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MikeMartel

18" BTL N2 Box Design

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I'm not talking about an abnormally huge port, I'm talking about the minimum port area to be used when designing a port for a certain woofer. Do that, and you'll have a properly functioning vent, which can be used in the SPL lanes, and in SQ judging.

Right, I think we meant the same thing, but worded differently. I see a 20 square per cube port too large and wouldn't sound as good as a 10 square per cube. And I definitely agree that enclosure size is the biggest thing when it comes to controlling a sub mechanically.

Doesn't the subwoofer parameters have to do with how much port to use and power being applied? I've kinda lost it... but maybe I missed a posed that stated that... :ughdunno:

I just think that if that's what he's set on then let it rip. I'm not gonna blow on the coals and re-ignite this one.

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Im not 100% set, Ill always change something if its not going to be proper.

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..amount of power applied should correlate with box size..bigger doesn't always mean better or louder..

That's what she said. ;)

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Legendary Demin...

Nick left it out there. ;)

But on a serious note, it is totally ok for a serious technical argument, but can we please keep it civil and relax on the name slinging?

- your friendly admin. ;)

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Well I found this thread informal at least.. The first time I tried aeros I did it on a 21" warden and the psp-inc website doesn't give recommendations based on woofer specs just on the enclosure. Needless to say.. I don't design or build my own enclosures.. I do try to map them out on free programs. But the shop I go to for this has much better tools at hand. I buy what I want to use and they do the rest.... Even if it's not what I wanted them to do...

I do want to see the results of this build though. I want to do an 18" and I'm trying to decide on the N2, Xl, or XXX on 3k with about 6-7 cuft...

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Well, Blak right now Iv got my BTL on only 1500wrms in about a 5.5cuft box in my car right now. Sefugi made a link to my build log. And to be honest it sounds awesome, the main reason im building this new box is to fire it into the cabin. Id 100% buy the N2.

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Alright, iv got a few minor changes to my box once iv got into the details. But this SHOULD be perfect. This time iv done all the calculations and havent used an actual box builder, so hopefully its right.

In order to make it fit a bit easier, I pulled down the volume a bit, along with a little less port area.

Width = 36"

Depth = 36.4"

Height = 15"

Gross Internal Volume = 9.4 cubic feet

Port Width = 8"

Port Length = 15"

Port Length = 33.07"

Port Displacement = 1.72 cubic feet

Subwoofer Displacement = 0.18 cubic feet

Net Internal Volume = 7.5 cubic feet

Tuning = 32

HOPEFULLY this is right, if it is, i really think iv got this box building stuff down. :D

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Hate to say this but actually that volume on the port is likely a bit off unless you've already calculated for the thickness of the boards that are going to be making up the port walls. It's not too hard to figure, but they have to be included in the calculation in order for the volume to be totally accurate.

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Hate to say this but actually that volume on the port is likely a bit off unless you've already calculated for the thickness of the boards that are going to be making up the port walls. It's not too hard to figure, but they have to be included in the calculation in order for the volume to be totally accurate.

Yeah you are off a bit.

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Alright, iv got a few minor changes to my box once iv got into the details. But this SHOULD be perfect. This time iv done all the calculations and havent used an actual box builder, so hopefully its right.

In order to make it fit a bit easier, I pulled down the volume a bit, along with a little less port area.

Width = 36"

Depth = 36.4"

Height = 15"

Gross Internal Volume = 9.4 cubic feet

Port Width = 8"

Port Length = 15"

Port Length = 33.07"

Port Displacement = 1.72 cubic feet

Subwoofer Displacement = 0.18 cubic feet

Net Internal Volume = 7.5 cubic feet

Tuning = 32

HOPEFULLY this is right, if it is, i really think iv got this box building stuff down. :D

Aside from what Alton and Rick said about port wall thickness, your port is partially external, meaning only part of it affects the enclosure volume, with the information you listed we have no idea how much of the port is inside the enclosure and how much is outside.

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Oh yes... Well back to the drawing board then. Gotta add in the wood thickness.. But only 8.25" of the port is external, So about 24.75" is internal. Let me try this again.

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Alrighty, So NEW Port and Subwoofer displacement is 2.493 cubic feet.

Which means ill need my box with the dimensions of 36w x 38.6L x 15h = 9.999 cubic feet, which will bring me back to 7.5 cubic feet net, same tuning, and we are good to go. :D

Correct? If im still wrong, somebody help me out here. I think iv got the basic idea down and i actually understand what im doing (hopefully). Thank you Stefan for your port tuning calulator, and thanks Alton for your calculator aswell, it gave me a great knowledge and understanding about how everything works and hopefully ill be designing my boxes all on my own soon enough.

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Would have did around 6 - 6.5 cubes for a single. Depending on power, what will you have powering it?

Edited by YojO

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Would have did around 6 - 6.5 cubes for a single. Depending on power, what will you have powering it?

-American Bass VFL 100.1 (Powering Sub)

its in his sig

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Sorry didn't see that LOL. Well it should slam pretty D*** good.

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