[d_c]

I built this sub a couple of weeks ago for the HT setup in my parents new house that will be completed in April. They were at my house over Christmas and watched a few movies when my dad decided that he needs a decent bit of sound for their new home. I will be making 7 other enclosures for the 7.1 and two for the lenai. All of this needs to be stealth in design, with the surrounds behind screens in the ceiling and the LCR, sub, and electronics in a 9' long, 24" x 24" cabinetry below the screen. All behind acoustic fabric or cabinet doors that my dad will build. Not a perfect room, not perfect THX positioning, but I'll try to get them close with some good equipment. I'm making a bastardization of the Zaph ZDT for the LCR, and the Meniscus Classix II for the surrounds. Power to the 7 is Onkyo 709.

Completed:
http://s20.photobucket.com/user/ocd_reef/media/Home%20Theater/IMG_3392_zps5c24eb4f.jpg.html

SI 18 D2D2
Re: 3.5 Ohms
Fs: 17 Hz
Qes: 0.41
Qms: 5.8
Qts: 0.38
Le: 3.2 mH
Sd: 117841 mm^2
Vas: 411.9 l
BL: 19.7
Mms: 416 g
Cms: 208.8
Sensitivity (1W/1m): 88.7 dB

Recommended enclosures: 18"
Sealed = 6 ft^3
Ported = 7 ft^3 tuned to 20 Hz
Cutout: 16.7"
OD: 18.5"
Mounting depth: 9.5"
Mounting flange to top of surround: 1.5"
Displacement: 0.25 ft^3


I used a single SI 18 D2, which is a 2x2 DVC driver wired in series for a load of 4 ohms at the amp.

The amp for this is a Behringer iNuke NU1000DSP, which I am very unfamiliar with, but I know that it claims to offer 1000w at 4 ohms bridged. To protect the driver, the gain will have to be cranked down to provide a max of 600w. In reality, the driver should be able to handle much more power for x-mech, but for the planned 6 cubic foot sealed enclosure, thermal handling is the issue with more volts. This amp has some DSP, so I look forward to learning how to use that. I found a mod for a quiter fan, Nexus 80mm Real Silent Case Fan - SP802512L-03. I wanted to go with the EP4000 since I have 3 of them on the subs at my house and love them for their power and dependability. Since SI designed this to be an efficient HT sub, 600w is all it needs, 750w for peaks.

The enclosure is sealed due to my height and depth requirements of the cabinetry in which the sub will be housed. I can go 22.5" high, 24" from to the wall, and around 24" for the width for the sub to slide in to. So, the outside dimensions of the enclosure will be 22" tall, 22" deep, 26" wide, internal 19x20.5x22.5. This will allow me to have a double layer baffle and single layer surround, with single layer walls for the rest. This makes for 5.07 cubes on the inside, and I will stuff with 6# of polyfill to make up for the other 1 ft., for a total of 6(ish) cubes. The material is 3/4" MDF and finished with Kilz primer and Rustoleum Truck bed coating.

 

[d_c]

Sawdust



A dry fit

 

[d_c]



 

[d_c]

First run with the Jasper Jig and the new plunge router was a great success, except I broke my cutting bit on the last pass. Well worth the $7 even if it was disposable. I countersank some screws so that it wouldn't move on me after the 2 pieces separated

 

[d_c]

I pulled off the plastic surround to get a better look at the mounting holes. Perfect fit for the driver, marked some holes for the fasteners (10-24 hex button heads)




I can't seem to drill at a 90 and don't have a drill press, so I made a little jig for that with some scrap. It did the trick.




I could only find 1 1/2" bolts at the store, so I countersank the holes for the T-nuts. I think it will help grip the T-nut once the Gorilla glue foams up around it. Effed up a few of them with the original bolt hole a bit too close to the driver cutout. I found a giant 45 chamfer bit on ebay for cheap for the inside of the baffle.

 

[d_c]

I use some washers on the other side so I can pull the T-nuts in tight to let the glue cure



Figured out a way to keep the Gorilla glue off of my fingers when gluing the T-nuts. Just used the bolt to hold it since I like to make sure they all match before installing them to avoid hang-ups

 

[d_c]

need - more - clamps




This is a very solid driver for the price. The paper cone is meaty, stitches on the surround is a nice touch, basket is solid, and everything looks put together with care. There's some extra glue on the rubber gasket ring, but doesn't really bother me. I wish the ring was made out of something different. It's floppy, for lack of better words. I broke the driver in for 12 hours with a 20hz tone, and then left it hooked up at a lower voltage to keep it moving when the rest of my music played through the other subs for about a week. I have it sitting next to my desktop and it actually produces decent bass just sitting there a couple of feet from my head. My desktop setup is two Mackie SRM450 v1 and two 30" Titan T48s. Sounds pretty good for a computer setup... the pair of 36" THTLP will sound better.




Some zip ties to keep the series connection wire from bouncin'



A few sheets of 1/2" Arauco for the next project...

 

[d_c]

I used a 2" flush edge bit for the edges, bondo for the larger cracks, a blunder on my poor edging skills, and screw and nail holes. Then I shaped the edges with a 3/4" round-over bit on the outer edges and a 1/8" round-over for the edge that surrounds the driver. I did manage to snap a pic with the phone.

 

[d_c]

Routed out a recess to flush mount the wire terminal





Kilz primer, sand, fill, repeat, 4 times at least. I won't be using PL for enclosures that I plan to finish next time. It doesn't sand well and leaves a lump at all of the seams that has to be covered with bondo. Back to Titebond II.




Flat black first because it's cheaper than 2 coats of the Rustoleum bed liner. 3/4 can for this.

 

[d_c]

I used about 1 can of Rustoleum Truck Bed Liner in a single coat, and double coat at all of the corners and bottom, Filled with 6# of Polyfill, wired, driver installed, wire terminal on, test failed, removed wire terminal, attached the wires, tested, and it sounds amazing. Love it. Thanks for the cheap driver SI, too bad I don't get to keep this one.





I'll get some better photos of it later. The reef tank makes it glow.

 

[Audiophile1178]

Very nice build!

How long did all of that take you?

 

[pbc]

By my math, approximately 29 minutes from the first post to the last.

J/k ... I agree ... looks great.

 

[beastaudio]

I love the use of the truck bed liner, and agree with your PL statement. I love the stuff to seal up things, and first learned of it building a tapped horn (f-20) and it is PERFECT for that type stuff, when you want a dead on seal and can't go back and touch it up. For exterior panels though, it is surely not fun to sand out. TB2 is a much better option there. I still use pl for bracing and if a panel is badly cut, which with my meager setup, happens sometimes. Those are also some serious roundovers! Love how it looks as well. I can get a similar texture with just flat black and my HVLP sprayer using flat black, but the peel texture is just slightly less (not assuming any sanding and a good wide throw from the sprayer). Also, a good touch on the zip-ties for the wiring, never thought of that, I usually just wire it tight enough to hold in place but good touch nonetheless

 

[ack_bk]

I had no issues using PL premium. I used an orbital sander and 150, 180, and 220 grit paper. That said, your box turned out great. Very well done sir, and liked how you documented this with pictures and words.

 

[beastaudio]



Quote:
Originally Posted by ack_bk  /t/1453468/stereo-integrity-18-d2-build-sealed#post_22861116


I had no issues using PL premium. I used an orbital sander and 150, 180, and 220 grit paper. That said, your box turned out great. Very well done sir, and liked how you documented this with pictures and words.

Ack, I use the same, but I have to say without a doubt, that after putting the panels together and whether you clamp, screw, or nail, the TB2 wipes off with water easily (I learned this too late on my latest build) where the PL does NOT. I was staining so this is a bigger issue...If painting it is not as huge of a deal.

 

[d_c]

Ha! Yeah, just about 30 minutes - I work fast, just ask my wife.

I think I worked on it 8 or 9 days total over a couple of weeks. This was a really easy build once I had it planned out, and didn't take many hours at all. Many small steps and waiting though.


@Beast - I used only PL on my horns too. The stuff is awesome except it gets all slippery if you try and hurry up a panel. It makes a mess fast and my skin falls off of my hands before the PL will. I will be using it again on the THTLPs I'm getting ready to make here in the next month or two. I love the look of the flat black too, but I don't have an HVLP.


@Ack - I used the orbital too, but still had a bump at the seam. So I scraped the seam with a razor, used a swipe of Bondo over the seam, then some 220 with the orbital to make 'er smooth. Now that you mention it though, I used ply on my last build with PL and didn't have an issue with the seams. I'll bet it's because hardwood sands at the same rate as PL, MDF is much softer and sands away faster.

 

[nograveconcern]

PL works good with Duratex because it's more forgiving of minor inconsistencies. I can see it not being the best for a smooth finish but shouldn't be a huge deal with those surgically precise cuts you have.


You shouldn't be trying to sand off PL though. Use a sharp chisel to trim the squeeze out once it dries, or a flush router bit if you are lazy. And definitely don't wipe or smear it trying to remove the squeeze out before it dries. Let it dry first.


D_C, I really like the look you get with the bed liner. I just know I would ding it all up before I got it from the garage to the HT.

Any reason you did that 45 on the baffle? It looks cool, but I can't figure out what it achieves.

 

[Gorilla83]

A few tips/tricks I learned with working with PL:


-Try not to wipe off excess outside the box while it's still wet. Wait until it's dry and then peel/scrape. It spears rather easily and it's hard to sand off as others noted.

-Be careful using a flush trim bit to remove the dried glue. I've had some tearout occur because the glue was stuck to the box and it ripped the wood out when it removed the glue.

-I've said it many times, but always wear gloves when working with this stuff.


This stuff is great for sealing gaps and/or inside the box, but I agree with beast when I say I prefer to use normal titebond when putting the components together.

 

[bhazard]

Gorgeous build.

 

[d_c]

Updated pics
http://s20.photobucket.com/user/ocd_reef/media/Home%20Theater/IMG_3393_zpsb4864095.jpg.html

http://s20.photobucket.com/user/ocd_reef/media/Home%20Theater/IMG_3392_zps5c24eb4f.jpg.html