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Discussion Starter #1 (Edited)
Not should it be done. Can it. I'm not looking for a smooth flat FR. I am looking for a typical large sealed box FR curve... turned upside down. So that it gets louder as it goes lower. Let's please not make this about available information just yet, we all know in car and in music there's supposedly little info below 30Hz... save it, please...I just said it...it's done.

So to most, space is an issue in home. I personally am willing to give up more space in-car than it seems a lot are willing to do in a big house. I have approximately 48" X 32" X 24" external space. That's about 18 cubes before displacement. I am considering both slot port, 3" X 22.5" as long as down one side and the length of the bottom if need be ( about 77" down the center with end correction factored) or an 8" PVC pipe with 1 bend/elbow...I'd have to guess 4" in from side, and 4" up from bottom, and at least 9-10" clearance at the end. ( about 51"?)

I am NOT looking for a "low/loud" 27Hz-33Hz tune! I am not looking for in-room HT response! I am NOT looking for what YOU or joe blo wants! I am asking those who can set aside desired response preferences, and simply help design for the response I want.

THANKS!!!!



So the following copy/paste was a reply from the LLT tutorial, but the LLT tutorial is under the larger slot of Home Theater... and this is car audio, so here is the car audio LLT thread I guess LOL :D

The first scenario describes a typical commercial ported subwoofer or DIY ported subwoofers that were common a handful of years ago - they have some issues. I then go on to explain the benefits and drawbacks of sealed - it has issues as well. I then go on to explain how we can make a sub that sidesteps a lot of these issues. To do it, one has to take a second look at ported, but go ported in a way that isn't and hasn't been very common.

No contradiction, just suspense until the big payoff :T
And I replied:
" Well I think it's my favorite thread.... Now I've got to take the time to read the rest, but I think the 1st post is the most informative and important.

I guess my biggest concern since I first read it a while back, is I'm taking what you say about round ports pretty seriouse. I can see how slot ports, especially rectangular and not square, can cause issues. I don't think very big issues, but none the less I see how round is superior. I have limited space, 48" x 32" x 24" external.... I suppse I could get an 8" port guessing around 50" long, taking up about 2.7 cubes of 18.4 cubes... so we'll over guestimate displacement for 15 cubes, 8" port 50" long...making about a 13Hz tune

Is that enough for an 18"? I'd really like to try to make a 22" work if they come out and look promising.... I know that with Vd like that, an even larger port would be desired...but I'm expecting to rarely reach much output below 30Hz at high levels...if this box were for HT, I could see needing a 10" or 12" port and double the cubes...which I would readily sacrifice in home..... I have limited round port experience, i've done a little, but never with elbows and bends...which Is the part I am worried about.... and 8" is just rediculous HUGE!

Intimidating. "
 

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Discussion Starter #2
3" slot port vs 4"... lose a tiny bit of length and 1 cube with a 4", and i'm thinking it would be much better, closer to the recommended plot with WinISD of I think 13 cubes 17Hz anyway.

Does WinISD factor port compression? If I make a smaller port with high velocity, does it show SPL loss? If I make a much larger cross section with low velocity, does it show better port gain?
 

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WinISD will not account for port/driver compression. It simply assumes (in most cases incorrectly) that both will act in a linear fashion.
 

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Discussion Starter #4
WinISD will not account for port/driver compression. It simply assumes (in most cases incorrectly) that both will act in a linear fashion.
very good to know. I am re-calculating my internal volumes and port lengths (I messed up!) and I'm adding yet another plot to test, 6" port. Basically, no matter what, I will build this thing to full dimensions... but between all of your input and plotting, and more plotting, I will probably keep making the port bigger until I get as close to my desired internal volume and tuning. So if i keep bumping the tuning up and volume down, I should have a very nice cross-section for a port if I go slot.

Maybe I should get a huge 12" PVC..... j/k
 

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Discussion Starter #5
OK, I hope I got it all right this time...if i were good at math i'd be an electrical engineer making my own subs by now ;)

I hope it is, cuz Blaser said he's gonna copy-cat and build one too :no:
 

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Discussion Starter #6
(1) Yellow 6.6 cubes sealed .707 (auto generated by WinISD)
(2) Green 19 cubes sealed largest possible for dimensions
(3) Blue 12.9 cubes 17Hz (auto generated by winISD)
(4) Purple 15.5 cubes 11.85Hz
(5) Red 14.5 cubes 14Hz
(6) White 12.5 cubes 18.5Hz

I PURPOSELY PLACED THE WINDOWS OVER 30Hz ON UP
Cuz for sake of argument, 2 15's sealed is plenty from 30Hz on up...
Now, 4 22's ported low.... I'll still want more sub 30z!
:D
 

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Discussion Starter #7
OK, so I decided to try and tune higher with the 6"... I took off the bottom port board so it only goes down the side, recalced the int volume and port length... the website I use said it was right at 20Hz!!!!! I took that as a sign from the gods.

But as I put the numbers in WinISD, it said it was 22.4Hz or something...and that's not the first time I had conflicting numbers between the website, bass box Pro 6, and WinISD Pro Alpha.
 

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Why? I still can understand this LLt in a car idea, sorry but i really do not see any benefits? Can you explain to me why you want to build a LLT for a car?
 

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Discussion Starter #9
Why? I still can understand this LLt in a car idea, sorry but i really do not see any benefits? Can you explain to me why you want to build a LLT for a car?
I have already done it, if you consider 5.1 cubes @ 19 hz "LLT in-car". I liked it much more than my 3.5 cubes @ 27Hz.
 

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Discussion Starter #11
this stuff was all 3-5 years ago. i'll have to see about putting all my pics in 1 link and all my vids, hopefully where it can automatically be resized, cuz I cant do it with this POS PC
 

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Discussion Starter #12
so the smaller ported for 2 l5 12's didn't show up, that was for friends...built a lot of boxes for other people. the l7 15" was the 3.5 cubes @ 27Hz... my favorite song on that was Soul Survivor Akon and Young Jeezy. Then there's the 4th order bandpass with the 15" Ascendant audio Avalanche had an S factor of .7 and an F3 low of 20Hz. The Lanzar amp blew it with a shut off pop before we had the lid on it... very little experience with that, as the voice coil bottomed hard on the top plate instantly (basically free air) and the coil unwound. Had to cut it open to get the sub out, baught a second one, sealed it off and put another hole in the top converting it to 5.1 cubes ported @ 19Hz

The XX-Colossus is 1 of Pete Hexibase Kuliki's, I bought both, and he ended up selling one to someone else since I didn't call with the cash on time... a day late, but not a dollar short!
 

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