anyone want to check my math?

[waltham415 0]

So i have decided to build a custom box for my 2 10in type-s alpine subs. I found an equation on JL audio's website to tune a box and have been playing with numbers for about an hour now. Everything looks good to me i just want to have someone double-check to make sure im not screwing things up.

The outside dimensions of the box are 11.5X31.5X20.5in. Using 3/4in mdf that would leave me with 5700 cub inches inside to work with. there will be a single vent, 10in tall and 1in wide, going in 5.5 inches. after subtracting the volume of the 2 boards used to create the vent and the 2 subs( 86.4cu in each), ill be left with roughly 5444cu in of internal volume. with the equation i found that would leave the box tuned to 32.5 hz. .5 hz off of my goal

Does that sound about right? the main reason im worried is that i thought the longer the vent, the lower the tuning, so a 5.5in vent seems really short to me. i dont know.... any comments are appreciated as i really want to get this right. Also... does anyone think i will need bracing for these subs? im running 500wrms between the two, so not too much power, but just to be safe?

[bigrank916 72]

If Im reading this correctly, the enclosure youd like to build has the dimensions of 31.5W x 11.5H x 20.5D? If so that would be 3.3cuft to start with. These dimensions will be too small and this is why...

The two boards used for the port cant be the same size. One is 18"x10" and the other is 5.5"x10". So the figure of 86.4 cuin each isnt accurate. You are also forgetting about driver and port displacement. That will take up additional internal volume. This enclosures dimensions must be larger. Is that the max size you can go?

I wouldnt do bracing for those subs as it will just be extra work that isnt really needed.

[KU40 173]

You will need more port area. Make the port at least 2" wide. Also, if you use one side of the enclosure as one side of the port, port displacement uses up less internal volume.

[bigrank916 72]

You will need more port area. Make the port at least 2" wide. Also, if you use one side of the enclosure as one side of the port, port displacement uses up less internal volume.

At least. He will have to refigure that box totally to get the right tuning and such. Its also more work making two ports.

[shizzzon 461]

when i get home, i'll check the math

[shizzzon 461]

I'd have to draw it out, but make port 3" wide, the port will drive all the way down the depth of the box and will turn and go down another wall by just a couple inches.

[Don Ganso 13]

Agree with everyone here. That first port was way too small. Did you find out what the driver displacement was?

[waltham415 0]

Sorry for the delayed responce. so i have plenty more room in my trunk, mainly in depth and height, not so much in width though(too much bigger though and im not sure ill be able to get it inside my trunk). the driver displacement was, according to the sight, .050 cu ft.

So by the sounds of it i am way off on just about everything so any help i can get would be appreciated, like i said i would like the box tuned to about 30-32hz and could care less about how much space it takes up in my trunk. any ideas, dimensions, formulas, ect would be cool. thanks

Just as a reminder im running 2 10in alpine type-s subs ran at 2 ohms with about 250wrms being ran into each by an alpine mrp-m500(not sure if it matters)

[NB50 206]

2.32ft^3 @ ~31hz

[bigrank916 72]

What software did you use to make that?

[NB50 206]

Calculations done by a spreadsheet I made then drawn up in sketch up.

[waltham415 0]

Wow, thats a cool program you have, and that box looks relativly easy to build also. being that its tuned just how i want it and i think it will be able to slide into my trunk, i think ill build it like that. Thanks for the help everyone