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View Full Version : do these specs from RE calculator sound right



pablo4429
02-25-2008, 09:52 PM
23"wide x 18 tall x 15 top depth and 17 bottom depth
port width 1.75
port length 13.5
tuning 30.15hz
port area 28.875
volume 2.458 (which will be smaller because of woofer and bracing.)

so does all that sound correct just to make sure before i build it
thanks a lot all

Atimm693
02-25-2008, 10:48 PM
I didnt do any calculating but from what ive heard and tried RE calculator is off some.

pablo4429
02-25-2008, 11:12 PM
i wonder by how much?

Atimm693
02-26-2008, 09:28 AM
I did it once and IIRC it was off by like 2 inches.

pablo4429
02-26-2008, 12:21 PM
ok that is pretty off so how do i calculate how much port area I need so I can use WINISD and the sticky?

Trixter
02-26-2008, 02:25 PM
use the formula in my sig....you can't go wrong....

pablo4429
02-26-2008, 10:20 PM
trixter


Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
*Vb = vol. in cu"
**R = sq.rt. A / Pi

what does Vb stand for
and what does Fb stand for and how do i calc it
and just to clarify R=(Area of port/Pi)^.5
if A is area of port how do I know how big to make it???
sorry for all he questions but i havent found a tutorial yet that explains how to do all the calculations

Trixter
02-27-2008, 10:25 AM
trixter


Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
*Vb = vol. in cu"
**R = sq.rt. A / Pi

what does Vb stand for
and what does Fb stand for and how do i calc it
and just to clarify R=(Area of port/Pi)^.5
if A is area of port how do I know how big to make it???
sorry for all he questions but i havent found a tutorial yet that explains how to do all the calculations

Vb is the box internal volume in cubic inches
Fb is the desired frequecy
R in the formula is the Radius of the port. but if using a square / slot port, then R = the square root of the area divided by 3.14.

The area of the port should be determined by the mfg's specs.
you can also use a genaral rule of 12-18 sq" of port per cubic foot of air space.

once you have the numbers, simply plug them in and do the math.