First Impression: GM's Jordan JX92S MLTL Speaker

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#64
No, it is not a suitable cab for a driver with such different specs. Due to the high Qts, some will argue that it is too high for a vented. For sure it is not suitable for a ML-TL, especially with such a tiny Vas, but FWIW this golden ratio BR tuned to ~65Hz sims nice using published specs:

L = 10.96"
w = 6.78"
d = 4.19"
driver at midpoint
0.75" diameter x 0.75" long vent in the bottom

Of course it rolls off fast below ~60Hz, so EQ will be required to to keep the driver from over excursing.

GM
 
#66
Dear GM thanks for the replies and for all the work you did, I'm grateful to you.

I will try the first option, I do like single drive units and I like the sound of the FR10, I use it in a SOLO TQWP at the moment and it sounds very good (to me)

Every few years I try something diferent and this year I was disappointed with a Buschhorn I tried, made one cabinet and there was so little difference between it and my TQWP I didn't bother to finish the other one.

Regards - Jem
 
#67
You are welcome!

I assume you are referring to Bert Doppenberg's ACR FE103S TQWP. If so, with this driver it has way too much Vb (even more so than the Jordan ML-TL, and why I did not recommend it), so in a sim indicates a large dip in the response followed by a huge peak at Fb. The BSC filter would not help much with this, so I have to wonder how accurate Visaton's specs are.

Interesting, yours is the first bad review of any of the Buschorn designs, though I can not say I am surprised since they are designed for much lower Q drivers. Once Qts goes higher than 0.7, horn design gets interesting and I have yet to see any designs I consider successful.

Anyway, please let us know how the two compare.

GM
 
#68
Cheeshead
About damping
Im sorry its not the back of the driver,but the back part of the enclosure behind the driver,as shown in Jordans web site.
The damping material is one eight inch thick.You glue various sections on ,until half inch thick.Wood glue is good enough.It dampens and deadens sounds behind the driver.
I use the stuffing [polly pillow stuffing],in the vents themselves to finetune voices,especially male.
Remember this is a Jordan transmission design ,with no changes except fore a larger base.
Go to any lumber or flooring store and you will find this damping material.The stuff is used for deadening under hardwood floors,it could be under various brand names.
Joe
 
#72
FWIW, somewhere in all these posts or one of the linked threads there are comments from me that 19mm Baltic Birch, Appleply, or no void marine grade plywood be used and Jay Fisher and friend's subjective opinions on how much better it sounds compared to the MDF prototype he built.

Not being a master woodworker, I have never built a speaker using premium hardwoods, but if the wood is stable and with no voids, splits, etc., then they would be an excellent sounding material to use also.

GM
 
#74
Yo, Blackie!

Yeah, been years now. How time flies whether you're having a good time or not. 🙁

Did you ever build those 40-1197 line arrays, or....?

No s...! I spent maybe 10 min. total doing the various JX92 pipe designs and untold hours in repetitive correspondence. 🙁 Thanks to TJ and Colin though, now I can just point to a link. 🙂

So, been doing anything interesting besides building those wild looking amps?

GM
 
#76
GM said:
FWIW, somewhere in all these posts or one of the linked threads there are comments from me that 19mm Baltic Birch, Appleply, or no void marine grade plywood be used and Jay Fisher and friend's subjective opinions on how much better it sounds compared to the MDF prototype he built.
Click to expand...

I chose mdf for maximum cabinet stiffnes. Secondly I'm going to paint the enclosure so I thought it's better to use MDF which is quite stable. It is easy to make a nice and smooth surface using mdf as it is quite homogeneous material.

I've heard that wood and even chip wood are very good in TL, pipe etc. cabinets because they absorb some frequencys a little and decreace resonances that way. I don't know if it is true but it sound sensible. In my case this is not useful feature as I plan to cover the interior with rubber damping sheets (7.5 kg/m^2). I you think this is not wise, I can cover the interior with 4 mm thick hard felt which I have laying around somewhere.

If you have any ideas how to make mdf sound like baltic birch, please let me know 🙂
 
#77
>I chose mdf for maximum cabinet stiffnes.
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Uh, typical 3/4" MDF has an average MOE of ~527k psi, 19mm 13 ply BB has ~1.8m psi, and since stiffness goes up at the cube of thickness the MDF needs to be ~28.6mm thick to match it. Plus BB ply requires much less bracing than MDF to attain a given increase. This means that the MDF is better damped, but to gain stiffness increases its mass, lowering its Fs, which requires more stiffness, etc., so basically you 'chase your tail' until you get its Fs down below the speaker's effective BW. Might as well cast it in concrete.

Increasing a stiff material damps well due to acoustic pressure falling with increasing Fs, so even if it doesn't damp it all down, at least it requires only minimal extra damping, with the stuffing/lining normally being sufficient, and in the case of a midbass or bass bin, the cab's Fs is well beyond its passband so needs no further damping.
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>Secondly I'm going to paint the enclosure so I thought it's better to use MDF which is quite stable. It is easy to make a nice and smooth surface using mdf as it is quite homogeneous material.
====
True, but it doesn't help performance. 😉
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>I've heard that wood and even chip wood are very good in TL, pipe etc. cabinets because they absorb some frequencys a little and decreace resonances that way.
====
Since TLs typically use medium to high Q drivers, then damp them to a fare-thee-well with stuffing, very lossy construction can work well.
====
>In my case this is not useful feature as I plan to cover the interior with rubber damping sheets (7.5 kg/m^2). I you think this is not wise, I can cover the interior with 4 mm thick hard felt which I have laying around somewhere.

>If you have any ideas how to make mdf sound like baltic birch, please let me know
====
No way to do this AFAIK since we are dealing with the SoS through completely different mediums. The MDF will underdamp the cab somewhat, so further damping will probably be required to lower its Fs, but rubber sheets will reduce cab Vb so I recommend gluing another layer of MDF to them (at least 6mm) and just use some felt as required to damp reflections back through the cone. With the extra MDF layer, only a little to one side and rear of the driver may be required.

GM
 
#78
Thank you for the information. Next time I will use plywood but in this case with the paintcoat and some other unmentioned finishing issues plywood couldn't have been an option.

Ok, I will forget about the rubber sheets. I will apply 1 cm thick high quality felt behind the drivers. Adding more mdf inside the enclosure takes quite a lot room and I already have the pieces cut.

Have you people ever concidered using glass inside the cabinet to stiffen it. 😎

Thank you for all this new and interesting knowlegde. Next time I will build much better speakers but this time this will do since these are my first pair of speakers and it would suck the fun out of DIYing if I achieved perfection at first try 😀
 
#79
You are welcome!

No, I meant to the outside since we do not want to decrease Vb any. These can be measured, cut, and glued on before final finishing. In the future if you want to paint over MDF, build the cab out of one of the plywoods, then add a thinnest layer of MDF available. This will stiffen/damp it also.

Yes, tempered glass, ceramic tiles, or similar attached with non-hardening glue to 'float' them. This is called constrained layer damping (CLD) and works extremely well, but is not needed except in bass, midbass, lower mids high acoustic power designs. My fave for smaller or low power designs are the cheap self adhesive floor tiles, and for a bit more damping, the thicker, more expensive industrial rubber floor tiles attached with non-hardening glue. This is much cheaper than Dynamat, etc., and about as effective to my ears, but I have not done extensive measuring, so as always YMMV.

Anyway, just look around, there's all sorts of inexpensive ways to stiffen/damp cabs and drivers.

GM
 
#80
GM said:
I spent maybe 10 min. total doing the various JX92 pipe designs and untold hours in repetitive correspondence. 🙁 Thanks to TJ and Colin though, now I can just point to a link. 🙂
Click to expand...

As one who lurked through that correspondence and learned a little bit about TL's from it, I thank you, my wife thanks you... and my brother-in-law, who spent a couple of hours sitting in front of them jx92 pipes with a smile on his face after we built them, thanks you! 🙂 🙂 🙂

cheesehead

BTW, I used oak veneer-faced MDF on mine...
 
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