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Discussion Starter #1 (Edited)
Well, here we go!

Ever since Ricci unveiled his fantastic GJALLARHORN build a while back, I have been dying to build a pair. My desire got even stronger when the folks at data-bass.com measured the beast!!!!

However, I already had a Danley DTS-10 that has served me very well. I really did not want to part with it, but after moving to much more rustic house there was simply nowhere to hide the monstrous monolith.

I thought this would be the perfect opportunity to start building. However, the GJALLARHORN was not much better at blending in with the decor.
So, I embarked on the quest to locate another replacement (or two) that is/are more aesthetically pleasing for the room. Fortunately, I do have a long and low space behind a sectional couch in my hybrid theater room.
I could not find any proven horn designs floating around that utilize an 18 in something long and narrow. I checked other designs and was about to settle for a compromise, possibly a sealed enclosure that would fill the space nicely, but would require much more power.
My thoughts never strayed far from trying to utilize an 18 in a horn and more specifically, the amazing 18" LMS-5400 Ultra driver. It is just such a bonus having that horn efficiency coupled with very low THD.

Instead of compromising, I posed a question in a new thread; is there anyone willing to re-fold the GJALLARHORN into something long and low?
Fortunately, LTD02 took the ball and ran! He along with input from others in this amazing community of bass heads yielded a design that is nearly perfect! Kudos to all those that helped with special mention going to LTD02 for his willingness to share his expertise!

He graciously answered all of my questions and was a tremendous help! He is one of the all-star members of this community.:)

The final design ended up being ~25.5 X 30 X 72 and like the original GJALLARHORN design can be loaded with the UXL-18 or LMSU for best results (and less than optimal options are the Dayton 460 HO and Stereo Integrity 18 HT). The FR is very close to the GJALLARHORN as well, just a revised form factor with a slightly smoother curve and slightly better lower end extension.

After strongly considering the UXL-18 which is a fine driver for much less money, I gave into peer pressure and decided to bite the bullet and add to my LMSU collection.
In doing so, I decided to only build one in the interest of mitigating the cash outlay for yet another LMSU and five more sheets of ply. After all, I am replacing a single DTS-10, which with the help of two sealed LMSUs easily produced 120db+ peaks in my room with so little power and excursion.
And two 72" horns end to end would protrude beyond the end of the couch and designated space by roughly 8-10 inches. Also, as mentioned, this is a five sheet (4' x 8') build and not a trivial wood purchase. Even at $50-$55 a sheet for birch, maple or oak ply, there is a significant expenditure. Also, there is a fair amount of waste with this one due to the long segments. Some of it can be re-purposed in the form of bracing. But, there is still close to a full sheet of pieces left over.
With all the wood in the form panels and bracing, combined with the driver, the weight comes in at over 300lbs...plan on having a friend or two to help with any movement or transport.

Build Cost:
Wood - $275 (using 5 sheets of premium hardwood veneer 3/4" ply, standard 3/4" ply could be used for less than $30 a sheet)
Driver - $925 / $530 (can often be purchased for ~$875 with discount codes, UXL-18 is the alternate driver at $530 shipped or even less via a goup buy)
Misc - $25 (only 3-4 tubes of PL Premium are required, terminal cup is optional depending on orientation, the LMS comes with mounting screws)

Most of the images below are courtesy of LTD02:





Green is the sides, the others are rips down the center yielding the internals and bracing. There is no official cut list for this project. I prefer to cut each internal panel as needed allowing for adjustments along the way. Also, it gives the builder a choice as to how to overlap the panels.


GJALLARHORN (light) vs LOWARHORN (dark) sim:


The internal width can be adjusted slightly if necessary with little penalty;
LOWARHORN at ~25.5" wide vs. 24" wide:

Ringing at around 70Hz is inherent in this design. A sharp cut (high Q, 9 or more db) at that frequency significantly mitigates the problem...or crossing at 60-70Hz eliminates it.
I typically cross my subs at 60Hz, so it is a moot point in my setup.

In the mouth sweeps, TEAL without EQ, PURPLE with some EQ and HPF applied (house curve):


WARNING: A high pass at 13-15 Hz is REQUIRED to protect the driver.
Here is the excursion with only 1200w:

As shown, the driver unloads quickly below ~15Hz.

In case you are running the Behringer DCX2496, the HPF can be set below 20Hz this way:
These are the DCX settings for it (courtesy of Ricci), resulting in a roughly 13.5Hz HPF for this application.
24dB octave BW HPF at 20Hz
24Hz 12dB HP Shelf filter -15dB
20Hz 12dB LP Shelf filter +1.5dB
21.5Hz BP filter Q of 2.0 -1.8dB


http://www.avsforum.com/t/1461489/how-to-extend-the-high-pass-filter-below-20hz-in-dcx2496

Also, if one desires an alternate mouth/exit location, you can try the dual-side firing option as shown below. This will allow additional placement options and orientations.



Don't ask me why LOWARHORN has to always be in caps!


Let the games begin!

Once again, kudos to LTD02 for making this build possible! :) If you choose to build this design, please thank LTD02 for his efforts.
 

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Discussion Starter #2
I did purchase the wood and am 90% complete. I will post pix when I can.


Unfortunately, I am at a standstill as the LMSU is back order and there is no ETA.


I still have to mount the driver, add the braces to the mouth and then add the top.


Damn, it is a beast and heavy!
I will get in approximate position before I add the driver, holy heaviness.



I opted to reduce the width slightly, down to 24" instead of the ~25.5" in the original plans. The 25.5 version is based on ripping the sheets down the center (less the width of the blade).

It is only a ~6% reduction in volume and will help in the shoehorning it into position. The response curve won't be adversely affected.


Original LOWARHORN vs. 24" reduced volume version:
 

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Nice man!So with the 6% reduction in volume how is the response effected or how much do you lose on the bottom?
 

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Discussion Starter #5

Quote:
Originally Posted by Scott Simonian  /t/1502990/joes-lowarhorn-build#post_24018963


Holy crap! You built the whole thing in five minutes?!?!



Definitely want to see how this turns out.

Ha! I forgot to hit SUBMIT on Friday...I went post again and didn't realize it
 

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Discussion Starter #6

Quote:
Originally Posted by gpmbc  /t/1502990/joes-lowarhorn-build#post_24019009


Nice man!So with the 6% reduction in volume how is the response effected or how much do you lose on the bottom?

When LTD02 did the sim with the reduction in volume the response curves were almost identical. In other words, not enough to matter at all.


The response in the sim was very close to the original GJALLARHORN with LOWARHORN having slightly more low end before roll off.
 

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Discussion Starter #7
Here she is, nearing completion.






Triple braces on the driver panel.

I opted to not use deflectors, but rather to extend the braces the whole length of the cab.


Yes, that is me blurred in the background.
 

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Props to you for being the pioneer with this one. Did you do all the cuts yourself, it went together fast?
 

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Discussion Starter #9

Quote:
Originally Posted by gpmbc  /t/1502990/joes-lowarhorn-build#post_24019151


Props to you for being the pioneer with this one. Did you do all the cuts yourself, it went together fast?

Ya, I did it all myself. It was a bear lugging some of those panels. My better half showed up to take some pix and help me carry and wheel it over to the truck to take home.


This go round I took advantage of wood shop with table saw and other amenities that made the job MUCH easier, including a table for assembly.


It is much easier build than the original GJALLARHORN with fewer folds and longer segments.


I used a KREG jig this time too...time saver for sure.
 

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I've been intrigued by the Gjallarhorn ever since I read about it but could never accommodate the size. The refold piqued my interest but at 25 1/2" it was literally too big by over an inch. Now seeing that you sized it down to 24", two would fit flanking the sides of my screen. My only hang up would be assembly. It's gonna be hard to fight the temptation on this one.
 

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wow...that was warp speed.
we were discussing numbers late friday night, so one day and change...


look'n really sturdy too. nice work.


moving them around should be no problem...with a kitchen appliance hand truck. :)

 

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Discussion Starter #12

Quote:
Originally Posted by gpmbc  /t/1502990/joes-lowarhorn-build#post_24019546


I've been intrigued by the Gjallarhorn ever since I read about it but could never accommodate the size. The refold piqued my interest but at 25 1/2" it was literally too big by over an inch. Now seeing that you sized it down to 24", two would fit flanking the sides of my screen. My only hang up would be assembly. It's gonna be hard to fight the temptation on this one.

Go for it!


It is a pretty easy build all in all.

I had Lowe's rip the 4x8 sheets of ply down at the store. That eliminated quite a few cuts and having to muscle the whole 4x8 sheets around, especially on the table saw.

In retrospect, I should have had them cut the two at 72" as well, saving even more time.
 

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Discussion Starter #13

Quote:
Originally Posted by LTD02  /t/1502990/joes-lowarhorn-build#post_24019594


wow...that was warp speed.
we were discussing numbers late friday night, so one day and change...


look'n really sturdy too. nice work.


moving them around should be no problem...with a kitchen appliance hand truck. :)

I didn't want to waste any time. I wanted the get the bulk of it done with the couple days off for the holiday. So, I concentrated my efforts to get it well underway. If had the darn driver I would be done.


We were able to transfer it directly from the build table to wheeled cart at roughly the same height. It made for a super easy transport, so far.

Getting it from the garage to the theater room is going to be a challenge though. Of course, we will find a way, dolly or not.
 

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My experience with assembling a horn sub is the dts 10 where everything was cnc'd. How do you determine the angles of the internal panels?
 

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"How do you determine the angles of the internal panels?"


the angles don't need to be calculated. the measurements set the corners of the internal panels.


the process is fairly straightforward if thought about as starting with a 30" x 72" panel of wood, then drawing on plan. boards are then cut to length depending on how you want them to overlap (butt up against each other) where they meet. since the drawing is to scale, you could even beam it from a projector onto the wood and trace where the boards will go, though I'm not completely sure what i think about that method.



if joe hasn't buttoned his sub up yet, perhaps he could measure the panels that he cut and show his strategy for butting up the ends of the panels as a guide for others to follow.
 

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that should work. there are many proven tapped horns that employ such an approach. but there is only one way to know for sure.


William cowan's big tapped horns have the driver in that position and they model right on hornresp target

http://www.cowanaudio.com/th.html
 

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Awesome work, Joe!!


I have been contemplating a similar form factor for awhile, but I think I want even lower extension. But then, that's another story. I've noticed most people brace their folded horns the way you have, which is plenty strong, but I believe it is heavier than it needs to be. I think with a slight modification to the bracing pattern you can save some time, weight and possibly some money, depending on how the cut sheets work out. I took the liberty of editing your drawing to show the bracing pattern I propose:




By only bracing the yellow sections, all of the panels are braced on at least one side. There really isn't a need to brace both sides of each panel. A brace on just one side is more than sufficient to prevent any resonances in the panel. Furthermore, the braced panel pairs could be built outside of the box (I couldn't help myself...
) with easy access to both edges of the brace for bonding and clamping (brads, screws, Titebond, PL, etc....) without resorting to Kreg jigs and trying to place screws in tight quarters. Additional weight could be saved by cutting out interior port holes in some of the larger braces, but that may be more trouble than it's worth. Lastly, the outlet brace does not need to be full width to stiffen the outer panel of the last segment. A brace with a depth of 3-4" is probably all that is needed to stiffen the outer panel.


I know it's too late for the first build, but you might want to consider these changes for your subsequent builds.


I can't wait to hear your report on how these bad boys perform!!


Mike
 
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