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Discussion Starter #1 (Edited)
I'm working on a build of two CSS SDX15 subwoofer boxes for my almost-finished home theater. This is my first time building a speaker box. My previous sub was a Dayton Titanic 10" kit sub with a pre-assembled cabinet. I don't have much woodworking experience so I was a little nervous about screwing up something. So far, things seem to be going pretty well. :R

The plan is to use two 9.8 ft3 ported boxes tuned to ~18hz in my ~1200 ft3 home theater (11.5x13x8). I've already bought a Behringer EP2500 amp and a Reckhorn B-1 subsonic filter to use with the subs. I know that this setup is overkill :dizzy: in such a small room, but I like symmetry and two is almost always better than one. :dumbcrazy: I decided on a 6" PVC port for simplicity, as I was able to pick it up at a local plumbing supply place. With my intended box dimensions (28w x 25h x 32d), an 8" port would be impractical. Modeling shows that I could be on the high side for port speed, but I plan on flaring both ends and I don't think I'll ever run enough power through them to have port noise issues. Real world testing to come later. :whistling:

The box build has given me the opportunity to buy a few new toys, including a new Bosch dual-base router, a Jasper circle jig, and a Harbor Freight dust collection system. :spend: I already had a table saw but I added an extension table to it using scrap MDF. Add router bits, dust collection accessories, wood, the speakers, the amp, the subsonic filter, odds and ends, and it's been a tough month or two for the wallet. :spend: :dizzy: I guess someone has to keep the economy going. :joke:

At my current work rate I expect to be done in about a month, more or less. I have some unique ideas for finishing because of the intended placement near the front of the room under the screen. More about that later.

Some pictures and updates to follow.
 

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Discussion Starter #2 (Edited)

The obligatory size-reference shot with the subs.


A sketchup of the box.


Another view of the sketchup of the box.


WinISD modeling. Remember that there will be two of these.


The FR graph.


Cone excursion at 600w with a 10hz ssf. I don't intend to ever run the sub this hard.


The dry-fitted box sitting atop the table saw. This gives you some idea of the scale. I was a little shocked at the size when I first did the dry-fit. Also a shot of my high-tech DIY extension table. I can rip to 36" wide now, though!


Another view of the dry-fitted box, with a tape measure for some scale.


Dry-fitted bracing. These will have different placement in the final box, as the port should be in the 18" range. I may shuffle the bracing arrangement around a little and use more poplar bracing on the back-half and MDF on the front half as port support.


The first port holes and front speaker holes cut.
 

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Thanks guys! I'm really enjoying the project so far. I would have started a few weeks ago but I was doing some spring cleaning in the garage. I'm almost done reorganizing. I put a few things up on Craigslist and I've almost cleared out all the stuff that needs to be donated/sold/tossed. Added shelving and sorted all my stuff into bins. I also had to do a few modifications on the table saw to improve the dust collection capability. MDF dust was getting everywhere! :gah:
 

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Is it too late to add bracing to that rear wall? Your side walls are very well braced, but I don't see anything on your rear.
 

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Cone excursion at 600w with a 10hz ssf. I don't intend to ever run the sub this hard.
Plan on 1000 watts per sub as a worst case.....your usage and expectations will change a lot between now and a few months after the subs are done. You'll be listening louder than ever before, I can guarantee it :T
 

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Discussion Starter #9
Plan on 1000 watts per sub as a worst case.....your usage and expectations will change a lot between now and a few months after the subs are done. You'll be listening louder than ever before, I can guarantee it :T
I don't doubt that I'll be listening louder than I was with my 10" Dayton. :heehee: If I bump the ssf to 12hz the excursion will be under control at maximum output of the EP2500. By then I should be getting structural issues. :hsd: At that point, the worst spec in my setup will be port speed at around 32.5 m/s.
 

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How is your build coming along? I am contemplating building one of these as well, so I am curious to see how it turns out. I have a similar size room, but will one build one in a slightly smaller box.
 

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Discussion Starter #11
How is your build coming along? I am contemplating building one of these as well, so I am curious to see how it turns out. I have a similar size room, but will one build one in a slightly smaller box.
I cut a bunch of the hardwood bracing but other than that haven't had time to make much progress. It's kind of a slow build, and I figure I won't be done for about 4 weeks. Also, I ordered a new jigsaw to cut the MDF bracing so I'm waiting for that to show up as well. I'll update the thread once I start cutting the bracing and gluing the box up.
 

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Discussion Starter #12
Well finally an update. A week-long vacation and a busy time at work has kept me from getting done but I've been able to make some progress. I managed to finish the bracing for one of the subs.

This is the test fit of the SDX15 in the front baffle. Basset-approved. :bigsmile:


A little more detail of the bracing arrangement:


I also cut and applied the foam lining:


And more of the foam:


For the first box, I still need to finish the inside and outside port flares, attach the binding posts, drill out the driver mounting holes and install the T-nuts, and glue it all up. I think I'll be able to finish that up this weekend and then I can get started on the second box, which I hope will go a little faster.
 

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Those are going to be monsters.....:T
 

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Update time! Made some progress over the weekend.

The obligatory clamps everywhere pictures:




You just can't have enough clamps. :R I'll probably pick a few more of the longer ones up for the second box to make my life a little easier.

Here's a little detail of the front of the port. The flaring was done with a 3/4" roundover bit. The rear of the port got the same treatment:


There is a lot of finish work to complete on the box, including trimming off some edges with the router, sanding, painting, etc. But while I finish the second box I figured it couldn't hurt to use the first one. :devil:

Here's where it will sit, more or less. It's really impossible to get the feel of the scale from a picture. In the room, it looks enormous. Two is going to be borderline hilarious. :gulp:




The sub sounds great! It's pretty incredible how much air it is able to move at about 15hz. I do have a bit of a hum problem that I have to get sorted out, but it's nice to feel that the construction came out well enough to actually work. Because I've had a chance to test it a little, I feel a lot more confident about starting the second box.

My unscientific impression is that the box has very flat response at the listening location. Compared to the 10" Dayton I was using before, there seem to be much smaller fluctuations in the response curve. I won't do any serious testing and tweaking until I get the second box finished and in place.

Thanks to everyone so far for the help and support! :T
 

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Looking great. Nice work on the execution of the enclosure. 2 of those aught to provide a very nice low end anchor for your HT. What are you going to do for a finish? Nearly everyone seems to have to battle the dreaded hum issue.
 

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Very nice craftsmenship.

Did you keep records of a cut list?

If you did it again, would you increase the port to 8"?
 

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Discussion Starter #20
Very nice craftsmenship.

Did you keep records of a cut list?

If you did it again, would you increase the port to 8"?
Thanks! I didn't keep a cutlist but I still have a second box to build, so I've got all the pieces disassembled. The size is very specific for my location, though, so I'd recommend following whatever needs you have size-wise and building the box to your own specification.

I haven't spent too much time with the sub because of my work schedule, but so far I haven't noticed any port noise, even on a 15hz test tone. An 8" port would have required an elbow in my box which would have added some complexity. After I finish the second box, I'll be doing some more serious testing and equalizing and I can give you a better idea of whether the port was too small or not.
 
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