Owen's Dual UXL-18 Sealed Build

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.

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.

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!

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.

...And we have arrived at the final chapter at last. Over the weekend I wanted to make a push to complete these subs, because enough is enough. Projects can drag on, but I really needed to get this one wrapped up. To force myself to get things done, I brought the driver and enclosure in and parked them on the dining room table. Please ignore the circus sideshow that our house has become with 2 boys and all their toys and no basement yet. Sorry, some of these pics are pretty bad, apparently my phone doesn't do well in low light.

My strategy worked pretty well, and I got the sub put together at naptime on Saturday. I forgot to weigh the completed enclosure with the driver in it, but I'm definitely glad I didn't have to move it very far. The screws I picked worked really well. I just lifted up the edge of the gasket, placed the screw and sunk it, and when the gasket goes back into place it's virtually invisible. The integrated washer gives me some more confidence about its holding ability.

So, fully assembled and upright, I'm pretty happy with the final product, although I do still wish I hadn't messed up my initial design plan for the chamfers. The Neutrik jacks flush mounted pretty nicely, and I'm glad I'll have some flexibility regarding plug placement because those things really do stick out when connected.

Here's the first completed sub next to the SDX-10 it will be temporarily replacing. The enclosure really isn't THAT much bigger on the whole. The SDX is still a great little sub, and will probably come back to living room duty when the basement gets finished.

And set up in place (for now) it really doesn't look that big, especially compared to the Tempest that's twice its size on the other side. I'm going to stack the pair of them for now, and probably still run the Tempest too, unless it really messes things up.

I didn't get to do a lot of testing, but I played around a bit with Bass I Love you, which sounded good, and Curtain Shaker, which to be honest I saw a lot of cone movement but didn't hear much. I threw in some kid friendly demo material with the Titan A.E. Ice Field scene, and was able to do a little bit of playing with the sub level and iNuke knob. I ended up with the level about 6 or 8dB hot, and still have the iNuke gain at about 2:00, which gave me the best balance between audible hum and strong output.

Now, I'm splitting the single LFE output from the Denon 3 ways (one to the iNuke, one to the Tempest, and one to the Buttkicker amp) so I assume this results in some reduction of signal strength. I haven't re-run Audyssey or changed anything other than the sub level. I know I have a lot left on the table, between doing some gain matching, adding the MiniDSP, and taking some measurements and adding filters. I really don't have an impression of it yet, I just haven't spent enough time with it.

In the limited time I've had, I like it so far. The output is there, although it seems like I have to drive it pretty hard to achieve it. It seems to be quite articulate, and blends well when it isn't pumping out explosions. We managed to find ehough time for a movie last night and put in Jack Reacher 2. It's an action movie, but not one I'd say with a great deal of low end material. It did have a few moments, which the sub handled well, but it also did a very good job of not calling attention to itself while filling in the more subtle stuff. More testing is definitely required, and when I have the pair up and running, I'll tackle the MiniDSP for better integration. I'm very much looking forward to that, especially to see if I can bring down the gain on the iNuke and reduce the hum that comes in strong after about 2:00 on the dial.

Oh, and speaking of the iNuke, I was expecting much worse fan noise. I have a recent model and although it was noticeable, it wasn't as obnoxious as I anticipated. In the final install I'll work out some kind of hushbox of sorts to cut that down, but it will be fine in the short run.

I feel like a weight has been lifted from my shoulders. Or, more precicely, a pair of 94.6 lb weights. Sub #2 is done and in its temporary home.

I haven't had time to do any real testing, because it wasn't in place until well after the kids were asleep, but I tried out a few demo scenes just "to make sure everything was working". A couple of scenes from the AVS bass demo disc confirmed that, and Deadpool and The Force Awakens showed me that the second one did make a noticeable difference. Right now the best part about that is that I can dial the gain back down some and get the same output with less hum. I also did another runthrough of Curtain Shaker, and I still struggled to hear anything... until I noticed the screen door at the front of the house buzzing and rattling. Considering our entire house is basically 2 floors of open layout, that made me happy.

I hope to get started with REQ and the MiniDSP over the next month or so, and I'll do some more critical listening then, but for now I'm good. So far I've been very impressed with these UXLs, and I have a strong feeling they're only going to get better.

Since completion, I have finally hooked up the MiniDSP and run some filters with the help of REW. There was a definite improvement in the overall output level of the subs and the qualitative sound as well.

One thing, however, that I did still need to fix was the fan noise from the iNuke amp. It was enough that we generally didn't turn the new subs on for general watching, and unless we were putting on a blockbuster type movie. Even then, the fans were audible and annoying during quiet passages.

So after reading up on a lot of different people's approaches, I settled on just replacing the two 80mm fans with Noctua fans, which were said to be near silent, and most people had no issues with heat after the swap. I had considered using 92mm or 120mm fans with an adapter to get more air flow at less RPMs, but in the end decided to just go for the simplest option that was largely a proven success.

Here's how we start. I used two Noctua NF-A8 (FLX) fans, which were about $20 each from Amazon.ca. Yes, that's expensive for an 80mm fan, but Noctua's reputation for both quality and quietness is about the best there is, so I figured they were worth it. When the fans arrived, the packaging and included accessories was very impressive, and the fans are very well designed and made, unlike a $5.00 PC store special.



The first step is to remove the top of the amp case, which is done by removing six small Phillips screws. The fans also have obvious screws on the back of the amp, which also hold the grilles on (also Phillips). I have indicated where the fan headers attach to the board in this pic.



The header plugs have a dab of glue on them to hold them in place, but that wasn't too hard to pick off and loosen up enough to remove the plugs. The biggest hurdle I encountered here was the big blob of glue that was used to secure the fan wires to the bottom of the amp chassis. Oh, and of course the wires were twisted and crossed in the pile of glue, so removing them took a while. I tried to pick and pull them out, but it just wasn't working, so I heated up the glue gun and used the tip as a prod to loosen the wires and separate them. Once that was done, the rest was smooth sailing.



I replaced the two fans, which were a perfect fit, and the relatively short lead wires were just enough to run to the fan connectors on the board (circled). If I needed more length, the Noctuas came with an extension plug that would have worked fine.



I did what I could to keep the wires out of the way, and plugged them in to the board for a quick power test. Make sure you have + to + and - to - first, with the yellow PWM wire overhanging and remaining disconnected. Everything worked, so I unplugged the amp and got ready to close up. I decided that since the lead wires were JUST enough to get to the connectors, and the pins from the board were a little shorter than the plugs ideally would have taken, I wanted to make sure they stayed in place so I took a page from the manufacturer and added a little blob of hot glue to secure the two in place.





With the top back in place, I fired up the amp for another test, and had no problems. A few things of note to me after the swap:

- The fans really are a night and day difference. The Noctuas are near silent from about 2' away, and when I got the amp back in place, the hum of the LED ceiling bulb was louder than the amp.
- I am a little concerned about the volume of air being moved though. That was also a big change, and I can barely feel much air at all coming out the front of the amp when it is on anymore.
- Since many people have used these fans without problems, I'm not going to worry much, but it was definitely a significant decrease in air flow. I'd be OK with a little more noise and a little more air movement, but if this works well then it really is ideal.
- I have considered drilling out a few holes in the front of the amp faceplate, since the existing vents aren't exactly optimized for good flow. We'll see how things go.

I left the amp idling for 30 mins or so and didn't notice any issues. I only had time to run one quiet passage to test with any kind of load, and it worked fine as well. I guess time will tell, and how hard I'm driving the UXLs will be the biggest factor in the long run, but overall my first impression is that this was a success. Thanks to all who helped out with information and by posting their own procedure and results.

Oh, and just a note... I've read others say that they believe their fans may ramp up speed as heat (or load?) is detected in the amp, but I certainly haven't noticed this, and I don't know if this is even possible with the connections on the board. I guess it may be able to vary the voltage to the headers, but that seems advanced for this type of no-feature amp. I might be wrong, but that's my impression so far.