Port Length/tuning-help Wanted

[andym85]

wat dis mean ^ n this *

Lv = Av*1.84*10^8/[Vb*1728*(Fb/0.159)^2] - 0.823*sqrt(Av)

that is the formula to find your tuning frequency

Fb = tuning frequency

Av = vent area

Vb = net volume in cubic inches

Lv = effective length of vent

effective length = physical length + end correction <---1/2 of the ports width

[had001]

that is the formula to find your tuning frequency

Fb = tuning frequency

Av = vent area

Vb = net volume in cubic inches

Lv = effective length of vent

effective length = physical length + end correction <---1/2 of the ports width

but wat does * ,^, mean?

[andym85]

* = multiply

^ = raised to the power of

[had001]

i think i finally figured out my port lenght. 16.5x3x10, it comes to 39ish Hz. am i right or wrong

[andym85]

what are the dimensions of your box? 18*40*18?? if so, then yea, 39is is pretty close

Edited April 11, 2007 by amatt85

[had001]

what are the dimensions of your box? 18*40*18?? if so, then yea, 39is is pretty close

The gross dimensions is 17.25x40.75x16.75.

the net dimensions is 16.5x40x16.

M i still close or back to the drawing board again

[had001]

is that for just one port for the whole box or both ports??????

[andym85]

The gross dimensions is 17.25x40.75x16.75.

the net dimensions is 16.5x40x16.

M i still close or back to the drawing board again

if the inner dimensions are 16.5*40*16, then the outer are gonna be 18*41.5*17.5 (if you are using 3/4" mdf)...you gotta add 1.5" to each dimension to get your outer, not just .75".

so i put your inner dimensions at 16.5*38.5*16.5 for the box and got a tuning of about 38ish and a net volume of 5.765cubes (which includes displacement for the port and for the subs, i used .15cft for each sub which was just a guess)

[had001]

I think i finally got. Can some one please check my measurements if there right. The box is suppose to be tuned to 39-40ish hz. M i right or wrong?