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Old 7th February 2008, 07:08 PM   #1
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Default Can This Noob Mistake Be Fixed

I researched and decided to build small enclosures for the bedroom using the Jordan JX92S full range speakers. WAF was a major factor in the size or the enclosures. My mistake is I made the cabinets in a cube shape. Needless to say they did not sound good. They sounded like a cheap speaker with no enclosure. I added a vent and that helped some. I then removed most of the polyester stuffing and attached carpeting to four of the interior sides (back and three sides). They sound much more balanced, but are now missing some treble.

Internal dimensions are 8"x8"x8" with a 1" diameter vent, 3" long. They are constructed using 3/4 inch MDF. I have also added the series resistor/inductor (4 ohms, 1.5 mH) recommended on the Jordon site for an 8 liter enclosure.

http://documents.jordan-usa.com/jx92_system.html

To improve what I have should I remove the remaining polyester stuffing and/or add carpeting to the one side that is bare? Or is there simply no hope and for good sound and I will have to wait until I build a better enclosure (lesson #1 learned in DIY speaker building)?

Thanks,

Lindsay
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Old 7th February 2008, 07:39 PM   #2
chrisb is offline chrisb  Canada
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Lindsay - in all honesty, unless you've got dozens of hours and dollars invested in a WAF finish on these boxes, I'd suggest you start fresh. Also, it wouldn't hurt to try a different material; for example, 1/2" baltic birch plywood with a couple of cleat braces should provide and adequately stiff box, and if trimming dimensions is really an issue, could shave 1/2" in all directions.


The first question would be, just how small do you need to go? There are several very decent sounding and fairly compact enclosure designs for the CSS FR125 driver, that could probably made to work for the JX92 S:

http://www.planet10-hifi.com/boxes-CSS.html

including a 4.5 liter aperiodic box:

Click the image to open in full size.


link to plans
http://homepage.mac.com/tlinespeaker...odic-plans.pdf


There may well be an even more optimally suited design for your Jordans, but a teeny box may well impose some limitations on performance.

sooner or later that pesky mr Hoffman invites himself to the party.
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Old 7th February 2008, 09:20 PM   #3
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chrisb,

Thanks for the response. I really like that aperiodic enclosure and it would definitely meet the WAF. The cube was just a temporary experiment with materials I had at hand and it will be a few weeks before I can build another enclosure.

It looks like the Jordan JX92S is different enough from the CSS FR125 that the aperiodic enclosure would require a modification and I really have no idea how to do that. All of the plans I found for the Jordans are too big to meet the WAF. So I may just do the 8 liter vented enclosure as recommended on the Jordan Web site, but do a shape more like your aperiodic enclosure adjusted to the proper volume.

Thanks for the links.

Lindsay
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Old 7th February 2008, 09:31 PM   #4
herm is offline herm  United States
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Hey Lindsay,

Are you using a baffle step compensation circuit?

I'm just asking because your description of how they sound
matches what a full-range sounds like without any BSC.

herm
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Old 7th February 2008, 10:35 PM   #5
chrisb is offline chrisb  Canada
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Quote:
Originally posted by herm
Hey Lindsay,

Are you using a baffle step compensation circuit?

I'm just asking because your description of how they sound
matches what a full-range sounds like without any BSC.

herm
Yes, he indicated that :


Quote:

I have also added the series resistor/inductor (4 ohms, 1.5 mH) recommended on the Jordon site for an 8 liter enclosure.
Other factors at play, methinks
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Old 7th February 2008, 10:41 PM   #6
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The only Jordans we have heard were in suspect condition having been subject to some thremal abuse ... we do have a pair of our own on the way (mostly to see what the hype is about, and to answer the inevitable question -- how does it compare to FE127eN.

I have not looked into what the JX92S sims like so can't comment on your box volume -- it is 4.5 litres by my calc -- same size as the FR125 box Chris posted & the same size as the mFonken.

With a box this small and a cube you are going to have a standing wave at ~1k that is going to be hard to kill... i'd suggest putting a fairly dense ball of polyfluff on the back of the magnet as a way to minimize that. Your experiments seem to indicate that side wall reflections are a problem...

If these are indeed just a quick & nasty experimental enclosure, i'd just try the ball of fluff and then move onto another box...

When i get a chance i'll be running some sims... we have a small recycled aperiodic boxes already set up for the JX92 we'll be using for initial breakin, and i'd like to have an idea what to expect. (then they'll go into GMs 48" TL)

dave
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Old 8th February 2008, 12:25 AM   #7
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dave,

The interior is an 8 inch cube which my calculator says is 512 cubic inches or 8.39 liters.

In any case thanks for the suggestion on the ball of poly fluff, I'll give it a try. I am assuming that the internal carpeting and polyester fiber are not causing the problem and can only improve things and that the carpet and polyester fiber have somewhat the same effect. I may try each separately and then together.

Lindsay
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Old 8th February 2008, 03:36 AM   #8
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Quote:
Originally posted by LHMAudio
The interior is an 8 inch cube which my calculator says is 512 cubic inches or 8.39 liters.

Sorry reading too fast... i used that as the external dims.

dave
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