Box tuning?

[germanyt]

I know this question has been asked before but I'm looking for a website that gives accurate port dimensions. Also, how to you measure the port? LxWxH? I need to figure out the port dimensions for 31Hz in ~8 cubes. Width is about 37", height is about 17", and depth about 26". It's about half MDF and half glass so figuring out the exact volume is difficult since the box cannot come out of the car. Thanks for any help.

[germanyt]

I found a page on caraudio.com. I hope its accurate.

[CBFryman]

WinISD is as actuate as you will need.

[bumpinstang77]

8 cubes net after all displacements including driver and port? If so go as follows.

6 3" ports 12.6" long each
8 3" ports 17.5" long each
10 3" ports 22.5" long each
12 3" ports 27.4" long each
4 4" ports 14.6" long each
6 4" ports 23.4" long each
8 4" ports 32.2" long each
10 4" ports 41.0" long each

[germanyt]

Where did that info come from? Also, how about slot ports. A single 16" x 4". What would the depth be for 31 Hz for 7, 7.5, and 8 cubes, excluding driver and port displacement (exact volume is still undetermined)?

[germanyt]

make that 15 inch tall x 4 inch wide

[germanyt]

Originally Posted by bumpinstang77

8 cubes net after all displacements including driver and port? If so go as follows.

6 3" ports 12.6" long each
8 3" ports 17.5" long each
10 3" ports 22.5" long each
12 3" ports 27.4" long each
4 4" ports 14.6" long each
6 4" ports 23.4" long each
8 4" ports 32.2" long each
10 4" ports 41.0" long each

Also, I'm not sure I understand how you did this figuring in port displacement. Let's say my box is 7.5 cubes. The driver displacement is .36 cubes. So I'm at 7.14 cubes. To tune a 7.14 cube box to 31 Hz requires a certain size port. So I use 7.14 cube port dimensions. If port displacement needs to be accounted for, my 31 Hz port has changed my box from 7.14 cubes to roughly 6.5 cubes. Since the enclosure is smaller due to displacement, the port size is now not correct because it was calculated based on a 7.14 cube box. Should I just assume that the box will be roughly 6.5 cubes with port and driver displacement and port based on that volume? If I tune based on 7.14 but port displacement makes it ~6.5 then my tuning freq changes from 31 Hz to about 29.6 Hz. How much would 1.4 Hz change the sound? And does this post make sense? Sorry if it doesn't.

[germanyt]

somebody plz help quickly, i have to get these dimesions tonite. ng, fry, stang, where ya at?

[germanyt]

things have changed, its actually 6.64 cubes without displacement so ill have to figure that out. should i tune higher to make up for lack of volume or staple cotton to the inside of the box?

[germanyt]

well, the decision was made. since the subs are only 2 inches apart and there isn't much room above or beneath them, a slot port was pretty much ruled out. my favorite next to the slot was 6 3 inch ports 16.74 inches deep. three on top and bottom in a triangle patter low and upside down triangle high. the other option, to reduce port displacement as much as possible is two 4 inch ports, 8.3 inches deep or even 2 3.5 inch ports 6.03 inches deep. they seem awful small but i guess that is how it works.

[bumpinstang77]

COMPLETELY stuff that bitch with as much polyfill as you can get in it without Blocking the polevents and ports to get them up closer to 8 cubes NET.

[CBFryman]

doesnt work that way with ported enclsoures.

[OffRoadSonoma]

So are you saying polyfill doesn't work in ported boxes CB?

[bumpinstang77]

yes it does dipshit. It slows down the waves hence making the box sem bigger. My AV18's box changed when I just lined it with polyfill. It makes the box seem bigger, lowers the tuning, and helps the low end out a little bit.

[germanyt]

does it matter how large the port is as long as it is still the right tuning freq? what i mean is, a 6 inch long port seems awfully small will it still work the same as a larger port of the same freq?