Yet another Simple and enjoyable Jordan JX-92 Speaker

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#22
Re: answers to question and such

stokessd said:
BrianGT - I looked at your pictures, very nicely done! One comment, have you considered using an air core inductor for the baffle step compensation?

WRT stuffing: the final stuffing density is 6 oz. I didn't model it, but rather used some simple rules of thumb (and some generalizations based on Ausperger's work). The Fs of the driver sets the total like length, and Sd determines the line cross sectional area. I use a 125% to 100% taper. I like the quantity and quality of the bass from TL's with that taper ratio and stuffing method.
Click to expand...

As for building this, I just followed Jim Griffin's design for the ported box. He used a 4 ohm and 1.5mH through some trial and error (he tried 4, 6 and 8 and 4 worked the best). As for the iron core vs air core, I did some research into this. I wanted a low DCR, and the ERSE ironcore seemed to have the lowest DCR, and said not to color the music as typical iron core inductors. Here is the one that I used:
http://www.partsexpress.com/pe/showdetl.cfm?&Product_ID=6917&DID=7

The smaller size also allowed me to fit it easily inside the speaker, unlike low DCR air core inductors. I used a Mills resistor for the 4 ohm resistor. I might try a 4.7 ohm resistor and see what I like better if I have a chance. Here is a picture of my crossover configuration with the drivers:
An externally hosted image should be here but it was not working when we last tested it.

I used 12ga for the wiring.

I have been modeling various TL and TQWT configurations with the JX92S driver, as I want to try a design of my own with the driver. I plugged in your parameters in MJK's mathcad sheets (www.quarter-wave.com), and I don't really get an optimum transmission line at all. Here is what plugging in your parameters:
An externally hosted image should be here but it was not working when we last tested it.


This wouldn't be exactly correct, since it doesn't account for the extra column behind the driver (what would you call this? compression/coupling chamber?). If I put the TL varying from 2.5 (the area of the top) to 1, I get this:
An externally hosted image should be here but it was not working when we last tested it.


If I use the back loaded horn worksheet, making the coupling chamber 5.5" in size with 2.5*Sd on both the closed end and open end, with the driver in the middle, and the horn going from 1.25 to 1, I get this:
An externally hosted image should be here but it was not working when we last tested it.

(not accounting for stuffing)

I have gotten much better response from a ML TQWT.

--
Brian
 
#23
Re: JX-92S

Doug said:
Would anyone on this forum have the voice coil inductance for the Jordan JX-92S as I can't seem to locate it on any of the spec sheets or anywhere on the net.

Thanks in advance

Doug😀
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Doug,

I have also searched for this. From what I can find, it is quite low, and others have just used 0mH to model it for enclosures. This is what I have been doing.

--
Brian
 
#25
Just a couple of quick comments on the stuffing of a TL. Above Sheldon describes stuffing a TL until the double hump impedance curve is damped enough to be a single hump. My experience is that this is too much stuffing. I would recommend designing the amount and location of stuffing so that you maintain the amount of resonant behavior that is needed to produce a deep and flat SPL response. You can see the impact of adding additional stuffing to damp the impedance curve using one of my MathCad worksheets. I think that you will find that optimum stuffing is less then the amount needed to completely damp one hump in the impedance curve.
 
#26
MJK said:
Sheldon describes stuffing a TL until the double hump impedance curve is damped enough to be a single hump. My experience is that this is too much stuffing
Click to expand...

Yes, I remember that I took my 'System IVs' down to the late Doug Dunlop (designer of the now legendary Concordant valve amplifiers).

I had designed "by the book", stuffing until the double hump almost became a single hump. One of the first things that he did was pull some of the stuffing out of the line. He felt that they sounded much better and he was right.

Sometimes too "polite" can sound a bit lifeless.

BTW Martin, I have always used long-fibre wool to stuff the line. I notice that people are using other materials. Could you enlighten us on this point. Thanks.

Steve
 
#29
Hi Steve,

When I built and measured my test line, I used long fiber wool and Dacron polyester fiber. The responses were virtually identical. I dropped wool at that point because I am allergic to it and it smalled like Grandma.

I have also seen measured data on Miraflex (a friendly form of fiber-glass) and it seems to also perform just like the ployester fibers. The only other obvious material that I do not any experience with is the pink finer-glass used for home insulation. I believe that this is a much more effective damping material but also a bit of a hazard so I have avoided using it.

At this time, I have been supplied with some measured data from a builder in the Soviet Union where he has repeated my test line experiment with four other types of fibers. I am still looking at this data so I don't have any real firm comclusions. But I don't see any magic fiber in his data.

Hope that helps,
 
#30
7V said:
The Bandor units are very transparent and I've found them to be intolerant of "boxy" boxes. Now the radiused edges that you guys use will certainly help to mitigate some of the worse diffraction effects (ready for Sheldon's diffraction compensation circuit) but what about internal standing waves?
Click to expand...

Looking at the Bandor specs, their 50ASW/4 looks like it would be an excellent candidate for thinking outside the box. In other words, an open baffle design.

Have you tried any of the Bandors on an open baffle?

se
 
#32
Re: Mathcad sheets

Jarno said:
Hello Brian,

Could you post your MathCad sheets?
Click to expand...

The mathcad sheets are by Martin J. King from www.quarter-wave.com

I have attached the ML-TQWT sheet that I am working on with the JX92S. My proposed cabinet size is: 46.5" H x 6.5 " D x [2" - 10.5"] W.

I haven't changed the voice coil inductance in this sheet yet. It is set to 0uH, instead of 0.2uH.

--
Brian
 

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#33
mathcad?

I downloaded all your mathcad models and the mathcad explorer 8 and I can't seem to get the mathcad explorer to load any modules. It seems stuck on map.mcd all the time (The main navigation screen).

I used mathcad about 10 years ago, and didn't care for it at all. Care to share your algorithms in a non-mathcad way? I'd be willing to do a port to another more platform friendly analysis tool

Sheldon
 
#34
Hi Sheldon,

Since you reside in the US, I doubt the problem is the decimal point and comma problem that I have encountered in Europe. The other problem people have had (myself included) is with the "Script" protection in the Norton Anti-Virus software. This can stop MathCad from working. I would try turning off your anti virus program and see if that helps. I am also assuming that you downloaded the version 8 files. If all else fails you might try a different computer to see if things work any better.

At present, I am very happy with the MathCad program and the way the worksheets can be run for free by just about anybody. I am not really interested in putting the math into a different program but thanks for the offer anyway.
 
#35
Steve Eddy said:


Looking at the Bandor specs, their 50ASW/4 looks like it would be an excellent candidate for thinking outside the box. In other words, an open baffle design.

Have you tried any of the Bandors on an open baffle?
Click to expand...

No I haven't, Steve, but I plan to in the future. I have a feeling that it's one path to Speaker Paradise.

My current project involves designing a speaker system that's as good as I can possibly make it - but in a room friendly and wife-friendly package. I'm currently trying to design the "boxless box". As for the future ...

If you're tempted to try the open baffle, I'd say "Go for it". You could run 1, 2, or 4 units per side in a linear array. You could go 8 units (if you can afford it) but you would need some lift above 8 or 9 kHz. No such problems with 1, 2, or 4 units. With 4 units you couldn't stand up and listen; you'd have to remain seated - but it would be worth sitting down for.

Having chosen the number of full-range units per side you could run them full-range or cut them off very low, say 100-250 Hz and go to a bass unit. The crossover, if you have one, could be well below the mid-range. The Bandor 150 would make a good bass partner.

Well, enough rambling on, just some ideas, you'd probably prefer to make some discoveries yourself.

Anyway, I'm visiting Bandor tomorrow. I ask if they know if anyone's done an open baffle and report back.

Steve
 
#36
MJK said:
Hi Steve,

When I built and measured my test line, I used long fiber wool and Dacron polyester fiber. The responses were virtually identical. I dropped wool at that point because I am allergic to it and it smalled like Grandma.
Click to expand...


Thanks very much for that, Martin.

I just had a thought, reading about the wool smelling like your Grandma ...

Could we come up with a suitable, sweet-smelling lacquer? You'd just spray it on the wool. Not only would the solution audibly improve the quality of the bass, it would also keep off the moths and attract women.

Can you see a market for such an elixir?

Steve
:devilr:
 
#37
Steve,

I have a wife and two young daughters. I love them a lot but my son and I have enough women telling us what to do already. I am constantly being reminded that I am the village idiot.

But your idea does have some merit, maybe we could change the smell to be more like beer and BBQ.

Martin
 
#40
Yeah!

Ouch!....Ouch!....Ouch!.....
 

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