New MLTL Designs for JX92S

Fullrange · « **on:** 14 Dec 2009, 03:16 pm »

I saw that the Jordan drivers are on sale at Jordan USA web site, but they also have some new MLTL designs posted there. Has anyone tried them yet? If so I would be interested in hearing about them. They seem to be an improvement over previous designs...

Thanks,

Jim Griffin · « **Reply #1 on:** 14 Dec 2009, 10:45 pm »

These MLTL designs have been optimized a bit vs. the original Greg Monfort 31" and 48" designs of several years ago. My Jordan with a Ribbon 48" version mirrored Greg's work. These new efforts re-run Martin's worksheets to tweak for a lower F3 point on the bass end. I wouldn't call it an earth shaking development but worth the extra few Hzs for the new designs while it essentially maintains the same footprint as previously used. Remember that we are not talking about subwoofer level low bass SPLs with either the older or these new designs. I'm glad that the baffle width is maintained as the ribbon designs. This allows you to take these speakers to a superior level with the ribbon's treble performance.

Fullrange · « **Reply #2 on:** 15 Dec 2009, 03:51 pm »

Jim, thanks for your comments!

Do you know what they mean by reduced floor bounce anomalies?

Jim Griffin · « **Reply #3 on:** 15 Dec 2009, 09:06 pm »

What is suspect has been done on floor bounce is:

Martin's spread sheets now have the ability to analyze a speaker's performance within the room. One scenario is to trade between the vertical location of the driver and the resultant dip associated with the floor bounce. Hence, the floor bounce could be minimized a bit versus just assigning the location of the driver for say minimal on-axis frequency response performance. Hence, you can attain a more perfect in-room response.

Jim

JordanUSA · « **Reply #4 on:** 19 Dec 2009, 10:46 pm »

Hi Jim,

As Martin explained it to me, the capability for room modeling also includes the sound coming from the port. So in an MLTL some of that out of phase stuff, especially if it isn't well controlled by the placement of the driver and the port in the pipe. That is essentially what I concentrated on when doing the new designs, smoothing out the pass band.

It seems that one of the benefits of reducing pass band ripple without using stuffing, is what happens in the 100-1K HZ region in the room. I put together a PDF of the 4 systems and the in room response when the floor is included.

http://documents.Jordan-USA.com/Enclosures/FloorBounce.pdf

It shows the model results for the GM 48" MLTL and the new 40", 35" and 31" MLTLs. I did some in room measurements that seemed to verify that the new designs were in fact smoother in that frequency range. But it's not fair to say that it is an exact science trying to measure it.... My listening impression was that things were indeed smoother in the midrange though.

Mark

Jim Griffin · « **Reply #5 on:** 20 Dec 2009, 04:08 am »

Thanks for the study. The use of Martin's software and its ability to model the speaker's in-room performance gives us new ability to design the best response for our environment. Tweaking the location of the driver and port to achieve better response is very much worthwhile.

I would restate that these plots assume no stuffing. Adding stuffing will smooth out all of these MLTL's (including the original GM 48" version) so that their performance would be virtually flat in practice for the higher order harmonics in the 100-1000 Hz range. Of course the smoother you can make the MLTLs before adding stuffing will necessitate less stuffing and would be less lossy in practice. That is a positive goal to achieve.

A couple general cautions which need to be stated:
I would point out are that a flattened response down to the F3 point may not blend well with room gain. This is why some designers like to have an extended bass response on the low end that smoothly rolls off so that with the addition of room gain one can attain a flat in-room response.

Further these are not subwoofers so accurate reproduction of the 1812 Overture's cannon shots isn't the kind of sound to expect from these MLTLs. Hence, be careful to not overpower these speakers with the anticipation of sub like performance.

JordanUSA · « **Reply #6 on:** 20 Dec 2009, 10:50 pm »

Jim,

Yes, I agree that the modeling capability is great, and many thanks to Martin for pointing out the floor bounce effects to me.

I corrected the label on the plots above to indicate that these were done with stuffing, from the top of the enclosure to slightly below the driver, at a density of 0.25 lb./cu. ft.. I find this to be a good amount.

Over stuffed designs don't sound so good and stuffing lower in the cabinet reduces LF output. So, the above did in fact contain a "typical" amount of stuffing. That is what makes the Second Part of Martin's simulation so interesting. Just looking at Part 1 of the worksheet would leave you with a different impression of performance.

http://documents.jordan-usa.com/Enclosures/FloorBounce.pdf

I doubled the desity to 0.50 lb./cu.ft. and re-ran all simulations. The results are below. Personally I find this to be over stuffed, but the results are interesting in that not a lot changes...

http://documents.jordan-usa.com/Enclosures/FloorBounce2.pdf

As far as coupling goes I guess it depends how you position your boxes in the room. It was easy to position these designs with no apparent boominess, I also recommend less BSC. Room response is very complex, especially in small rooms of varying shape/size...

I agree, there is NO substitute for a subwoofer when you are talking about percussion, symphony or organ! Cannons, kick drums, kettle and tympany drums and the like are not resonant instruments and put out a sinc function in the frequency domain if memory serves me. That function is centered on DC... There is a very real limit to the amount of LF energy that small drivers can produce before trouble sets in.

On the other hand, it is possibe to lower the f3 from say 45 to 30 Hz with very little impact to the driver excursion. I will say, that the benefit is quite pleasant for jazz, blues, chamber and other acoustic music. The following example compares the 48" and 35" designs as relates to driver excursion:

http://documents.jordan-usa.com/Enclosures/WooferExcursion.pdf

I have seen some recent posts elsewhere, recommending that choosing a higher tuning will result in lower driver excursion (and therefore not interfere with the higher frequencies), which is not necessarily true. Just because the SPL drops, doesn't meant that the cone isn't flapping away in a MLTL design. It is still being driven by the signal, you just don't hear it. The best way to limit cone excursion is to remove the LF from the signal.

I suggest we take this off line, I'm not so sure anyone else is interested. I'll email you the complete designs so that you can examine them in detail if you like...

Mark

Jim Griffin · « **Reply #7 on:** 21 Dec 2009, 03:13 am »

Mark,

Thanks for the detailed analysis and the plots. I'm really impressed with what you have done to sort out the details. I'm particularly impressed with the performance of the 35" version as it apparently tunes lower than the 40" version and of course the old 48" variant. You are correct in your conclusions on the superiority of the new designs vs. the older versions. Being able to tune to 30 Hz and have less driver excursion is a very commendable result.

Hopefully, others will make the effort to build several of these new designs. Perhaps the driver sale will convince them to take the plunge.

Jim

Fullrange · « **Reply #8 on:** 21 Dec 2009, 03:15 pm »

Jim and Mark,

Thanks for all of the comments and explanations. It will take me a while to digest some of them. But back to my original question, has anyone built these new designs?

FR

Jim Griffin · « **Reply #9 on:** 21 Dec 2009, 03:32 pm »

Mark may have built a few of these. Perhaps he will comment. I have complete confidence in Martin's software and the results that it derives. Given the modelling done by Mark, I would build the 35" version in a flash. What is not to like about a petite, ~35" high speaker that goes down to 30 Hz on its low end? You will be amazed.

If you want to use the JX92S alone or you can add the ribbon tweeter and my crossover for a sweeter sound.

JordanUSA · « **Reply #10 on:** 22 Dec 2009, 07:09 pm »

Fullrange,

The designs have been posted for less than two weeks now so I doubt that anyone has built them yet, tho I have answered a few questions from people that emailed me. I have built them all and the person that builds cabinets for Jordan USA has built 2 of them.

I don't feel comfortable commenting on them as they are my design, other than to say that they offfer the advantages that are listed.

Perhaps you will be one of the first to try them.

Mark

JordanUSA · « **Reply #11 on:** 6 Jan 2010, 02:00 am »

Hi, I just wanted to post this update.

As some have noted elesewhere http://www.diyaudio.com/forums/full-range/157153-second-generation-jordan-jx92s-mltl-designs-2.html#post2033129, the new 35" MLTL requires very little BSC, a few dB goes a long way when it is located near a corner and toed in as is consistently noted for the JX92S! I found that a few dB is quite pleasant, so 0.5 mH to 0.75 mH with about 3 ohms should be optimal.

As far as adding a ribbon, I put together a new crossover for that! It uses a 2nd order Linkwitz Riley configuration, with 3 dB of BSC rather than the traditional 6 dB from the mini-monitor.

It is equally well suited to 7.5" or 8.5" enclosure widths, uses easy to obtain parts and a much smaller inductor for the JX92S. It also offers the benefits of LR constant phase....

The schematic and parts list can be found here: http://documents.jordan-usa.com/2nd-Order-LR-2Way-Xover.pdf. Enjoy

If you need some assistance in getting components just email me.

Mark at Jordan USA.

Mariusz · « **Reply #12 on:** 7 Jan 2010, 02:30 am »

Hi Mark

I have purchased a pair from your website few days ago.
Your website is great with helpful links and information.
I do however have one question.
Can these drivers be used in backloaded horn design?
I do have some boxes which can be redone to match Jordan drivers and I wonder if anyone use them in such a way (except Pass).

Thanks

Mariusz

JordanUSA · « **Reply #13 on:** 7 Jan 2010, 05:55 pm »

Quote from: Mariusz on 7 Jan 2010, 02:30 am

Hi Mark

I have purchased a pair from your website few days ago.
Your website is great with helpful links and information.
I do however have one question.
Can these drivers be used in backloaded horn design?
I do have some boxes which can be redone to match Jordan drivers and I wonder if anyone use them in such a way (except Pass).

Thanks

Mariusz

There are only a couple such designs that I am aware of in the DIY domain. I am not a horn designer though, so not much help.

Nelson's J-Low and the Tuba by Horst Möller...

Links to both can be found on www.Jordan-USA.com here: http://www.jordan-usa.com/ende.html

If you email me I can probably track a few others down for you. Use Mark@ ...

Mark

chrisby · « **Reply #14 on:** 7 Jan 2010, 06:38 pm »

Quote from: JordanUSA on 7 Jan 2010, 05:55 pm

There are only a couple such designs that I am aware of in the DIY domain. I am not a horn designer though, so not much help.

Nelson's J-Low and the Tuba by Horst Möller...

Links to both can be found on www.Jordan-USA.com here: http://www.jordan-usa.com/ende.html

If you email me I can probably track a few others down for you. Use Mark@ ...

Mark

Martin King or Scott Lindgren might have something up their sleeves as well

Mariusz · « **Reply #15 on:** 9 Jan 2010, 01:37 am »

Quote from: JordanUSA on 7 Jan 2010, 05:55 pm

There are only a couple such designs that I am aware of in the DIY domain. I am not a horn designer though, so not much help.

Nelson's J-Low and the Tuba by Horst Möller...

Links to both can be found on www.Jordan-USA.com here: http://www.jordan-usa.com/ende.html

If you email me I can probably track a few others down for you. Use Mark@ ...

Mark

THX Mark

I'm only asking out of curiosity.
Without a doubt it will sound good in already tried recipes but that is something I failed to do.
However it should be fun playing with them tho.

Best
Mariusz

Mariusz · « **Reply #16 on:** 9 Jan 2010, 01:39 am »

Quote from: chrisby on 7 Jan 2010, 06:38 pm

Martin King or Scott Lindgren might have something up their sleeves as well

Any specifics ?

Mariusz

Mariusz · « **Reply #17 on:** 14 Jan 2010, 04:13 am »

Quote from: Mariusz on 9 Jan 2010, 01:39 am

Any specifics ?

Mariusz

Do not bother ........got it. Thanks for the heads up.
Got my JX92S drivers on Monday. Set them up for burn in for 24h.
Now I am trying to quickly and on the cheap side test those enclosures.
I think that is what you had in mind? (sorry for such a poor picture quality - iPhone camera)

It still needs some work but should be finished by the end of the week.
If it works well, I'll build these out of something more ear pleasing then MDF.

(based on frugal-horn / Jimi Chang + Half-Jimi EJ Jordan JX92s Moose BVR)

Thanks
Mariusz

JordanUSA · « **Reply #18 on:** 31 Jan 2010, 06:06 pm »

Mariusz,

Not sure if you have had time to finish and listen yet, but when you do I would be quite interested in your impressions?

Mark

Mariusz · « **Reply #19 on:** 31 Jan 2010, 07:37 pm »

Hi Mark

Just to clear up few points before I comment on the cabs and Jordan drivers.

-This was more of an experiment then anything else.
-The material used was HQ MDF. I never use quality materials on new projects or prototypes.
-Some tweaking might still be needed.
-No measurements were taken yet.

OK, now the impressions:

The cabinet is relatively easy to build. If someone would choose to build it out of the MDF, the total cost of the speakers would be somewhere around $100-$150 not including drivers ( including glue, dumping material, screws, binding posts, cones, driver seal tape, few cans of primer & top coat etc.).

Before dropping drivers into the fresh cabs I broke them in for around 50h (they have around 100h by now).

One thing that stoke me the most with Jordans JX92S was the resolution these small derivers are capable of and bass extension/tone. I am pretty sure there are many applications where these drivers could be used as well as comparability with more then a few cabinet choices.

I am still playing/tweaking few areas and speculating if EnABLing drivers cone as well as using "Ducting seal" on the basket (dumping) are worth considering.
There are still things I would like to try before voicing my opinion. But at this point, all I can say is WOW !!! .......Very nice drivers that work really great with "Jimi & Half-Jimi" cabs from Frugal-horn website.

If time permits, I'll post some more later and include some pics.

Mariusz