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Discussion Starter · #1 ·
So after several months of planning...and waiting, I've finally started building the the box for a UXL-18 in a 7.6 cubic foot box tuned to 15hz.


The plan:
Dimensions:

The exterior dimensions are 25h x 25w x 30d made of 3/4 MDF with plywood for the speaker mount.

Ports

It will use four 3" diameter x 44" long ports, made from 3" pvc, with precision port internal and external flare. I'm planning on securing them with loop clamps

Design:




Dimensions of the various pieces:


Front



Baffle:



Mount Ring (this will be plywood and contain the threaded inserts)



Back:



Sides:



Top/Bottom



Bracing:



The cutlist for everything. It requires 2 sheets of mdf (at 49x97 dimensions). This contains some extra items I don't necessarily need (the port grill covers, horizontal bracing, and full front cutouts)




Cutlist for the ports


*You need to add 1-7/16 inches to the 19" and 4 inch piece to account for the space in the elbow

**The piece between the two elbows needs to be 2.5 inches



WinISD Results




This is without a highpass filter, which it looks like I'll need. With it on this drops to around 20m/s



Originally I was saving each design in a separate file but towards the end I would just move things around. I ended up with a fairly impressive design graveyard hah



Power:

I'm planning on using an EP4000 amp. I would love to get a QSC RMX1450 but it's a good 200 bucks more expensive and the only real bad thing I've heard about the ep4000 is it's a copy of the RMX1450 and the fan is loud (which seems pretty easy to fix).

Veneer

I'm going to veneer it with some 10 mil white ash. I was planning on doing 3/4" rounded edges on the top and bottom sides but veneering would be so much easier if I didn't.

Finish

Either way, I'm going to be painting it black lacquer (trying to get the typical black ash finish). I'm going to build a small paint booth but I wasn't planning on using any fans and just going with a suit and respirator but should I look into exhausts? I didn't think it would be necessary for something this small

Applcation will be via the heat glue method, coating the box and veneer and using a clothing iron to heat the glue and trimming with a flush trim router.

Starting with a light 240 grit sanding before painting

Everything will be diluted with 10-15% thinner

two light coats of black #40 sheen lacquer primer sprayed with a HVLP gun.

two light coats of #40 sheen, semi-gloss black

single coat of #40 sheen clear (maybe 2 depending on how much grain I want to see)

Feet

Nothing fancy, I'm gonna go with 4 of the dayton audio 1-3/8 hard rubber feet. I haven't quote decided where to put them, or if I should use more than 4 yet


**I'm going to be using ez-lock nuts + bolts for everything so that the speaker, terminal and feet are removable
 

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Discussion Starter · #2 ·
Here are the first pics after it arrived. I basically took a long lunch from work, got home, unboxed it, took a pic and ran back to work



Getting the amp wasn't exactly a cakewalk either. FedEx lost my package despite saying it was signed for by me. After a couple of days it turns out they delivered it to someone else. Unfortunately, I ended up exchanging the amp because one of the mount screws was loose. I got the amp from Sweetwater and the experience was fantastic.


My buddy Chris and I picked up the plywood and pvc and got to cutting. Unfortunately, everything I read said 3/4" mdf was actually 3/4"...the mdf I got wasn't. It was actually 11/16. As a result, a lot of the cuts had to add/subtract 1/16 or 1/8th of an inch.


I don't have any pictures of the ports (I forgot) but this was our setup:




Despite the mdf not being the right thickness it looks like we accounted for everything properly. The dry fit went together great:




At the end of the day I noticed the dust collector had picked up a good static charge hah.
 

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Discussion Starter · #3 ·
I've been in relatively frequent contact with Mark since I got the speaker. One thing to note about anyone picking up a UXL-18. It has a gasket included now and you need to thread the mount screws through the gasket to support the basket. 10-32 screws work great for this, but 1/4-20 probably won't since they are too big.


Unfortunately, I hit a bit of a snag with the speaker :\

When I first got it I noticed there was a spot of rust (or something that looked similar on it). Mark said it was a problem with the finish but shouldn't affect anything.


After getting my amp and doing some test to make sure there wasn't any major issues with the speaker I noticed one of the magnets has a 7/8" crack in it



It doesn't seem to affect anything but I'm waiting to hear back from Mark to see if it's serious.
 

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That driver must have taken a pretty big spill in shipping. I have a few drivers with cracks in the magnets and have been using them for years. My mal-x 21 has a 2" crack in the middle magnet but it doesn't matter as they are glued pretty well. You should take a pic so we can see the crack.
 

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Quote:
Originally Posted by hotsho111  /t/1484470/it-finally-begins-the-uxl-18-build#post_23593312


Here is a pic of the crack:

Ahh ok, I was thinking it was down the side, like it was cracked in half. Thats nothing to worry about, it won't do anything to the performance. I've seen and have much worse than that, my 21 the whole slug is cracked in half lol.
 

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Discussion Starter · #8 ·
Mini update. Since the openings in the 2 pieces of bracing are all the same I made a single template that was 4.75 x 4.75 and it came out great!


This was the little jig I made:



After cutting it out:



And here is the finished template




Also, why you always wear a respirator when working with MDF:



I cut this in 1 pass with a Freud 50-509 bit and it was like a hot knife through butter
 

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Discussion Starter · #9 ·
Almost got the first template done but I have a quick question for some more seasoned woodworkers.


I am planning on doing 5/16" roundovers on the inside bracing and 3/4" roundovers on the outside corners. The router I'm using is a 27000 single speed hand router.


I noticed the 3/4" roundover bit has a max speed of 16000 and the 5/16" bit has a max speed recommendation of 18000.


I'm generally one for always following guidelines but would there be issues running this bits at that high a speed? Anyone use a router speed controller before?
 

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The larger the bit, the higher the speed at the cutting edge vs a smaller bit at any given shank speed. So the idea is you slow down the router for the big bits. I have no practical experience with this, but I'd imagine you might over heat the bit assuming the router has enough HP. Probably more likely that the router might struggle with a bit that size if it doesn't have a speed control.
 

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Routing the inner bracing is a complete waste of your time. It won't do anything but wear out your bit.
 

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Quote:
Originally Posted by hotsho111  /t/1484470/it-finally-begins-the-uxl-18-build#post_23597438


I thought there was some benefit of getting ride of sharp edges though no?


**Searched another thread on here, and it looks like it's not necessary. My OCD side may compel me to do I though hah

Nope, no benefit at all, I can't understand for the life of me why people do it on sealed sub boxes (other than OCD of course lol)
 

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Quote:
Originally Posted by N8DOGG  /t/1484470/it-finally-begins-the-uxl-18-build#post_23597797


Nope, no benefit at all, I can't understand for the life of me why people do it on sealed sub boxes (other than OCD of course lol)

Definitely some OCD but I think it's more of a pride thing. It feels good to build something and one wants to put everything into it. Many people will route the bracing which is completely unnecessary but it looks nice ... up until the box is closed. Then yes, at this point all that effort will be for nothing.
 

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Discussion Starter · #17 ·
Quick question on the front baffle. I was going to double it up with a 3/4 piece of mdf, then glue a plywood ring to that which the screw anchors will be glued to. IE: MDF sheet+MDF sheet+Plywood ring


Would it make a difference if I just made the baffle a piece of plywood and didn't bother with the mdf+ring combination. IE: MDF sheet+Plywood sheet


You can check out the piece I'm talking about in the first post (it's labeled Baffle)


I need to get a quarter sheet of plywood anyway, so it's not going to affect the cost at all
 

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Discussion Starter · #19 ·
Just to clarify (I'm not sure we're completely on the same page)


Currently I have it as a 25x25 3/4" piece of mdf, glued to a 23.5x23.5 3/4" piece of mdf glued to a 18inch diameter (roughly) 3/4" plywood ring (since anchors grip better in the plywood than mdf).


I was thinking of replacing the 23.5x23.5 mdf and the ring with just a 23.5x23.5x3/4" piece of plywood and screwing the anchors into that.


That way the front would be a 25x25x3/4" mdf sheet glued to a 23.5x23.5x3/4" plywood sheet (which the speaker would mount to)


Hopefully that makes sense
 
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