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Sam339
09-11-2011, 12:32 PM
Hey everyone this is my first post here and I was wondering if I could get a couple opinions on my box specs before I start building it. Its for a Alpine type R 12"

W18xH16xD18
2.28ft^3

1.25" PortWidth
14.5" PortHeight
17" PortLength

Thanks!

kushy_dreams
09-11-2011, 04:02 PM
port opening and box volume are too small. The tune comes out to 34.5hz. Is the port length you listed the physical length or did you add an end correction factor to it?

RAM_Designs
09-11-2011, 04:10 PM
Port area is too small. Start off with a larger box so that when you use a larger port you end up with the same final volume that you're wanting.

Sam339
09-11-2011, 05:08 PM
I thought my original box would be to big but maybe not. How about...

W20xH16xD20
2.87ft^3

2.25 PW
14.5 PH
20 PL

RAM_Designs
09-11-2011, 08:10 PM
I thought my original box would be to big but maybe not. How about...

W20xH16xD20
2.87ft^3

2.25 PW
14.5 PH
20 PL

That gives you ~2.25ft^3 with a ~39hz tuning.

kushy_dreams
09-12-2011, 12:21 AM
I thought my original box would be to big but maybe not. How about...

W20xH16xD20
2.87ft^3

2.25 PW
14.5 PH
20 PL

I got closer to 2.4cu/ft tuned to 37-39hz. Keep the same airspace and just lengthen the port to lower the tuning. You will have to keep playing with the dimensions. Type r's like 30-33hz the best. 35hz will work but you are sacrificing low end too much imo.

Team TH (Donny)
09-12-2011, 12:40 AM
I got same as RAM_Designs (you have to consider the # of common port walls). The woofer displacement is .071 cu ft as well, so its net volume is 2.16 cu ft after woofer displacement (not considering a double baffle nor any bracing), tuned at 39.69.. The port area is within reason, but I would go a lower tune if I were you assuming your not going to compete with this setup.

Sam339
09-12-2011, 08:55 AM
May I ask what the heck I am doing wrong. When I enter the dimensions on the 12v calculator its gives me what ive been posting. Sorry for being an annoying newbie.

Sam339
09-12-2011, 01:19 PM
Everything I try gives me a port length that is bigger than the box. The port length is each side of the "L" shape right? Not the entire thing? Thanks alot for your help and input guys. Glad I joined the forums

DukeNut
09-13-2011, 02:04 AM
For W20xH16xD20
2.87ft^3

2.25 PW
14.5 PH
20 PL

use a port length of 34. i get this will yield a net volume of 2.0 cf and tune of 33hz.

To measure total port length, measure down center of each side of port to where the centers intersect and add the 2 together plus 1/2 of the port width(for port end correction). Ram, Kushy, or Team TH correct me if made a mistake.