help with box please

[gotb00st 0]

Hello, 

 

This is my first time building a box. I would like to hear any thoughts you might have before I get to building.  I just recently purchased 2x FI Q 12's dual 1's with cooling, and spider. I designed a box for a 2002 gmc envoy. These subs will be pushed by a Crescendo BC2000D. (May eventually upgrade to a 3500 or 2x 2000's).  Box is 5.0 cu ft and is tuned around 32hz. 

 

Heres what I came up with.

 

 

 

 

 

My main concern is if I did the port length correctly and if I calculated the bracing displacement correctly. 

[gotb00st 0]

26 views no replies. Can anyone help?

[altoncustomtech 773]

I've not had a chance to do all the numbers yet, but just from what I see on the intended port length and the measurements you have on the drawing the port is too short.

Here after a few I can get my laptop out and plug thru the numbers to verify everything else.

[gotb00st 0]

I've not had a chance to do all the numbers yet, but just from what I see on the intended port length and the measurements you have on the drawing the port is too short.

Here after a few I can get my laptop out and plug thru the numbers to verify everything else.

Ok I'm confused as far as the port length goes. I calculated it by adding the measurements of the middle of the port counting both L ports and including the middle bracing in the measurement.

[altoncustomtech 773]

The basic rule (and I really HATE using the word RULE) for doing a split center port like that is the port length plus half the width on each split and the splits are 1/2 the actual port width.  So say the port length is supposed to be 20" long and the port width is 4".  The total port length when you get then the end of the port in each chamber should be 22".  You're showing 16.75" on the first port wall, plus 1.25" (as it does look like your splits are 1/2" the 5" total port width), plus 2.5" from the center of the center part of the port, plus the 6 1/32" of the split port length equals 26 19/32" total length.  Your port length according to the Torres calc should be 26.75, so the length you have is fine for a standard slot port, but it needs another 2.5" to be closer to right for the split center port.

 

 

Other than that your drawings are great, you've done really good on them.  The rest of the calculations are looking alright from what I can quickly figure.  It will take me a fair bit more time to break everything completely down to check the numbers down the the level to know that the volumes are right on and things.

[gotb00st 0]

That makes sense. im looking to start this build this weekend. so basically I need to add approx. 2.5" to the l port on each chamber?

[gotb00st 0]

also originally I was going to do a basic L port design but I was told I would have unloading issues and would need more bracing.

Edited February 20, 2013 by gotb00st

[gotb00st 0]

I redid the box and fixed the port. Does this look correct now?