more bracing needed?

[Gavin]

Steve,

I posted this same question to my team mates over at Maxxsonics, but I would like your advice also.

I got 8 weeks to get my car ready for the Japan finals! So far, here are the pics of the box I had to modify. It went from a 6th.order to a 4th.order.

 

Now, here is my problem. the "top" part measures

W=31.5"

H= 9.5"

D= 49.75"

Question, do I try to build a port for the top part, or just leave it open as one big port, and flare the edges? The box is for all out SPL ONLY! holding 2 APX 18D2's..

also, the box has been resined, but not sure if I need more bracing? in the bottom area. Once the box is in the car, the outter walls will be lined with 2x4's all around.

any advice??  =V^

[RichardXTC]

A Lil extra bracing never hurts... try getting some threaded bar and brace from the top to the bottom and side to side... should help with making the box stop flexing... just curious have you tested yet?

[Gavin]

:V No test yet.. still trying to round out the corners in the port. today I tried using some triangled pieces sealed over with resin. Once the corners are somewhat rounded, the testing will begin. :^

[RichardXTC]

well you could cut a rise into quarters and use that... well good luck with it and keep us posted with the reading... 

[Gavin]

Well, today started out  :^, got up early and did some sanding, resined the corners, all looked well until I tried to put the sub in the box , and it would not fit!! for  the life of me I could not figure out why, then it hit me like a ton of bricks!! I braced the wrong side!!  The area I was working so hard in was the sealed area! So I had to remove all the bracing, and start to sand an get the opposite area ready.  After a few hours of sanding, I did a sub test and again was upset :'(, The baffle board was place so low that the sub was resting on the box floor! There was NO space under the magnet.  Panic, anger and just a feeling of f**k it came over me, 7 hours of work and no happy result :V :-[ :'(

Well, time to cowboy up and try to repair this  newbie mistake (note: MEASURE YOUR S**T!) After reading about how steve had to do a break down on one of his almost if not completed projects, I figure, if steve can do it. SO CAN I :^ To raise the subs a few inches off the box floor, I'll create some basics spacers, about 2 rings high, it should be easy using my Jasper jig model 200. I wanted to add at least 2 more 1" sheets of MDF to the baffel board, but due to the resin and side braces, I can't, but for bracing, I'll use some all thread   Question is where to put them? Do I all thread the top port and the bottom port?

P.S. If I did not explain things correctly, just take a look at the box.. the wood braces should be up top, the box is upside down >

holla back when you can youngin

[Ernesto]

Raise it up how ever high you need and fiberglass it to give it good bracing. Kinda like what did Steve with the Navigator build up.

What kind of ports are/will you be using?

[Gavin]

Raise it up how ever high you need and fiberglass it to give it good bracing. Kinda like what did Steve with the Navigator build up.

What kind of ports are/will you be using?

Righ now, I have no Idea on port size, I was thinking of just leaving it the way it is, The longest port I can make is only 13" long before the port starts to cover the woofer cone

any suggestions

My port play area is

H=12.5"

W=31.5"

D=13"

[RichardXTC]

WEll do you have a desired frequency? there are equations to use to find the frequency of your current port dimensions or even to work out new dimensions with your own desired frequency... i dunno about bracing the port tho... wont that reduce the port volume which might change the frequency?

[Gavin]

WEll do you have a desired frequency? there are equations to use to find the frequency of your current port dimensions or even to work out new dimensions with your own desired frequency... i dunno about bracing the port tho... wont that reduce the port volume which might change the frequency?

Bro, I would like to know the equations to figure out my port freq now ;D I have no Idea what it will do!

[RichardXTC]

Ok heres the website link where i learned the equations http://www.diysubwoofers.org/misc/portcal.htm