Wall Building Questions: Port Design and Displacement Questions (HELP ME JOE X)

[Doorz1009]

Ok, So I'm in the process of doing a ported wall for 2 RE SX 18 subs, there's still a few things that need done before box building can begin (like welding up the floorboards where some nasty rust has eaten through and replacing the upper suspension) so I have a fair amount of time before the cutting of the wood commenses. The components of the system are as follows: 1995 Saturn SL1, 2 RE Audio SX 18D2, 2 RF T1500.1 bdcp, 2 Pairs of RF P165S Components, 1 RF Punch 400x4, 2 Optima Yellow Top 34/78, Autocraft Gold 75 Group (for the vehicle), and a DB Electrical 220A alt.

The questions I currently have are:

1) Is the amount of airspace I'm shooting for too much/ too little and is my port design properly calculated for the volume

2) Is my idea on how to do the port going to work

3) Being that this will be a build to listen to music on (a wide range of music from metal, to dubstep, to decafs) what would be a good tuning overall being that I love the lows?

First thing is first, I'm shooting for 16 cubes to sorta land in the middle of what the manufacturer reccomends on airspace for a ported enclosure but through looking on forum posts, I've seen that not all manufacturer specs on that are exactly what is correct so to someone who is more wise than I, (HOPEFULLY Joe x can share his expertise) the T/S Parameters are here: http://www.data-bass.com/data?page=driver&id=45

My current design is relatively hard to explain but here it goes. starting at the front of the box, the base of the baffle is 49 inches wide until it hits a height of 23 inches following the shape of the b-pillars up to the roofline where it comes to a final width at the roof of 36 inches and a height overall of 39 inches. This shape can extend back 21.5 inches until the step up to the trunk at which point things get rather difficult to describe. The distance at the top of the step is the same 36 as what is at the top of the box so the piece that goes up the step is 49 at the bottom (where it meets the base of the box) and 36 at the top (where it will meet the back of the box). After going up 7 inches and back 10, the box will go straight up within a small distance of the rear glass, coming to a height of 28.5 inches from the top of the step at which point it travels foreward roughly 7 inches and up 3.5 to the roofline at the same 36 inches wide as what the top of the box is, then the top of the box (obviously) brings this all together. I was figuring about 3 layers of inch thick birch ply, fiberglass all the seams, and a couple 4x4s to brace front to back and bottom to top would make the thing about bullet-proof

The port would be a top-located port, sharing 3 walls with the box creating a trapezoid shaped port. I've found that on average you're looking for a cross-sectional port area of roughly 12-14 inches squared per cube. I'm shooting for right around 16 cubes so the dimensions of the port for 14 sq.in./Cube would be the width of the box at the top 36" by 6" tall and would have a base of approximately 38.5 (38.43 but half is much easier haha) and have a depth of 17.96, roughly 18 inches. This would tune me to 28Hz

My plan to build the port was to have 2x4s mounted to the sides, level and just under the height that the port would be that would run the length of the port to account for the thickness of the board that will be the port and just attach the board to that that would be the depth of the board (and to have pieces of wood underneath running width-wise to brace the port). The reason for this design is that I want to be sure that the tuning is the way I want and to be able to remove a section of the port for adjustment in case the tuning goes awry. My question that I think I know the answer to but truthfully don't is do I take the volume of the box, calculate the port for that, and just displace the air or do I add the volume of the port to the box (i.e. a 2 cube box with a 1 cube port would need to be 3 cubes to make room as opposed to 1 cube air-space and 1 cube of port making a 2 cube box)

Regarding the tuning frequency, I talked to a local shop and they said that tuning to 28 might be too low, that tuning to 30 or 31 would be more practical. And that if I wanted something that could meter and sound good daily that 34 would be a good medium of tuning, which seems awfully high for listening to any sort of decafs or other demo songs. Hopefully I'll get some responses!

[SPL.Pantie.Soak]

I would help if I could man

[Doorz1009]

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