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It finally begins! The UXL-18 Build

post #1 of 251
Thread Starter 
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:
The exterior dimensions are 25h x 25w x 30d made of 3/4 MDF with plywood for the speaker mount.

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


Dimensions of the various pieces:



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





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

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).

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.

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)

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
Edited by hotsho111 - 8/3/13 at 4:38pm
post #2 of 251
Thread Starter 
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.

Edited by hotsho111 - 8/3/13 at 8:33pm
post #3 of 251
Thread Starter 
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 frown.gif

It doesn't seem to affect anything but I'm waiting to hear back from Mark to see if it's serious.
post #4 of 251
Nice build, I hope the driver is okay.
post #5 of 251
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.
post #6 of 251
Thread Starter 
Here is a pic of the crack:
post #7 of 251
Originally Posted by hotsho111 View Post

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.
post #8 of 251
Thread Starter 
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 biggrin.gif

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
post #9 of 251
Thread Starter 
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?
post #10 of 251
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.
post #11 of 251
Routing the inner bracing is a complete waste of your time. It won't do anything but wear out your bit.
post #12 of 251
Thread Starter 
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
post #13 of 251
It's great to see this build coming together!
post #14 of 251
Originally Posted by hotsho111 View Post

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)
post #15 of 251
Originally Posted by N8DOGG View Post

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.
post #16 of 251
Thread Starter 
Originally Posted by Jay1 View Post

It's great to see this build coming together!

Haha, thanks!

I was going to put a list together of thank you's to people who helped, but it ended up being so many people covering so many different things I lost track
Edited by hotsho111 - 8/5/13 at 11:57am
post #17 of 251
Thread Starter 
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
post #18 of 251
You can definitely do a plywood/MDF laminate.
post #19 of 251
Thread Starter 
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
post #20 of 251
Yup, that is completely legit. You might want to use something like pl premium to glue them together, depending on how smooth and straight the plywood is.
post #21 of 251
The replacement of the inner baffle with plywood would eliminate the need for the plywood ring. Nice looking build, should add some serious bass to your system.
post #22 of 251
I make all my boxes with the inner baffle in 1" plywood. The plywood ring would work fine also though, it's just adds more work.
post #23 of 251
Thread Starter 
Ya, I think I'm just going to make the baffle plywood, a little bit less work.

I tried finding some baltic birch but didn't have any luck locally. My local lumber yard has some high quality birch though that I think should be good.

post #24 of 251
Thread Starter 
Quick question, any issues using 3/4 plywood for the baffle. That should be strong enough right? I could go with 1" but the fittings I got are just long enough for 3/4" plywood (13mm length versus the longer 20mm set)

My local lumber yard has some really nice birch ply (I think it's AA) but I don't think it's baltic birch. People seem to put BB on a pedestal but it's not the easy stuff to get locally. I can get a big enough piece online though. Is it worth it going for BB over some regular high quality birch?

I got some low head socket cap black oxide screws from mcmaster-carr and annoyingly they are all already covered in brown rust. The set I got wasn't oiled at all :\
post #25 of 251
ya 3/4 is fine, I use 1" because it's easy for me to get, just down the street. You can use any decent plywood, don't bother with BB, just get a piece that won't have a void on the mounting area.
post #26 of 251
People use BB because it is 13 layers of dense birch. Most birch ply is a birch veneer over pine. It doesn't matter though. Any low void cabinet grade plywood will work. More plys the better.

I've not had anything from McMaster show up rusted. It must have been exposed to moisture. I would be inclined to return it.
post #27 of 251
Thread Starter 
Ya, I want to return it, but it would probably cost me as much to send it back as I payed for it :\

Anyway, got the braces cut out and routed.

Everything measured up.

Got the first piece cut out using a template I made. It sucked, I started cutting one sheet and realized the original template I made was the wrong size. I then tried making it again and 4 times in a row ran into issues (mostly clamps sliding just a bit). So I finally clamped everything down and screwed the pieces together. That template came out fine hah. Started on a fresh sheet and it came out great

I used the first piece as a template for the second

Obligatory 'you can never have too many clamps' picture

Cancer mountain...the mess this made was unbelievable...

I forgot to take a picture of them outside, but here are the pieces

Called it a day after cleaning them up. Gonna round over the braces tomorrow. Sorry N8, I gotta do it!
Edited by hotsho111 - 8/10/13 at 5:37pm
post #28 of 251
LOL!! Hey, you gotta do what you gotta do tongue.gif
post #29 of 251
Thread Starter 
Didn't get a chance do roundover today because I need to exchange the bit I have.

I cleaned up the pvc and have a quick question for everyone.

I'm using precision port flares with 3" pvc for the actual tubes.

I did a test a while ago trimming the pvc end with a dremel so I could use the precision port connecting ring to attach the two:

I tried making a jig to start cutting these today and it didn't go so well.

I was thinking of just lining up the ends of the tube and the flare and gluing them together, then putting some pvc glue over that. I'm just not sure if that would be strong enough.

Any ideas? I'm gonna punt on this for now.
post #30 of 251
Thread Starter 
Hey everyone small update (I don't get to work on the project much during the week).

I picked up a nice rabbet bit set and playing around I can get a perfectly clean cut to line up the flare

This is how it looks joined from the front

and from the back, some parts look a little wider because, fun fact, the inside of pcv pipe isn't perfectly round (but the outside is...). The inside diameter between the pvc and precision port is also about a 1/16 of an inch off. PVC is about 3.06 inches in diameter and the precision port is about 2-15/16

Something else that's nice about using a rabbet bit instead of a dremel grinding bit...no melting pvc. It shaves off tiny pieces instead.

The plan is to trim the pvc to accept the port flares tomorrow and round over the interior bracing. If I get lucky, routing the hole in the back for the banana terminal.
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AVS › AVS Forum › Audio › DIY Speakers and Subs › It finally begins! The UXL-18 Build