do these specs from RE calculator sound right

[pablo4429 10+ year member]

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

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[Atimm693 10+ year member]

I didnt do any calculating but from what ive heard and tried RE calculator is off some.

 

[pablo4429 10+ year member]

i wonder by how much?

 

[Atimm693 10+ year member]

I did it once and IIRC it was off by like 2 inches.

 

[pablo4429 10+ year member]

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 10+ year member]

use the formula in my sig....you can't go wrong....

 

[pablo4429 10+ year member]

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 10+ year member]

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.