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Discussion Starter · #1 · (Edited)
Dual UXL 18 Sealed Plans & Build

** Note: actual build starts at post 42 **

It looks like I was able to just squeak in to the group buy for a pair of UXL 18s, and I jumped on it before I had a chance to do much research or planning. I took enough time to assure myself that the price was right, and that they were still solid performers, and the local Canadian source (no need to re-ship/drive to border/etc.) was what sealed the deal for me.

I had been planning for a long time to use a pair of sealed 18s in our theatre build, so there’s no deviation there. I was considering the SI HT18 before they disappeared, and then looking at either the new DS4-18 or possibly an Ultimax 18, both a step up with a corresponding increase in price. When I saw the chance for a pair of UXLs, I did some quick googling and determined that they seem to have more output capability than the other 2 (at least a higher Vd), were well regarded, and perform well in small sealed enclosures. That’s another plus for me, because I wanted to keep mine under 2x2x2 to hide behind a tight screen wall. Price will be reasonably comparable by the time I get them all to my door, though they are still likely a little more than the SI or Daytons would have been.

Now... what to do with them!? As I said, I had been planning for a pair of sealed 18s. Right now I’m running a large ported (original) Tempest tuned to 19Hz, and a ported SDX10 tuned around 25Hz. By my calculations, those two combined still fall well short of the Vd of a single UXL, so I think I’ll be in for a noticeable upgrade. I’ve been very interested in trying a Linkwitz Transform design for a long time, and I think that’s the route I’d like to take with these. I like the idea of a small sealed sub with a very capable driver given a good amount of power and EQ to achieve optimal results. My planned amp so far is an inuke 6000DSP based on the performance per dollar ratio. I get the impression that the UXL is a hungry beast, and I want to make sure they have enough power to really get moving. With that said, my room is less than 10x20x8 (1,600 cubic feet) so I don’t anticipate the need to drive them very hard to get enough output.

So, where do I start? It seems that the UXL likes small sealed enclosures, so let’s start with about 3.5 cubes, which seems common. A 20x20x22 enclosure made from 3/4" material with a double front baffle, less about 1/3 cu ft for the driver gives me 3.566 cubes (internal). Minimal bracing won’t hurt that too much, and stuffing will help to offset.

If I’m modeling that correctly in WinISD, that gives me an f3 of 46Hz, and an f6 of 32 Hz. Now I’ll need to improve on that. If I wanted to do it quick and simple, I could use the DSP from the inuke6000 and dial in a few bumps. Alternatively, I still have my BFD (Behringer DSP1124P) that I could use for simple EQ and not need the DSP model inuke. OR... if it actually provides a better solution, I’d be happy to skip the DSP model and pick up a MiniDSP, which I could program with the Linkwitz Transform tool and do it properly. I have a few problems here.

First, I don’t really have a specific target frequency, I just want to maximize my useable low end response. Second, I’ve been playing with the LT in WinISD and it seems to take the cone excursion beyond Xmax pretty quickly with well under the 3,000W theoretically on tap (as expected, really). Building in a 10Hz high pass seems to help, but I really don’t know how to properly model this and integrate real world amplifier power.

I guess that’s where I am right now. Maybe not as completely lost as I thought, but in need of some serious mentoring to make what will be my last (?) sub build as epic as it can be.
 

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6k @4ohms will be more like 11-1200wpc according to bench tests, I think brief periods or only 1 channel will do ~1800w. Maybe I'm mistaken.

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Here is a bench test of the 6k so you get a better idea of what you can expect, pay attention to the test duration and the frequency tested, low frequency is more taxing as you'll see.
notnyt from here also has an amplifier test thread with the NU46000 I believe, he's tested 2 berries I THINK.
Take a look at this thread for the 6k, pay attention to duty cycle and both channels vs 1.
http://forum.speakerplans.com/behringer-inuke-nu6000-vs-kam-kxd7200-bench-tested_topic69202.html

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Probably just set the limiter for voltage peaks and be done with it.
Folks tend to set a limiter on the Berries just to keep it under control/ not shut down, even if the driver can handle it.
I figure just a bit below max.
It even mentions that in that thread I linked I THINK.
Good Luck, glad to help!

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We'll see... I know just enough to make a complicated mess of things.

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Lol...
You're in good hands here bud.. There should be enough guys local to you if you need any hands on help too.
 

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I'll be keeping an eye on this thread.. I am another Canadian doing a dual UXL build soon! I'm doing the full martys :). I'm pretty bad with electrical/the theory behind everything too so I'm hoping when I hook everything up I don't blow up the NU6000 with the wrong settings..
 

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Discussion Starter · #13 ·
I'll do what I can to clear the waters for you, systemlayers!

uniquepattern, careful, you're tempting me to drive up your way to audition your 24" monsters!

OK, I've been at it again. I like the idea of designing everything, including the LT in WinISD, because it lets me see the effects of my EQ, rather than just adding +6dB of boost at 20Hz after I get it in-room and wondering why it went CLANK. I know I'll still need some tweaking after setup, but my plan is to maximize low extension within safe Xmax limits, and then if I have to EQ in-room I can stick to making cuts to flatten my response.

Here are 2 graphs from my experimenting. Sealed enclosure (3.566 ft^3), Single UXL-18, using 1,200W input power. Yellow is the original model, and blue adds the LT filter specified. At this point the LT was just a result of playing with numbers, there was no hard reason behind what I used.

Clearly I need to work on the excursion in the LT model, and I'll try out a high pass at 10Hz or so, but is this generally how people manage the details? Just trial and error? I really like muzz's point about a voltage limiter, and I need to do more reading about them.
 

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A 30A breaker will be needed to get 1200watts RMS x2 without tripping it. (Assuming the amplifier is legit.)
A 30A breaker would support roughly ~1500watts RMS x2. A 20A breaker is 33% less power, and a 15A breaker is 50% less power.

That's just the laws of physics talking.

Burst power is usually
 

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Discussion Starter · #16 · (Edited)
A 30A breaker will be needed to get 1200watts RMS x2 without tripping it. (Assuming the amplifier is legit.)
A 30A breaker would support roughly ~1500watts RMS x2. A 20A breaker is 33% less power, and a 15A breaker is 50% less power.

That's just the laws of physics talking.

Burst power is usually
 

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Discussion Starter · #19 ·
I've been doing more reading, and it seems like there are a lot of people successfully running quite a lot of gear (including multiple amps/AVRs) off even a single 15A circuit, so I think I'll be in good shape with a 20A just for the inuke, and a dedicated 15A for the rest of the gear. Volume seems to be the key factor in power consumption, and this room is going to be tiny, so I can't see us cranking things up to ear splitting levels. At least not on a regular basis.
 

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I think you'll be good. I was tripping the 20amp breaker just before clipping on a CV-5000, which is why I put in the 30amp circuit. You shouldn't have that problem with the iNuke.


Edit for clarification...I was running the CV-5000(old school iron) at 2ohm stereo
 
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