OJ's Dual UXL-18 Sealed Build

[Sonnie Parker]

I hope they do too... I have a few thousand in the cabin we are building by our pond.

 

[OJ Bartley]

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 REW 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.

 

[Prof.]

They look cool Owen..

 

[Sonnie Parker]

That's some serious subwoofage there Owen. I look forward to seeing some measurements.

I don't see your miniDSP listed in your equipment listing... what model do you have?

 

[Peter Loeser]

Very nicely done! Great looking subs, no doubt they'll sound incredible.

 

[OJ Bartley]

They look cool Owen..

Very nicely done! Great looking subs, no doubt they'll sound incredible.

That's some serious subwoofage there Owen. I look forward to seeing some measurements.

I don't see your miniDSP listed in your equipment listing... what model do you have?

Thanks guys! I am excited to have a pair of some REAL big boy subs (although I'm sure I'd get some minor arguments from the ported guys) that are definitely top tier equipment.

Sonnie, I recently took delivery of a balanced 2x4, which is still in the box. Actually, I'll have to update my profile to include the iNuke and UXLs now, won't I? I'll add the MiniDSP once I get it added to the signal chain.

 

[Sonnie Parker]

Gotcha... yeah... that will be a nice addition no doubt.

 

[theJman]

View attachment 2133

Your subwoofers dwarf a set of tower speakers? That's what I call having your priorities right; bass first!

 

[tesseract]

Actually, I'll have to update my profile to include the iNuke and UXLs now, won't I? I'll add the MiniDSP once I get it added to the signal chain.

The miniDSP will add precision bass management, indeed. Are you using a DSP iNuke for a Linkwitz Transform?

 

[Manic1]

Yep, @Sonnie for the win with GRK. I had a reference to them in my older "extended" thread but I guess it didn't make the redux version. I was very happy with these. Hopefully they'll hold nice and strong for a long time.
View attachment 2120

Great Job! I managed to pick up a UM-18 driver last weekend. Seems like PE has been out for a while. Do not have your skills so a flat pack is in my future. Say, I have 2 subs and am going to add another. How do you connect the nu6000 to a pre-pro to take advantage of XT32? Do I need a 2x4 DSP?

 

[OJ Bartley]

The miniDSP will add precision bass management, indeed. Are you using a DSP iNuke for a Linkwitz Transform?

Dennis, I'm uh... a bit late replying to this, I never saw the notice. I'm using the plain vanilla non-DSP iNuke, but I have thought about building some kind of LT with the MiniDSP. I haven't done that yet, though I did get it all set up, and I used the filters from REW to tweak it a little. It definitely sounds better with the MiniDSP in the chain. I was able to decrease the levels in the AVR and turn the amp gain down a bit to achieve the same volume with the Mini plugged in, and the bass definitely has an improved quality as well.

I will probably try something like a proper LT when I eventually get the theatre built, which is some time down the road. I want to see how these measure in a small enclosed room and then I'll figure out what to do with them.

Great Job! I managed to pick up a UM-18 driver last weekend. Seems like PE has been out for a while. Do not have your skills so a flat pack is in my future. Say, I have 2 subs and am going to add another. How do you connect the nu6000 to a pre-pro to take advantage of XT32? Do I need a 2x4 DSP?

Manic, same as above, I'm sorry I'm just getting to this! Congratulations on the Ultimax pickup, they have been in great demand lately. I bet you'll be very happy with your addition once you get it up and running. Let's see... in brief, the answer to your questions sort of depend on how you're set up right now. The simplest way to add an iNuke and new sub to what you have is to use an RCA splitter to get an extra output from your AVR's LFE/Sub out. Then you'll need either an RCA to XLR or an RCA to 1/4" plug cable or adapter. I started out with the latter, which worked OK, and now have moved to using XLRs from the MiniDSP. This will allow your AVR to have some control over the levels by using Audyssey. But keep in mind it will probably only want to reduce the levels (significantly) with 3 subs in the room. Try it and see how it sounds, especially after you get the levels turned back up to where they should be after XT32 does its thing. If you feel like you are missing something, adding a MiniDSP will give you a lot more control, including 2 inputs and up to 4 outputs, each one adjustable with custom EQ and delay settings.

 

[OJ Bartley]

As mentioned above, I have now got the MiniDSP up and running, and I was able to use REW to generate the filters to import into the MiniDSP. I made one custom addition to boost a null, and things are sounding pretty great.

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.

 

[muzz]

How'd you make out integrating the subs? is that tempest cab a ported sub?

 

[OJ Bartley]

How'd you make out integrating the subs? is that tempest cab a ported sub?

Muzz, I'm poking at it a little here and there. I tweaked my EQ settings in REW a couple of weeks ago and uploaded the new set to the MiniDSP, and I think I made a small improvement. Just over the weekend I was playing with the graphs in the EQ again, and I think I have a new revision I'd like to try, with a more aggressive house curve. I haven't uploaded it to the Mini yet, but maybe I'll get a chance this week.

The Tempest is ported, yes. I think it's tuned to around 19Hz. I really can't say enough about it, it still holds its own after over 10 years, with a measly 150w amp. One big difference when I have the UXLs on though is the presence of the really low content is felt, rather than heard. Even at low volumes, it adds a lot to the experience. I can't wait till they're a little more dialed in, and I can put them through their paces with a full movie again.

 

[muzz]

I've read integrating sealed and ported can be difficult, I think it had to do with phase, but not sure about that.
Good Luck!