I've recently gotten a pair of Jordan VTL speakers sporting Jordan JX92s drivers. Much impressed as I am with these speakers, I can't help but wonder what they'll do in a no-compromise design. The VTL's are great speakers to hear and see, but they are rather small, and sexy as they may be, there might be more performance in the JX92s than the VTL can deliver.

A member of Head-Fi.org pointed me to the J-Low. They won't fit in my room though, so essentially, I'll be building a slightly modified version of the J-Low. Dubbed the Smaller Huge J-Low.

I'll be keeping a fairly detailed log here, in case somebody else may want to build it (and because I'd like to be able to read back later where I've gone wrong...).

This is a design made by Nelson Pass. It's a no-compromise, back-loaded exponential horn using the JX92S that stands 1.82 meters tall, 4 cm less tall than I am. The original design is 60 cm wide -- too wide to fit my relatively small room. If I built them from the original design, I wouldn't be able to open the door to my room anymore. To get an idea of how large this thing really is, on the left side is an image from passdiy.com.

And here's another picture from a private builder I found through Google.

Information on this driver can be found here: Jordan JX92S specifications

A quote from that page:

Embracing a range of almost nine octaves, the JX92S offers the widest bandwidth of any single drive unit available. This not only provides an exceptionally smooth, high-definition, crossover-free sound quality but allows for a very diverse range of applications.

The JX92S can be successfully used with all types of enclosures including closed or vented boxes, transmission lines and horn loaded designs. It is eminently suitable for professional near-field monitors, high quality domestic hi-fi, home cinema and custom installations. The unit is magnetically screened, enabling it to be used in close proximity to computer monitors and television screens.

I said earlier that I wanted to see what the JX92s could be in an optimal design. That's part of the reason I want to build the J-Low. Perhaps even more important: I want to build them because they are insane! No, seriously, that is actually a large part in my reason behind building these. Hardly anyone has built these speakers because they are so wife/girlfriend-unfriendly and can't be used in a living room since guests would die of shock. Sadly (luckily in this case), I'm not being held back by a girlfriend (or wife!), and have no living room. Meaning: I can do whatever the hell I want for now, and I'll be damned if I'm not going to take advantage of that while I still can. :evil:

But they're huge!

Indeed. Too huge. I'm missing roughly 25 cm of space, so I need to make them slightly thinner than the original design. After some discussion with Tony from Humble Homemade Hifi he came to the conclusion that it's possible to make them about 15cm's smaller without effecting the sound. The only effect it is likely to have is a slightly less large contact area with the room, which could result in less bass presence and slam. This is hardly an issue in my small room, as they are more than large enough to provide all the slam I'll ever need. The room will be dominated by these speakers anyhow. So, they'll become 45 cm's wide instead of 60 cm, and will be just as tall and deep as the original design.

The schematics

I've modeled the SH-J-Low in Sketchup.
You can grab the Sketchup file here, if you want: http://www.iamrik.com/jlow/jlowslim1.skp

The schematics are based on 18 mm material. I'll be working pre-veneered 18 mm MDF. MDF is brilliant for making speakers. A very strong material and easy to work with.

The top and bottom part mismatch with 1mm since the original design is based around 19 mm (3/4") material. On a speaker this large, I'll be ignoring such a small difference. I can redo the schematic to make up for this single mm, but frankly, I can't be bothered.

Click the images for full size versions.