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Owen's Dual UXL-18 Sealed Build

22K views 50 replies 8 participants last post by  Owen Bartley 
#1 ·
I've been really looking forward to the subwoofer part of our eventual basement build, and I finally have made progress on that front.

I knew for a long time that I wanted to try a sealed approach this time, having had 2 different ported subs before (and currently). I thought I'd go for a pair of big ones, and when the opportunity came up last year I jumped on a group buy for a pair of Mach 5 / IST UXL-18s. These things are hand built in Canada by @mrogowski, and are extremely capable drivers. 34mm xmax, 1,200w power handling, 65lbs of woofage, and I now have a pair of them. :grin2: Just for reference, on pure displacement capability, I think a single one is capable of about 2.7 times what my Tempest can move.

I fiddled around a lot with enclosure sizes, WinISD graphs, and checking other peoples builds, and I settled on exterior dimensions of 20(w) x 20(d) x 22(h) for an effective net internal volume of about 3.3 cubic feet which should be very reasonable for this driver. I'll be using a MiniDSP on the pair in the final setup, likely working in a Linkwitz Transform to bring up the bottom end. Power will be from an iNuke 6000 (non-DSP), one sub per channel. Below is an approximate comparison of my existing SDX-10, Tempest, plain sealed UXL, and the same UXL with an LT applied.
 

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#2 ·
After a lot of calculation, speculation, and general sitting around doing not much, I've finally made some progress with real tangible results.

My drivers came in (boy, are they heavy!) and arrived in good condition. My junior inspector seemed excited to get them... but it turned out he just wanted to play with the packing material. They sat around in their packing for quite a while, because I didn't have an amp for them, MDF for them, or time to actually DO anything with them. Eventually I picked up an iNuke 6000 (non-DSP), and hauled out the MDF sheets I had buried in the garage, and got to work.

Where to start? First impressions I suppose. Until now I have owned an original 15" Tempest (which was a monster, especially to me, back in 2006 or so). These things are straight up beasts in comparison. The carbon fiber cones and caps are beautiful, and the big fat surround is impressive, to say the least. The magnets are huge, and did I mention they're HEAVY? I know there are bigger drivers out there now, but these are still right up there. Build quality seems very good, and I found no issues with a visual inspection on arrival. Mark does great work, and I am very excited to have 2 of his exceptional drivers in my theatre.

I will be using Speakon connectors, so to get any kind of a signal to the subs, I had to put together the enclosure connection terminals. A little bit of soldering, and some quick and dirty heat shrink, and they were ready. My senior inspector enquired about modifying some settings before going off to bed, and had his request denied. Lol. When I did have the opportunity to set up a quick test with the iNuke, everything worked the first time out, which is always nice. In free air, sitting on the floor, with limited power after the kids were in bed, my wife could still hear "Bass I Love You" from upstairs. I had a bit of hum at higher gain, but I'm not worried about that for now since the setup for the theatre will be completely different.
 

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#18 ·
After a lot of calculation, speculation, and general sitting around doing not much, I've finally made some progress with real tangible results.
From the looks of it right now, I'd say your calculations and speculations are paying off nicely! I mostly do the sitting around part (lol). Anyway, I'm loving the updates and pics! Please keep 'em coming.

Where to start? First impressions I suppose. Until now I have owned an original 15" Tempest (which was a monster, especially to me, back in 2006 or so). These things are straight up beasts in comparison. The carbon fiber cones and caps are beautiful, and the big fat surround is impressive, to say the least. The magnets are huge, and did I mention they're HEAVY? I know there are bigger drivers out there now, but these are still right up there. Build quality seems very good, and I found no issues with a visual inspection on arrival. Mark does great work, and I am very excited to have 2 of his exceptional drivers in my theatre.
I'm excited, too, and they're not even mine. Please forgive this noob as I don't want to derail your thread. And I'm not looking for a lesson in Designing Subwoofers 101 - just curious about some basics. Do you subwoofer DIY'ers have a secret decoder ring for estimating your lowest usable output? Is that known as the f3? I'm thinking the light blue trace in the graph up top is what you're after.

My junior inspector seemed excited to get them... but it turned out he just wanted to play with the packing material.
:jump:

I will be using Speakon connectors, so to get any kind of a signal to the subs, I had to put together the enclosure connection terminals. A little bit of soldering, and some quick and dirty heat shrink, and they were ready. In free air, sitting on the floor, with limited power after the kids were in bed, my wife could still hear "Bass I Love You" from upstairs.
Now who's playing?! :jiggy:


The driver is bigger than your helper! :clap:
Excellent build thread.
....here's my helper holding up the baffle.

Come to think of it, car rims come in 18" diameters, too :rubeyes:!
 
#3 ·
Now that I knew I had working subs and amp, it was time to start the hard part and do some work. That didn't happen for another month or so until I had a morning off work with the kids at daycare. A week or so prior, I pulled out the MDF sheets I had and did a quick thickness test, and a rough cut with the circular saw to make the rest of the cuts more manageable on the table saw. Conditions hadn't improved much by the time I got to the rest of the cutting. I had less snow, but a lot of fog and periodic misty periods. I rigged up a little support system for the first cut on the larger panels, and got to making dust.

Setting up the saw and running all the same length cuts one after another makes things SO much easier. Then even if I make a mistake, at least I'm consistent and things will match up. By the end of the morning I had 2 nice piles of panels ready to go. I decided to make the inner baffle out of 3/4" plywood, to give the T-nuts something a little tougher to bite into with this heavy driver. The final subs should be about 20 x 22, which seems tiny when I look at them now, but I have no doubts they'll get the job done.
 

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#8 · (Edited)
The driver is bigger than your helper! :clap:

Excellent build thread.
Coming along nicely! Looks like you could use an outflow table. You have some nice tools. It would make life a lot easier. Looking forward to the build!
Wowzers that's going to be one monster sub setup! Looks great :grin2:
Thanks everyone! I'm REALLY looking forward to getting these up and running.

That is very small for that size sub woofer!..Is that the recommended size cabinet?
It's on the small side, but this driver does well in small sealed enclosures. 3.5 - 4 cubes is great, but in all my sims it was barely noticeable to go down to 3.3, and that fit the size I was hoping for. They'll be tucked behind a screen wall eventually, so I wanted to keep the depth under 2', with enough wiggle room to move them around. Also, the smaller airspace will give me a bit more protection from accidental overexcursion.

Oh, and yeah Tonto, I really could use a nice outfeed table setup. This was the best I could cobble together on short notice, but it actually worked really well. There are so many tools and accessories that I would LIKE to have, but I just can't justify for practical reasons. My tools aren't super fancy or anything, but they do the job.

That table saw was rescued from the dump by my dad and rehabilitated for me. I like the old SOLID saws vs the newer contractor ones, because having a big rigid surface is a big help sometimes. He put it on wheels for me, and I built my garage bench with a little parking spot for it underneath, so I can still fit the car in when it's put away. A table saw was one tool I wasn't willing to go without, even with my limited space. ;)
 
#12 ·
Yeah Tonto, that's good advice. I always cut this stuff outside, and make sure my helpers are in the house when the dust is flying.

Still making progress when I get some time. I got to work on the baffles this weekend, and feel pretty good about the outcome. Maybe not 100% good... but at least 90%.

The first thing I did was clamp the 2 baffles together, use scrap MDF to make sure they were centered and wouldn't leave me with overhang, and then mark the centre on the smaller inner baffle. Then I drilled out a pinhole to use as a pivot for my router jig.



My jig is just a simple piece of smoked 1/4" plexiglass that I used way back on my original Tempest build, and have somehow managed not to lose, despite moving since then. We drilled and countersunk for the 3 mounting points on the router, and cut a hole in the middle. Then I just measure and drill the pivot holes as needed. In this case I think I went with 8 3/8" for the inner baffle, and 9 1/4" for the outer baffle. I set up a piece of 1/2" foam board to test with, since I haven't done this in about a decade.



I did notice some wobble, since the foam can't really hold the pin nail perfectly still, but I figured this was as much a conceptual effort as it was practical, and I just tried not to wiggle it too much. The inner baffle test piece seemed to go well.





The wobbles are evident, but the process went fairly smoothly, so I used that hole to continue on to the plywood inner baffle. That cut well, and was a pretty good fit. I probably could have gone about 1/64" smaller, but I'd say that's about as good as I can ask for without CNC help.



I cut out both baffles, and somehow had some variance, but they're both good to go.



Next I set up for the outer baffle, and again did a test on some foam board. Actually I wasn't 100% happy with the first cutout, so I did a second foam test, to try to keep the cutout a little tighter. I figured "I can always take more off, but I can't put it back on". So the foam baffle was just about perfect, and I moved on to cut the MDF.



Here's where the wobble came back to bite me. The cut looks good, but it's basically snug to the thick rubber gasket, and I can press fit the baffle holding itself up in place without any support. In this case I could have taken an extra 1/64" off, which would have been about perfect. Somehow I didn't take a pic of it in place, but here's my helper holding up the baffle.



Now I have to figure out how to shave sown the inside of the cutout a little bit. I already went at it by hand with some 80 grit, which took care of any little imperfections, but didn't make much difference in the overall fit. Is there an easy way to take a bit of material off? I don't want to buy any of those fancy sanding drum barrels, but I might be able to rig something up to chuck into the drill. I don't think either of my palm sanders will make much contact with the surface on this arc.

The other option is taking off that massive rubber gasket and just using some foam weather stripping tape or something around the inner baffle. Any thoughts on these gaskets? Are they recommended to use, or will something more generic work just as well?

The next thing I was blissfully unaware of is how tight my overall fit is, regarding the actual dimensions of the sub. I had planned for 20" width and 22" height. The width got reduced by about 1/8" during my panel cutting thanks to a sloppy cut (so I shaved down all the panels to match). When I fit the 2 baffles together, it's clear there's a gap at the sides.



The gap is small, actually a bit smaller than in the pic above, and it will be covered by where the side panels fit in, I just have to make sure there's room for T-nuts. I'll probably offset the mounting to account for that and hope it will be enough.

And that's about as far as I got over the weekend. Now I just need to decide if it would be better to trim down the inside of the outer baffles a bit or to remove the rubber gaskets from the drivers. Then I can figure out an assembly order and start gluing panels.

NOTE: I tried using the gallery and directly inserting images into this post, instead of attaching them at the bottom. I always feel that it's better to see pics in order as the "story" unfolds, but it is definitely a bit slower this way. The gallery is better than other forums, but still a bit clunky. I don't want to come back to this thread in 5 years and have all the images missing, which is the case with a lot of my old threads, so I'm avoiding external hosting. I might just go back to attaching next time, we'll see.
 
#15 ·
The cartridge rolls are much smaller and less expensive than the attachments in your link, so it might be worth considering if you can't rig up something. You can probably find them at Lowes/Home Depot kind of places.
 
#22 ·
Looks like the neighbors will get to enjoy the power of the new subs also. [emoji2]
I ran into my neighbour when I was out cutting the baffles, and I told him I'd try to keep it down when they get set up. Lol.

I'm actually very curious to see how much sound will escape the basement and the house when all is said and done. Our house is detached, but the neighbour is about 5' away.

Sent from my LG-H812 using Tapatalk
 
#25 ·
Deep bass sound waves can travel great distances, but it's not a linear spread of sound..
Your neighbour 5' away may not feel or hear anything, but the guy three doors down the road might have his teeth rattling or his eardrums bouncing!
There's no guarantee of who will be affected by it..
 
#27 ·
We'll just have to see who the unlucky neighbour is in this case, I guess! :rofl:

Owen, it's easy to get the center. Cut some small spacers to fill the gap created by the original cut. When you clamp it, it will be dead center. Just tap a nail through the cut out into the backer board. Clamp it together before nailing of course! You should be able to shave off the right amount. Don't worry about the spacers, just cut right through them. How much do you need to trim?
Thanks Tonto, I had a few minutes to myself last night, and I took a look at doing it this way. I think I can make it work, but the baffle is small enough that I can't fit clamps on the corners and get the router around. I do have a solution, I think.

I mocked up a board with the circular cutout on it, and played with spacing. Once I thought it was feasible, I centered the cutout and screwed it into the board, and put a couple of clamps on each end. Here's where it's going to get tricky... Since I'll have to remove the clamps as I go around those corners, I'm going to try to tape the board in place as a secondary method of securing it. If that won't hold without some wiggle until I can get the clamps back on, then I'll just have to screw into the backside of the baffle. I still have to measure my distance and add a new pivot hole to my template. I should get this all done over the weekend, and I'll post some pics on Monday.
 
#26 ·
Owen, it's easy to get the center. Cut some small spacers to fill the gap created by the original cut. When you clamp it, it will be dead center. Just tap a nail through the cut out into the backer board. Clamp it together before nailing of course! You should be able to shave off the right amount. Don't worry about the spacers, just cut right through them. How much do you need to trim?
 
#28 ·
I'm still alive, and so is this project. It's been a few weeks of intermittent activity due to flippin' COLD weather and kid stuff, but I've slowly chipped away at things to the point where I feel like I can post again.

I managed to slightly enlarge the woofer cutouts successfully by reinserting the previous plug, screwed to a long board that I clamped into position on the baffle (thanks, @Tonto!). This, after very careful measuring, gave me my exact centre again, and let me use the router jig to go around and take an incremental amount off the inside. It worked very well, actually. To save time and trouble, I picked up a flush trim bit and used it to copy the cutout to the second baffle. It was my first time using one and I was quite impressed.





Once I was happy with the fit of both the inner and outer baffles, I glued them together and used the stack of unbuilt enclosure panels to weigh them down because I thought this would be more uniform pressure than I'd get with clamps.





Next I mocked up a test fit of the first enclosure to check my cuts, confirm assembly order, and to measure for some bracing. I had some vague plans for bracing, but when I saw the actual dimensions I have to work with I scrapped them and just made some on-the-fly decisions. The sides will have 3 cross braces, top to bottom will have 2, and the piece that is in place in the picture below is how the rear panel ties in to one of the 3 lateral cross pieces. I think this should do the trick when I get it all set up. I didn't have zipties handy, so I made some handles for the woofer out of twine. I also decided to bail out on the T-nuts and threaded inserts, and to stick with screws, so I started gluing blocks on to the back of the inner baffle to give some more depth to bite into.







I went to see if HD carried any nice looking black cap head screws, which they didn't. I did see these though, which look interesting, assuming the integrated washer head is the right size for the woofer basket. If I go with these I might shoot them with a bit of black paint before sinking them. Any thoughts?

 

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#31 ·
"When it rains it pours", I guess. I had some more time to put in work on the first cabinet, and glued up a second side (the top, in addition to a side, actually) as well as the remaining two "side to side" braces (sitting vertically now for glue-up. The side panel that is on top is just resting there to keep the 2 braces stable and square while they are glued at the "bottom" only. If I can continue to get a little in over the next few days I should be able to finish the first one by the weekend. But now that I just went and said that, and stated a date, guess what's going to happen...? :rolleyes: LOL
 

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#36 · (Edited)
And I now feel like I've accomplished something. Enclosure 1 is assembled, and came out not too badly. There were definitely mistakes made, but nothing too critical. The first half of the enclosure came together REALLY nicely and I was astonished at how tight my edges and corners were joining up. I squared up and glued in my last braces, and was pretty happy with how they worked out.



The first noticeable mistake came when I was test fitting the final panels, and - oops! - I had measured and cut the braces for an inset panel instead of a panel that would be attached to the outside of the adjoining walls. No big deal, I was off by exactly a panel width, so I added some spacers to the braces. You can see the blocks up on top. Now it's a nice tight fit.



My next mistake was the order I chose to assemble. Basically at this point I was left with 2 side panels and the baffle to go together in one step (because of the stepped baffle I couldn't slide it in very well if 3 sides were closed in). I thought I could manage it not too badly with the 7 long clamps I had, but I really should have had 3 more. I made due, and got strategic about where clamps went, and then I used weight on the baffle when I ran out. I could have used a couple more to help pull a few corners into square a touch better, but it came out OK.



The final result from this morning's unclamping. It's not the prettiest, but it's solid. It will need a good amount of filling and sanding before I can think about finishing it, but at least I do feel like I got a good seal. Almost all of the interior corners had a fair bit of squeezeout, which I was able to run a finger over to complete most edges. I'll probably run a quick bead of something over a few of the final joints internally just to be safe.



And now I get to do it all over again! With the next one I'm going to start with the baffle, and work my way around a side or 2 at a time. That should help me to keep things tight, and not leave me gluing in 3 dimensions at a time. I'll probably just post the final when the next one is completed, since it will be more of the same.
 

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#37 · (Edited)
For some reason I can't open the 4th page of this thread on my computer no matter what I try, so I can't edit that post to insert the pics. It's been that way for the last couple days on my work computer. I'll try from home tonight. Anyone else having trouble?

Sent from my LG-H812 using Tapatalk

Nevermind, all good now.
 
#38 ·
For some reason I can't open the 4th page of this thread on my computer no matter what I try, so I can't edit that post to insert the pics. It's been that way for the last couple days on my work computer. I'll try from home tonight. Anyone else having trouble?

Sent from my LG-H812 using Tapatalk
Tapatalk is most likely the culprit. Seems people have a lot of problems with that. On a laptop I can open any page of your thread.
 
#40 ·
OK, I've been shamefully neglectful of both this project and this thread, but I have made some progress since my last posts. The big holdup was that I was waiting for my new flush trim bit to come from China. It's a $6.00 Amazon special, and as you can see, it really is "trump card quality". But more to the point, it worked, and as far as I'm concerned it worked pretty well. I had a few wiggles, but overall didn't make too big of a mess with it.





Next I moved on to filling. I wanted to try something other than the Dap drywall compound I had used before, so I picked up a small tub of Elmer's ProBond Max wood filler. I think it would be nice when working with large areas or gaps, but since it seems to be textured, it isn't great for the tiny gaps I had here. I made it work, and there was only one area that needed buildup. At least it sands well.





Next, I wanted to get moving with the details on the enclosures. I had planned to do a large chamfer around the top of each box. When the time came to get to work, the chamfer bit I had wasn't very big, but I figured I could always get a bigger one and go over it later if I wanted. I ended up liking the profile as-is, so things were going great... until I realized that I had just done the SIDES of the enclosures instead of the TOPS. I had them with sides up after sanding, and hadn't remembered to check the orientation I was so gung-ho to start using the router. D'OH! Well, it just meant that now all corners would be subject to the chamfer treatment. Not the end of the world. My helper for the afternoon seemed to think they were still a good home for his dinos.





 

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#41 ·
Next up I had to drill the mounting holes for the Speakon connectors. I decided to use 2 connectors per enclosure, because the speakon protrudes quite a bit when plugged in, and I don't know what orientation I'm going to end up with in the final position, or how close to a wall they might be. This way I should have some flexibility. I measured for hole size, and since I didn't have a proper forstner bit in the size I needed, so I went to my cheap hole saw kit.









The test worked out almost perfectly. First, I used the large hole saw to cut a groove about as deep as the thickness of the plate on the Neutrik plugs I'm using. Then I used the small one to cut the through hole that the body of the plug sits in. Then I used a small chisel to remove the extra material "ring" to allow the plug to sit flush. The process worked really well, and the fit was almost perfectly snug. You just have to be gentle with the chisel, because the MDF "layers" don't need much pressure to lift and peel.







These hole saws are probably meant for drywall, and were dull before I started, but they eventually got the job done after taking lots of breaks to clean out the teeth and the plugs that would get stuck inside. In the end, I had 2 nice mounting holes in each enclosure. And you can bet I checked the orientation of the enclosures about 3 times before I started drilling.





Now I think I'm ready to prime, and then start painting. I'm going to use the same 'flat' paint I used on the HTM-12's, but this time I'm going to dump in some black that I have lying around. The colour by itself on the HTM's is a little greener than I'd like. We'll see how that goes.
 

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#42 ·
Progress continues! Small steps, but it's all I could manage with some sick little guys at home this weekend. One coat of primer on to seal. I need to do some sanding in a few places, and might do a second coat of primer, but I'll probably just go on to 2 coats of paint. Next update should be all painted, with terminals mounted. Maybe even drivers. Anyone have a go-to material for securing and making the terminals airtight? I'd use PL, but I don't want to open a tube just to deal with 4 little terminals. Needs to bond well to MDF and plastic.
 

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#43 ·
Connector sealing:

For my 12" sub pair build, I used foam medium density adhesive backed weatherstripping (from Lowe's) cut in a circle and stuck onto the backside of the SpeakOn jack. I've also used a window caulking in some builds and Fiberglas in other builds.

Filling irregularities:

I've never thought to use drywall compound; seems too lightweight. Wood filler would be better. I like body filler for cosmetic leveling as it sands super well for creating invisible blend lines which, if you're painting, will be very much appreciated (I like Evercoat Rage Gold). For sealing any panel gaps, I like any 'ol Fiberglas resin on the inside of the enclosure and the body filler on the outside.

Screws:

Short story: I have a pair of Sundown 6.5" subs in my M3 and they came with a very thick rubber gasket. I took it off because I needed them to sit flush in the enclosure, but in doing so it revealed that the surround is glued all the way to the edge of the frame. Had I used that screw/washer combination, I felt the combo would have spun the rubber bond loose as it got close to tightening down and would damage the bond of the surround to the frame. I used a screw which had head diameter the same as the shaft which made contact with only the frame and not the rubber (two examples are below). Point is: make sure you can secure drivers down without damage with those screws you've chosen. I don't want to see a post about damaging those really nice drivers!

I'm curious to see the paint finish once it's done. What type of paint are you using and how are you applying it? I like your bracing too.... much more than my last one, but I've not built an enclosure for 18's yet!
 

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#44 ·
A quick pre-update that I thought I had already posted. I decided I definitely wanted to have options for where to plug the speakon connectors in, and options for how to orient the sub in place (facing out, facing back, sideways, whatever). To make this a little more feasible, I decided to install a pair of jacks on each sub. It was a relatively simple job to wire up the internal connection, and shouldn't have any downside, so I'm glad I did it this way.
 

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