box build for 4 dc audio xl 18's

[xile]

Hey guys. New here. Looking for a little help on designing a box for my 4 xl 18's. Its going in the back of a 01 suburban. Third row removed. Max width is 46" other than that plenty of room. My thoughts are a 22c.f. net box tuned around 32-35hz. Subs up port back. I've seen a few boxes with a slot port on the bottom I'd like to do a rectangle port mid box. Any thoughts on tuning and size or any ideas in general would be greatly appreciated. This is my first big build and want to do it right. Looking for a good daily sound with still being able to compete possibly. Power will be a dc 9k at 1ohm.

Thanks. Bigjohn

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[Massive spl]

Why is your width 46"??? My 2002 Tahoe has 50" Inbetween the wheel well

Best score I got 4 18s on 8k was 153db. Sub up port back... Box was 22cubes with 180"-200" of port... I had a removable port and tried from 160"-400" of port and 180"-200 was the sweet spot tuned to 32hz

 

[xile]

Im mounting my amp in the rear so im leaving a couple inches for power runs to the amp

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[xile]

Why is your width 46"??? My 2002 Tahoe has 50" Inbetween the wheel well
Best score I got 4 18s on 8k was 153db. Sub up port back... Box was 22cubes with 180"-200" of port... I had a removable port and tried from 160"-400" of port and 180"-200 was the sweet spot tuned to 32hz

Got any pictures of the box. Would definitely like to see the removable port

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[Massive spl]

Im mounting my amp in the rear so im leaving a couple inches for power runs to the amp
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I had my amp under my rear seat

 

[xile]

I had my amp under my rear seat

I got buckets in the second row. Cant fit that big basterd there[emoji4]

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[Massive spl]

A few different boxes... The shorter I made the box the louder it got. I ended up at 22" tall box.. I wouldn't go any taller then 22"

 

[xile]

Thats exactly what I envisioned for a port. Looks good.

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[xile]

A few different boxes... The shorter I made the box the louder it got. I ended up at 22" tall box.. I wouldn't go any taller then 22"

All 3/4 mdf with a double baffle?

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[Massive spl]

Birch... Fvck mdf. And yes 2-3 layers and braced like a mofo

 

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Birch... Fvck mdf. And yes 2-3 layers and braced like a mofo

Gotcha. Couldn't tell on my phone.

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[xile]

Did you trim the inside of the port or is that bracing in the pic

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[Papermaker85 5,000+ posts]

Birch... Fvck mdf. And yes 2-3 layers and braced like a mofo

i know i know i'm not trying to beat you up, but i did some re-search today and hickory pecan and white oak stronger than birch.. its just to find them in anything but veneer and with soft cores..

also i agree with the lower profile. wider and deeper and no higher that back seat tends to work best. otherwise its start to sound trapped in the rear. im assuming its reshaping the transfer function acting almost as two separate variables(two cabins so to speak)?.. which brings me to this article.

http://www.rug.nl/research/portal/files/2907090/c6.pdf

that is why i recommend people get a sealed box with a critically damped alignment and run a few sweeps before and after the initial install and better help map the transfer function and any obstructions.

port up; port back; sub back; subs facing forwards; box shape and profile all affect transfer function..

 

[Massive spl]

i know i know i'm not trying to beat you up, but i did some re-search today and hickory pecan and white oak stronger than birch.. its just to find them in anything but veneer and with soft cores..also i agree with the lower profile. wider and deeper and no higher that back seat tends to work best. otherwise its start to sound trapped in the rear. im assuming its reshaping the transfer function acting almost as two separate variables(two cabins so to speak)?.. which brings me to this article.

http://www.rug.nl/research/portal/files/2907090/c6.pdf

that is why i recommend people get a sealed box with a critically damped alignment and run a few sweeps before and after the initial install and better help map the transfer function and any obstructions.

port up port back sub back subs facing forwards box shape and profile all affect transfer function..

Yea but the birch is $42 a sheet at menards/Home Depot.. Those hickey and white oak prly cost arm and leg

 

[Papermaker85 5,000+ posts]

Yea but the birch is $42 a sheet at menards/Home Depot.. Those hickey and white oak prly cost arm and leg

http://www.workshoppages.com/ws/misc/wood-hardness-chart.pdf

Columbia Forest Products 3/4 in. x 4 ft. x 8 ft. Purebond Maple Plywood-263012 - The Home Depot

both are 50 bucks here.. none of them have really really hard cores. makes me wonder if stacking 2 1/2" sheets would be alot stronger than 1 which typically isnt the case but might be strictly because of the narrower cores in the 1/2".

nearly everywhere i called only had veneer and thats just two "skins" with a soft core..

i felt like a idiot on the phone with a local highend wood shop..

"we have a b2 beech veneer" i'm like i want the hardest **** *****. i gotta beat the block.. "excuse me?"