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2 Mal-21s in 50 cu ft? Ported to 12Hz?

post #1 of 17
1/8/13 at 3:06pm
Thread Starter 
~50 cu. ft. enclosure with two Mal 21s in a dual opposed fashion, but manifold-like. Ported with a 12Hz tune.

I am considering doing this.

1. I need to use these two Mals.
2. It seems to model pretty well in WINISD.
3. I have talked the wife into this as part of our living room entertainment center.
4. I need to build a frame on this wall anyways, to hold the Black Diamond screen material I "acquired", so this will be "part" of it.

This sketchup was just a quick model to show the manifold placement i was thinking about.

Thoughts?

My concerns.

Manifold width. Curved corner to back of manifold? Angled wall in manifold? In the sketchup the manifold opening is 8x30.


Port size

I modeled it with two 2x20 slots about 19" deep. It show almost 37 m/s with 3200 watts at 11-12HZ

I'll do a model of the room and the entire box/entertainment center idea later today or tomorrow.





Steve
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post #2 of 17
1/8/13 at 3:11pm
Yup. Do it!

The Mal-X 21 models pretty good in about 25cuft and tuned as low as you can.

I endorse this build. smile.gif
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post #3 of 17
1/8/13 at 3:35pm
Looks like a coffin for Andre The Giant!!! biggrin.gif
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post #4 of 17
1/8/13 at 3:48pm
Thread Starter 
Hahaha. "Coffin" build it is.

Scott, would I want to tune lower than 12? It seemed to fall off quite a bit going lower.
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post #5 of 17
1/8/13 at 3:53pm
ermahgerd pls poast many pix.

k thx.


english: oh my god please post a lot of pictures.

smile.gif
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post #6 of 17
1/8/13 at 3:58pm
Quote:
Originally Posted by MoFinWiley View Post

Hahaha. "Coffin" build it is.
Scott, would I want to tune lower than 12? It seemed to fall off quite a bit going lower.

That really depends on you and your desire for whatever cutoff. There will be a tapering off in output but your room will make up for it.
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post #7 of 17
1/8/13 at 4:00pm
Quote:
Originally Posted by whiskey_face View Post

ermahgerd pls poast many pix.
k thx.
english: oh my god please post a lot of pictures.
smile.gif



biggrin.gifbiggrin.gifbiggrin.gif
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post #8 of 17
1/8/13 at 5:32pm
If feasible, I'd consider two separate boxes at opposite mid-wall positions to eliminate all odd-order modes, per Welti.
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post #9 of 17
1/8/13 at 6:06pm
Thread Starter 
Quote:
Originally Posted by noah katz View Post

If feasible, I'd consider two separate boxes at opposite mid-wall positions to eliminate all odd-order modes, per Welti.

I wish, but I am pretty limited with this room. I have the lots of floor space in just one part of the room.

The room is our everyday living room on an open floor plan 1st floor.

When I get to do a dedicated HT in the basement the layout will be better (I really want to do a DBA)
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post #10 of 17
1/9/13 at 1:07pm
Thread Starter 
LOL @ my use of "acquired" one of my coworkers said it makes me sounds like I stole the screen material, which I did not, FWIW. I have a friend that installs them. This one is a defect 104 inch one(defect is 4" from corner)...I currently have a cheap 92" screen...All I have to do is build a frame to tension it.




Steve
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post #11 of 17
1/11/13 at 10:33am
That's like 5 whole 4x8 sheets glued directly together. biggrin.gif Coffin indeed.
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post #12 of 17
1/11/13 at 11:23am
Quote:
Originally Posted by Scott Simonian View Post



biggrin.gifbiggrin.gifbiggrin.gif

Thank you for that.
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post #13 of 17
1/11/13 at 12:59pm
Thread Starter 
Quote:
Originally Posted by BassThatHz View Post

That's like 5 whole 4x8 sheets glued directly together. biggrin.gif Coffin indeed.

I have been pondering that fact. I am going to redo this drawing to hopefully be around 6 sheets of 5x5 BB if I can find some in my area. I will have to resort to stick bracing because I would need another 4 sheets if I didn't.
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post #14 of 17
1/11/13 at 1:06pm
I wouldn't be concerned with 37 m/s of air speed. I have had higher than that with no issues or chuffing. This is perfect for those drivers
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post #15 of 17
1/11/13 at 4:06pm
High port air speeds at subsonic frequencies seems like it would be a significant problem. More so than higher more audible frequencies. You're not so likely to hear the fundamental because reduced hearing sensitivity that low, but the chuffing / turbulence sure will be in your range of hearing and will be that much more obvious.
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post #16 of 17
1/11/13 at 4:30pm
Quote:
Originally Posted by Stereodude View Post

High port air speeds at subsonic frequencies seems like it would be a significant problem. More so than higher more audible frequencies. You're not so likely to hear the fundamental because reduced hearing sensitivity that low, but the chuffing / turbulence sure will be in your range of hearing and will be that much more obvious.
You don't hear low frequency waves passing through the duct at high mach as chuffing, you hear the friction of those waves against the duct, and that tends to be in the midrange.
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post #17 of 17
1/13/13 at 1:21pm
Thread Starter 
Thanks guys, I was hoping the ports weren't going to be an issue.

The are of the manifold openings match the SD of the driver, is this acceptable?




Steve
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