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Discussion Starter · #1 ·
Hey everyone, I built this thing back in the summer and I'm finally getting around to posting about it.

I was humming and hawing about what to buy/build for a sub, playing around in WinIsd and skulking in the forums, when I found a Rockford Fosgate Rfd2112 in a pawn shop for $45. Done deal. Now what kind of box to build.

Then I found a Behringer Europower EP2500 on Kijii for $200. More power than I need (the Rfd2112 is 500W RMS) and no HPF. I played around a bit more and came up with a bandpass design that should control cone excursion while providing good bass for both movies and music.

Unfortunately my hard drive crashed and I don't have my files any more but the box ended up being 16.25"x16.25"x47" with a one cubic foot sealed chamber inside and four 4"x12" ports.

I grabbed some bits and pieces from work (working at a lumber yard can have its advantages) including a scrap piece of 5/8 mdf and a part sheet of 1/4 mdf. I pre cut the panels at work and put it together in a weekend.

And I'll figure a way to shrink the pics on my phone so I can post 'em.
 

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Discussion Starter · #3 ·
Very innovative! How does it sound?
At first, terrible.

Man was I angry.

Then I learned of my major mistake, in WinIsd I had aimed too low with the bandpass response curve! I actually read up on what frequencies the bass in music was, re-did my design, chiseled open the box and cut the ports from 25" to 12".
Sealed it all back up again, waiting very impatiently for the caulking to cure. Hooked I back up and presto house shaking bass.
 

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Discussion Starter · #4 ·
So as I said I precut everything at work.

Here are some of the build pics. I drilled the holes for the ports with a drill press after clamping the end piece and two braces/port supports together and marking them for future alignment.

Using a milk crate is a great support for cutting circles out with the jig saw.

Everything is glued and brad nailed except the top which was caulked and screwed.

I figured commercial door bumpers would work great for feet. And they do. They don't slide on the hardwood at all. You have to lift it up too move it around.

My old box with my new box.

And I ended up standing it on end and covering the ports with a cloth to keep things out.
 

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Discussion Starter · #6 ·
Nice build. Do you remember what the tuning was with the 12" long ports?
Thanks Mike!

I don't remember, my hand written scribbles say that I had originally tuned it to 22 with the longer ports. I'll snag a copy of WinIsd onto a jump drive today at work, I mean after work :). (The only internet at home is through my iphone) I'll also try and post the specs on the RFD2112.
 

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Discussion Starter · #8 ·
Cool build. We don't see too many band pass alignments for ht use. Are you happy with it so far?
Thanks. Compared to the same speaker in a sealed configuration, it makes a huge difference. I had pondered ported, but without a HPF I couldn't get a good model going. The bandpass design gave me the boost in music frequencies while controlling cone excursion in the lower frequencies. I haven't noticed any boominess or 'one note wonder' aspects to it. It really blends well with my mains (JVC SP-D6000).

Finding the right levels on my receiver and amp was a little nerve wracking.....keep turning it up in a scene until the speaker hits it's max travel and hope you don't break it.

I am happy, but of course I've been bit by the bug. Do I stick with the basic design and just make a better looking version of it come the nicer weather? Or do I go for fast cheap and dirty 2, designed to go behind my couch and get another woofer for something up front or.......well you guys know how it goes.
 

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Discussion Starter · #9 ·
Hee hee, fell asleep on the couch with some Dub playing and my wife came in to the living room to turn down the music as "everything in the kitchen is rattling". Whoops :)
 

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Nice construction quality! You should have reverse mounted the sub to vent the voicecoil(s). I design all my bp's where the speaker basket is always in the vented chamber for cooling.
 

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Discussion Starter · #11 ·
Nice construction quality! You should have reverse mounted the sub to vent the voicecoil(s). I design all my bp's where the speaker basket is always in the vented chamber for cooling.
Thanks!

Good point about the voice coils. I was more concerned with seeing the speaker move to check for over excursion. Now that I know it's fine I will certainly reverse mount it in the final version of the box (just waiting for warmer weather so I can work out on the back porch).
 

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If you use Horn Response to design the enclosure, then you can account for excursion prior to sawdust!
 
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