boston Pops, Jacqueline du Pre' playing the Elgar Concerto, lots and lots of Jimmy Smith, Bill Evans and Stan Getz, Del McCourty, Bella Fleck and other blue grass, Ben Webster, Lester Young, Miles Davis, Coultrane, Evanescence, Nora Jones, Ella Fitzgerald, Led Zepplin, REO Speedwagon, Kansas, Diana Krall, Sade, a great Windom Hill acoustical sampler and Eva Cassidy and others.

The little Jordan was especially sweet on female voices and the acoustical numbers just as you would expect from a quality full range driver. When I closed my eyes I honestly thought Diana Krall was sitting right in front of me the sound was so intimate.

But the best part, the part that astonished and delighted me the most was the bottom end that was coming out of these boxes. Absolutely amazing!! There was one Jimmy Smith song where he pushes the low E(?) peddle on the Hammand B3 and nearly knocked me out of my chair. I auditioned the speakers for some friends and after a couple of songs one of them asked me where the sub-woofer was because they thought I had a sub stuck behind the couch, the bass was that good.

These speakers are easy to build and sound fabulous! Even more the cabinet has a high WAF factor. My plans are to get some good wood and build a real pair of these speakers in the next couple of weeks which I imagine will only sound better with a carefully made cabinet.

GM thanks for an excellent speaker design. These things have a beautiful, full, rich voice that has amazed everyone who has heard them so far.

If you're looking for a fairly compact speaker with a high WAF I highly recommend GM's MLTL Jordan speakers.

Bruce
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Old 1st August 2004, 01:56 AM   #2
GM is offline GM  United States
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Glad you like them and thanks for sharing! The credit goes to Ted Jordan though for specing T/S values that makes it a 'natural' for most cab alignments, and with enough excursion to tune it to a lowish Fs without fear of overdriving it at rated power.

Anyway, I'm looking forward to your comparison of it to the Kronos Essence clone.

GM
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Old 1st August 2004, 02:15 AM   #3
smbrown is offline smbrown  United States
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Can you post the design? Thanks!
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Old 1st August 2004, 03:31 PM   #4
abpea is offline abpea  United States
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Default GM's MLTL Drawings

smbrown,

Jay told me to post his drawings (Thanks Jay!), here you go.

Cabinet front:
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Old 1st August 2004, 03:32 PM   #5
abpea is offline abpea  United States
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Default GM's MLTL Drawings #2

Side view:
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Old 3rd August 2004, 02:10 AM   #6
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The drawings are missing some key numbers. How long and how wide is the port tube? How tall is the enclosed part of the box? How tall is that horn-like area? Is there an MLK worksheet for it?

Added later: I see now that there is a number for the height, but it is too fuzzy (on my monitor at least) to read. Also, I don't know if it is the distance to the floor, or the distance to the bottom of the enclosed area above the horn area. I see a number for "baffle" something, but it's too fuzzy also.

Soo... Could you post all the internal dimensions? I would sure appreciate it.
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Old 3rd August 2004, 08:06 AM   #7
zeno is offline zeno  Europe
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I have build, fairly recently, a pair of Jim Griffiths ported designs. Small bookshelf speakers.

I am not too fond of them, quite a booming bass.

I might try this approach to see if these speakers perform better. Do you have any frequencycurves? And do you use any prefiltering like Jordan suggests to highten up the bassresponse?
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Old 3rd August 2004, 02:02 PM   #8
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by Dave Jones
The drawings are missing some key numbers. How long and how wide is the port tube? How tall is the enclosed part of the box? How tall is that horn-like area? Is there an MLK worksheet for it?

Added later: I see now that there is a number for the height, but it is too fuzzy (on my monitor at least) to read. Also, I don't know if it is the distance to the floor, or the distance to the bottom of the enclosed area above the horn area. I see a number for "baffle" something, but it's too fuzzy also.

Soo... Could you post all the internal dimensions? I would sure appreciate it.
> vent = 2"dia x 5"L

more information here:
http://fullrangedriver.com/tiki-view...ind=&forumId=1

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Brian
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Old 3rd August 2004, 02:18 PM   #9
GM is offline GM  United States
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Quote:
I have build, fairly recently, a pair of Jim Griffiths ported designs. Small bookshelf speakers.
Interesting! I have auditioned JG's originals on several occasions and didn't get this impression, just that they were very rolled off in the LF. Indeed, measurement showed an almost billiard table flat response. Anyway, try tuning them lower or reducing the BSC.

More info, including dims, here:

http://www.fullrangedriver.com/tiki-...ind=&forumId=1

GM
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Old 3rd August 2004, 02:21 PM   #10
abpea is offline abpea  United States
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Default Details

Straight from GM:

+++++++++++++++++

An ML-TL OTOH yields more cab efficiency, something the low efficiency JX92S needs in spades. I know a couple of folks who are very pleased with this one where Vb = Vas and F3 = Fs (assuming SS driven):

L = 31.04"
width/depth = 6.97"w x 4.31"d
driver down from top = 11.14"
vent = 2"dia x 5"L
stuffing = 0.54lb

Since the driver will be well below ear height when seated, extending the pipe down the appropriate amount to get the driver up leaves a nice sized cavity to mass load the cab with kitty litter/sand/whatever. I also recommend a heavy top to further mass load it, as well as a driver brace, such as this tunable one: http://melhuish.org/audio/images/press-screw.gif

GM

++++++++++++++++++

The bottom of the cabinet - below where the port exits - is adjusted up or down depending on where you want the driver to be relative to your listening position. I believe Jay Fisher builds his cabinets so the driver is at the same height or slightly higher than his ear when sitting in his listening chair. I believe GM mentioned he likes to position his drivers much higher which result in a much taller cabinet..

See the thread referenced above in the Full-Range Driver Forum for a more extensive discussion.

I'll also be happy to answer any questions I can to help out.

Bruce
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