ATTN: Box Designers. Please Check my work

[rickmandick]

Box Length 30

Box Height 19

Box Depth 19

LxWxH=10,830

10,830 x .77 = 8339.1 Gross Internal

8339.1 x .82 = 638.062

638.062 / 1728 = 3.96 Net Internal

Now if i want roughly 65 inches of square port, a port width of 3.75 and a tuning of roughly 35hz, my cut sheet looks like this. Please tell me how far Im off. I havent done this in 8 years, but according to my math, Im right where I need to be. This if for port and sub front facing, with an L shaped port.

Top: 30 x 19

Bottom: 30 x 19

Back: 28.5 x 17.5

Front 25.5 x 17.5

Right: 19 x 17.5

Left 19 x 17.5

Side Port: 13.75 x 17.5

Back Wall Port 3.75 x 17.5

Like I said before, shooting for 35-36 hz

[Joe X]

You are off somewhat, 4.08 [email protected] BUT that's without accounting for driver displacement, you will end up with lower net and higher tuning after installing the sub. don't know where those 0.77 and 0.82 numbers come from, some magic numbers?

Make you life easier and download Torres calculator from this site.

[rickmandick]

.77 is the number recommended by DD for enclosures under 5 cubes to get gross internal. It really should be .75, but that falls under the 10%.

.82 is the number recommended by DD to include subwoofer, bracing and port displacement.

These numbers do not appear "magic" at all. DD came up with them after running calculations for enclosure's under 5 cubes all while taking into account the average sub, bracing and port displacement.

At this net size DD recommends, 64 sq of port and 19 inches in length for a tuning for 35-40hz.

I've used Torres and everything else the past few days. Not much help with DD's limited available T/s numbers and none seem to work for a L port.

[Joe X]

Ok the numbers come from DD, those are estimates at best, Torres asks for no T/S parameters, basically the calculator will let you forget about crunching numbers and focus on what needs to be done like where to aim and locate sub and port.. etc.. Here is a shot of the calculator set at the measurements you have provided:

The driver displacement I used is for a DD 2515 but you can change it to whatever you are working with.

[rickmandick]

I messed up bad now. I went and purchased craft board today and made a box to those dimensions, they didnt work.

New Dimensions are 33 x 18 x 18.

I even cut all the wood.

Now it looks like Im way off on tuning.

Here is what I already cut.

Top: 33 x 18

Bottom: 33 x 18

Back: 31.5 x 16.5

Front 27.50 x 16.5

Right: 18 x 16.5

Left 18 x 16.5

Side Port: 13.25 x 16.5

Back Wall Port 8.75 x 16.5

Like I said before, shooting for 35-36 hz

4 inch port width

In case it matter's the sub is a DD 9515

It doesnt look like I can get to 35-40 hertz without losing alot of box size

According to torres, I need to recut the front and the ports, but I cant figure out the length or cuts to get it close to 35- 40 hz.

[rickmandick]

Am I wrong to think that if I recut the front and ports using these measurements and displacement of .2 with a port with of 3.5 i end up around 35hz? Front 27.25 x 16.5

P1 13.75 x 16.5

P2 10 x 16.5