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Discussion Starter · #1 · (Edited)
Edit:
Final build will be 9 cu ft, 18hz tune...


Gettin' ready to build the box...

2500 cu. ft. room
ep2000 for power
Reckhorn B-2 for HPF
Behringer DSP1124P for EQ

Design:
7 cu. ft., outside dimensions 20"H x 38"W x 22"D
17hz tune, 18.5" x 2" slot port 43.25" long
planning 16hz HPF

50/50 music/movies

I may change my mind at the last minute and go sealed... have to decide before I start cuttin' the MDF.

I can go a bit larger if it'll help... only if would make a big improvement though...

Thoughts?

Also, I'll have to bend the port at one corner. Do I measure the port length on the inside of the corner (shorter), outside (longer) or in the middle? (I'm guessing the middle)

Thanks,
-Todd

7cuft_17hz_vs_sealed.png

cabinet.png
 

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Discussion Starter · #5 ·
I'm maxed out at 10 cu. ft. by the time I account for 3/4" MDF side thickness and that doesn't even include the bracing or port... gives me almost 3db increase @20hz... worth it?
 

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Discussion Starter · #7 ·
Ok, you talked me into it. Here's the final comparison... I'll go for as big as possible here and get the extra couple db.

Final volume approx. 8.88 cft. including bracing/driver/port, 18hz tune, 16hz HPF.

This driver seems to really like an 18hz tune in this size enclosure. Even at 7cft. it looks a bit better with an 18hz tune.

I hit max excursion @26 hz 950 watts...

At least I won't feel like I didn't max it out... :)

Thanks for the help, I'm going to go start building.

-t
 

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Discussion Starter · #9 ·
I'll see if I can get some pics up...

Last q...

I was going to do a 3/4" roundover to flair the port. I was going to do both sides of the port on the outside (the two long sides) and one side of the port on the inside (since the other side of the port is the back wall of the sub, if that makes any sense).

How do I account for this when computing port length? I know for round ports, you subtract 1/2 the diameter of the roundover radius (for each end) to figure out the effective port length, is it the same for slot ports?

Outside port, 3/4" roundover = subtract 3/8" from actual port length?
Inside port (shares back wall of woofer) = subtract 3/16"?

I hope that makes sense... Also, the 90 bend, I was going to round the inside of the bend, can I just leave the outside square?
 

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Discussion Starter · #12 ·
Ok, I got a good start on this thing today...

I'm cutting panels and doing most of the router work in the garage but assembling it in the basement so I don't have to carry it down the stairs when it's done. :) The wife (for some reason) was shocked to see the size of some of the panels that I was carrying in from the garage. She said something about not understanding the need for a speaker of this size in our moderately sized basement.

Anyway, I've got all the panels cut, the back, bottom and sides glued together and figured out a cool way (that I'm sure someone has done before) to smooth out the corner of the port bend with some 4" PVC a bit of router work. I'm increasing the port slot width to 2.5" to keep port velocity <20 m/s as well. I've also figured out that I need more clamps.

Excuse the crummy pictures from my cell phone, I'm using it instead of our real camera to hide any flaws... :)
 

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Discussion Starter · #13 ·
Got the front on last night... I remembered to paint the port before I got to a point where I couldn't reach it. :)

It's moving along fast now. Just finished installing all the bracing and the port pieces. I'll get pics of the port detail up when I'm done picking the tightbond out of my arm hair.

Any suggestions for stuffing? Kevin's 6.35 cu ft recommendation calls for a 15% fill. I was going to do about the same and add a little less than a pound and a half of poly-fill from the local Target.
 

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Discussion Starter · #14 ·
Cabinet is done... Using my trusty Rythmik 12 to hold down the top while the glue sets. I have to test it before I finish it... How it sounds will determine if it gets a nice finish or not. :)

Thinking about brushed on semi-gloss black paint to match the trim and doors in the room.

The Rythmik will be sent upstairs for two channel duty with my Mudula MT's...
 

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Discussion Starter · #19 ·
Here's the final results...

REW plots before and after EQ with 3 filters... I tried to bring that dip up at 22Hz, but it's persistent and didn't respond well.

pre_eq.png

post_eq.png
 

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Discussion Starter · #20 ·
Some pics of the finished cabinet... I had to pull the driver out the other day and chipped the front. A bit of filler and a touch of paint and I'll be the only one that notices it, especially since I'll be leaving the grill on for the most part. I have to get another set of grill guides, I'm missing one cup for the top left guide.

no_grill.JPG

w_grill.JPG
 
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