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-   -   Any enclosure ideas for the "new" JX92S? (http://www.diyaudio.com/forums/full-range/118307-any-enclosure-ideas-new-jx92s.html)

tubesguy 27th February 2008 04:16 PM

Any enclosure ideas for the "new" JX92S?
 
Hi folks -

I just got a pair of the Jordans from the Brian group buy (thanks, Brian) and was thinking of the Jim Griffin designs, with G2Si.

It appears, however, that the measured T-S specs of the drivers doesn't match the specs on the Jordan site. Brian came up with some numbers on his own, and Zaph has come up with some different numbers on his site:

http://www.zaphaudio.com/blog.html

I ran these in WinISD last night, and came up with, as Zaph suggested would be the case, some pretty large enclosures for a vented box. I'm guessing that the MLTL design is also going to be significantly different, and that even a sealed box is going to be quite different with these driver specs.

I am a total neophyte with regard to box modelling, so this is a bit of a reality check with you folks who can do this in your sleep. Any recommended box sizes/alignments/configurations, especially those that dovetail, so to speak, with the new Parts Express box choices? I do plan to use a subwoofer for the bottom end, and can comfortably cross over in the 80-100hz range.

Thanks in advance for any help - Pat

bluegti 27th February 2008 07:06 PM

I implemented the Jim Griffin mini-monitor design using a .25 cu. ft. PE box. My drivers are most likely the "new" version. I received them in December and they have the white boxes as shown in the group build thread.

I have not felt they are lacking in bass considering the size of the enclosure. I have no way to perform any measurements, but at a recent audio meet everyone made comments to the effect of, "its hard to believe how much bass those speakers have".

CSS/XBL 28th February 2008 01:46 AM

Hi,

I have it on good authority that there may be some QC issues with the JX92S. It is also open to speculation as to where on- going production will be done.

Bob

tubesguy 28th February 2008 02:42 AM

Hmm, well it looks like the pair that Zaph tested are very high quality drivers, based on the tests he did, but they are definitely different in regard to the T-S specs, especially Qts, than the specs on the Jordan site.

If there is a concern that there are quality problems within this run of drivers, I'd certainly be willing to run my pair, presumably randomly selected from the batch, up to Zaph to test them. (He's about two hours away from me.)

I'm really just looking for suggestions on how to implement these drivers, insofar as they differ from previous Jordans, and as those earlier enclosure designs thus depart from optimum. - Pat

gmilitano 28th February 2008 12:47 PM

Zaphs results show a nice on-axis FR. If Q is now ~ 0.58, you may want to adjust enclosures designed for Q ~ 0.4. With the higher Q, you may want to consider an Aperiodic Speaker Enclosure.

BWRX 28th February 2008 01:18 PM

Quote:

Originally posted by Bob Reimer
I have it on good authority that there may be some QC issues with the JX92S.
Hi Bob. When you say quality control, do you mean in terms of parameter variation? Because although I trust Zaph's numbers much more than the ones I came up with, the 20 that I measured were all pretty close to each other.

Here's a comparison of the numbers I came up with using new out of box drivers versus what Zaph measured after breaking them in well for 8 hours. Another member said he would measure his pair using WT2 as well. I will remeasure the drivers when I get them back from Zaph to see how much the numbers change.

Code:

    BWRX        Zaph
DCR 5.2 ohms    5.2 ohms
Fs  58.6107 Hz  53.070 Hz
Qms 1.0726      2.1890
Qes 0.3645      0.7826
Qts 0.2720      0.5765
Vas 10.2355 L  11.01 L


Corloc 28th February 2008 02:07 PM

I noticed that Zaph program says SD of 75.43, and Jordan says 78.54. Does the program need SD to work correctly?

Colin 28th February 2008 04:08 PM

According to Ted (I asked last week when Brian's results were up, so the authority is pretty good here too), there is no 'new' JX92S - it hasn't changed and quality control has never been an issue.

The spec differences may be due to different measurement methods. Try the established specs first for enclosure design.

Ted tends to go for a belt and braces method on measurement, using traditional methods to verify what the computer measurements are telling him (ditto on enclosure and crossover design), so I'd be inclined to trust his results.

newtitan 29th February 2008 08:21 AM

my two from the group buy measured (WT3)

at


QTS 0.591/0.598
QES 0.7984/0.8027
QMS 2.276/2.355

cs 29th February 2008 11:18 AM

Quote:

Originally posted by Colin
According to Ted (I asked last week when Brian's results were up, so the authority is pretty good here too), there is no 'new' JX92S - it hasn't changed and quality control has never been an issue.

The spec differences may be due to different measurement methods. Try the established specs first for enclosure design.

Ted tends to go for a belt and braces method on measurement, using traditional methods to verify what the computer measurements are telling him (ditto on enclosure and crossover design), so I'd be inclined to trust his results.

Could the measurements reported be due to the fact that the drivers haven't been 'run-in' ?

That is, will they loosen up with use, which would tend to lower fs and Qt, probably closer to the spec values ?


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