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Discussion Starter · #1 ·
Whats up everyone. Just thought I would post some pics of my subwoofer build.

I decided on two 4.5 cuFt downfiring enclosures tuned to 17hz with a 2" x 14.5" slot port. Each housing one eD 13Av.2 driver. Most likely going to be powered by an ep2500.

The outside dimensions are roughly 48" X 16" X 16". I am a little worried about the first port resonance. It models to 122 hz. Hopefully it doesnt turn out to be a problem. I have heard it is less of an issue with slot ports that have multiple turns. I dont know how accurate that is, but hopefully it will be fine.

Here are the WinISD graphs.
 

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Discussion Starter · #3 ·
Here are some pics of the bracing and with the front on. The front is not permanently attatched yet. I'm gonna hold off on that for awhile.
 

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Discussion Starter · #6 ·
Chris at Elemental designs helped me with the design. I made a few changes to the port. I will definitely be rounding over the port entrance. I was thinking a 3/4" roundover bit. Is that pretty much the standard?
 

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I think you want the flair as big as possible. For example a 4" precision port flairs out to almost 7" (~1.5" round over). Looking at your material it looks like you have .75" on the bottom and 1.5" on the top. But a 1.5" round-over would cost a pretty penny and you would probably lose a finger :). I bet .75 will be fine. Good luck!
 

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Discussion Starter · #8 ·
The top and bottom are both 1.5" and the sides are .75". I also wanted to do a little roundover on all the exterior edges. I hope I got enough meat on the sides of the port to do that. Otherwise, I would have to add another .75" to both sides. I would rather avoid doing that though.
 

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Discussion Starter · #10 ·
Heres a little update. got the legs and base plate finished. I'm a little to lazy to drive to Depot right now for more MDF for the second one, so I am gonna start sanding and wood filling this.

I was going to do truckliner finish on these. Looking at this now, I might try to do a nice satin black. So I will most likely Bondo the whole thing. A friend of mine has a real nice sprayer. Anyone have any tips on a satin black finish? Is Bondo necessary, since I am not going for a piano black? Also any recommendation on the type of paint?
 

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A quick note on the port resonance. Since your port resonance is at about 120Hz there are a couple simple ways to deal with this issue. The first is simply using a fourth order crossover at no higher than 80Hz. If this is not possible or you want the subwoofer to be used at a higher frequency* you could measure the port resonance and use a notch filter at the exact frequency at which the port resonates. Personally, I use the former solution with my build that as a first port resonance at 120Hz.

*Due to the density of your bracing it should be noted that using your subwoofer at higher frequencies might result in audible cabinet resonance.

As far as rounding over the port goes 3/4" will be fine. Using a larger radius would allow for less impedance of airflow, but it is unlikely these differences would be audible except at extreme SPLs if at all. From the looks of your pictures it doesn't seem as if the exterior of the port is rounded over. I suggest you do this as air is pushed and pulled from this area and will be impeded by these edges.

Sorry if any of this is a little to late, I just noticed the thread.
 

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Discussion Starter · #14 ·
I am definitely not going to crossover any higher than 80hz. I believe my Onkyo 875 uses a 4th order crossover.

I just finished rounding over the port opening.

Definitely not too little too late. This is my first build, and I appreciate any feedback at all.
 

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Discussion Starter · #15 ·
So one enclosure is almost ready for paint. I got a little more bondo work to do. The prep work for the paint is much more involved than the actual building of the cabinet. I am a carpenter and I have never really worked with bondo. I went out and bought a random orbital sander. Made the work a little easier. I am probably going to prime some time this week with some sort of high fill sandable primer. I will see how it looks after that before deciding on the type of finish to do. Its gonna be hard to find some time to work on this in the next couple of weeks. I will post some pictures of the progress tomorrow.
 

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Discussion Starter · #17 ·
One box is built and prepped for paint. I havent had anytime to work on them in the past few of weeks. Probably wont have anytime for the next couple of weeks. I just checked the status on the subs though, and they should be arriving today. I will post some pics.
 

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I also have a 13Av.2 gathering dust at the storage and hopes to build LLT box 8Cu tuned to 15-16Hz. I like the way you fold the port, I think I'll make it like that.:T
 

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Discussion Starter · #19 ·
what kind of amp are you going to be using? 8 cuFT seems kind if big. Atleast according to the guys at eD. I am a little concerned about the port. The first port resonance is around 120 hz. People have different opinions as to whether or not, it will be a problem. There's a good thread on here discussing this issue. I think its called "port length recommendations". I will post some REW graphs once it is completed. Its gonna be at least a month tho. I am getting married soon, so this project had to take a backseat for awhile.
The drivers just arrived this morning. These things are heavy and the magnets are huge. Overall seems to be well built.
 

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Im eyeing towards EP2500. Yes, i have realized 8 Cu is too much. I have tried 5Cu tuned to 18.5Hz ang it looks good to me bec. port resonance is around 160Hz. I was actually a little worried about port resonance that's why Im trying to model where the port resonance is around 160Hz or higher. Although they say it's inaudible at the listening position, I really would not like to gamble. Anyway I will also use a DCX2496 and use a 6th order crossover at 80Hz and a -15dB EQ filter at 160Hz to be sure port resonance won't be a problem.
 
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