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Blu84Rex
01-31-2007, 09:29 PM
I am trying to figure out the math and I am getting stuck on the port length & tunning on a box for 2 12" type r's.

Outside measurements are 40" wide, 15" High, 15" deep.
Which brings the gross volume to 4.06ft^3 and after driver displacement 3.91ft^3.

The local stereo guy says that the port measurements should be
13.5" high
2.75" wide
15" deep

That would tune to 38hz
I would like to tune somewhere closer to 33hz. What would the length of the port have to be for that?
I also have a couple of math questions. How do I find out the displacement of the port and how do I measure the port? do I start from the outter face of the box and stop 2.75" from the back and start from the side and go over the remaining distance.

DBfan187
01-31-2007, 09:32 PM
Let me see here... I'm getting 33.3333 repeating of course.

Blu84Rex
02-01-2007, 11:57 AM
Huh??

phyphoestilic
02-01-2007, 12:00 PM
ur port length needs to be 33.33 inches to tune to 33hz

DBfan187
02-01-2007, 12:04 PM
Let me see here... I'm getting 33.3333 repeating of course.LEEEEEEEEERRRRRRRRRROOOOOOOYYYYYYY JEEEEEEEEEEEEEEEEEEEENNNNKKKKKKKKINNNNNNNNNNSSSSSS

POLKAT
02-01-2007, 12:05 PM
Let me see here... I'm getting 33.3333 repeating of course.

Leeroy Jenkins? ;)

Sorry, but you have me on the math. I could prollly figure it out but I feel too lazy. A much easier thing to do is to click here: http://www.caraudio.com/forum/showthread.php?t=137804
and choose one of Moe Lester's stickied box plans. Scroll down to the ones that are 4 cu ft @ 33 hz or so and pic one.

edit: I guess some of the designs have broken links now.

phyphoestilic
02-01-2007, 12:06 PM
LEEEEEEEEERRRRRRRRRROOOOOOOYYYYYYY JEEEEEEEEEEEEEEEEEEEENNNNKKKKKKKKINNNNNNNNNNSSSSSS

lol funny video. "Leroy u fu*ken as$hole"

rpfuror
02-01-2007, 03:46 PM
Let me see here... I'm getting 33.3333 repeating of course.

ummm...

33" = 29.50 Hz on my calc.

23" = 32.90 Hz on my calc.

did you mis type?

DBfan187
02-01-2007, 04:46 PM
ummm...

33" = 29.50 Hz on my calc.

23" = 32.90 Hz on my calc.

did you mis type?http://www.youtube.com/watch?v=Zll_jAKvarw

Blu84Rex
02-03-2007, 10:14 PM
I came up with 23" also for 33 hz but when I do it on carstereo.com (http://www.carstereo.com/help/Articles.cfm?id=31) i get 17.5" IS my math wrong? I would also Like to have the port in the center of the box . How would I go about that, would it have to be a T shape and how would I measure a T port ? The same as an L from center to center or different? Or would it just be better to have it on the side.