Concrete SPL build

[keep_hope_alive Premium Member]

It's on.

ordered a Fi BL18 dual 2 ohm sub the other day. we considered the SP4 18 but the sensitivity is so poor, with our power we need an efficient sub. The Fi BTL N2 was our desire but the budget needs to be realistic (after the purchase i did see one for sale on here for $450 which we would have done). The BL18 should achieve the desired goals given the Massive N4 power.

will be concrete, thickness to be determined. i have 14 cu. ft. to work with (max external dimensions). with 3" thick walls all the way around (incl forms) that leaves 7 cu. ft. before port displacement.

i started a computer model of the vehicle in EASE. i will use it to model sound propagation and interference patterns at harmonics of the desired fundamental (100Hz low limit on calcs).

I'll design the layout in CAD ahead of time. goal is for a competed project in December.

 

[keep_hope_alive Premium Member]

the suspension has already been beefed up for hauling/towing so we don't have to worry about that right yet.

 

[THATpurpleKUSH 5,000+ posts]

I cant wait to see the finished results!

 

[Spooney 10+ year member]

In for the build and results. Gonna be awesome.

 

[keep_hope_alive Premium Member]

I will start a build log in the right section when we start pulling interior.

Anyone got a preference in the concrete mis used? I assume fine and not coarse.

 

[CAT MAN 5,000+ posts]

use coarse for a texture look. would be cool

 

[snoopdan 5,000+ posts]

concrete setups are usually non-driveable after the fact. Just sayn'

 

[stevew007 10+ year member]

the suspension has already been beefed up for hauling/towing so we don't have to worry about that right yet.

so what was done to the suspension? i had a 94 with the fiberglass mono leaf and it ****** for weight.the guy who bought it from me did bags and ended up busting the bag and rear leaf. I also hear that he had broke a control arm or a-arm off the frame and has been welded 3 times.now the van is too dangerous to drive.

also why concrete?why not steel structure lined with mdf or something? are you lining the concrete with anything like mdf? are you planning for just plain smooth concrete? how are you going to pour the concrete on the top of the box? the last extreme box i worked on had a back wall that was 10" thick the floor was 4"+ sides were 5".concrete is a lot of weight and dangerous as all hell to drive around with it.any upgraded brakes on the van?

I think someone is over thinking this build myself.but what ever i helped build one extreme vehicle and it was a total blast. but when it came to making change's like moving the back wall 5" hahaha i told him i was sick.

 

[keep_hope_alive Premium Member]

Thanks for the feedback. OSB will be used for the forms, a box within a box will be built. Making the face is the next challenge in my plan right now, the front may be a separate piece. I can put fasteners in the box pour.

Concrete is being used for mass, rigidity, and strength, as well as transmission loss. May only end up with 1.5" of concrete if we use 3/4" OSB. OSB is being used for obvious reasons (if you are familiar with concrete forms).

It appears the suspension upgrades includes upgraded leaf springs and frame work. It is a truck frame, which helps.

Through CAD I will be able to determine the cu. ft. of concrete in the design and thus the weight.

I am considering just making the back, inside, and front with concrete and let the top, bottom, and outside be reinforced wood to keep weight more centered and lower. We'll see.

Safety is a huge concern. A reinforced floor and roof will be required, welding is inevitable and not a hindrance. I have to determine forces and sheer strength of fasteners as well. I will be consulting with some of the structural engineers in my firm to verify my calcs. I will be approaching this with a very conservative mindset. No sacrifices will be made in relation to safety. I don't want to build something that will move in an accident.

 

[mlstrass 5,000+ posts]

Concrete enclosure seems like extreme overkill for those subs off that power level.

Being a C pillar wall extreme SPL can't be the main purpose, so why not make it easier on yourself. Unless you're just wanting to have some fun with cement.

Either way GL with the build...

 

[keep_hope_alive Premium Member]

Concrete enclosure seems like extreme overkill for those subs off that power level.
Being a C pillar wall extreme SPL can't be the main purpose, so why not make it easier on yourself. Unless you're just wanting to have some fun with cement.

Either way GL with the build...

i don't think it's overkill for proper control of the rear wave to prevent cancellation through the enclosure walls.

mostly fun with concrete. something i've wanted to try, and i have a platform to try it on. materials are cheap. we may likely fab a standard enclosure while we build the big one.

 

[Wanacustomx 10+ year member]

damnit it was my btl18 i needed to sell that thing man!!!!!

 

[Kadori 10+ year member]

But we live near Iowa, so if it can haul six Iowans around, it can haul some concrete...

being an iowan, i lol'd

 

[SourDeez 10+ year member]

Cement? Thats for sidewalks.