Designing a ported box with George

[Thuracine187 10+ year member]

*bump* for some help

 

[Nikuk 5,000+ posts]

what do you want to tune it to?

=0.159*(((AV*(1.84*10^8))/((Vb*1728)*(Lv + 0.823*(Lv^0.5))))^0.5)

 

[jellyfish420 10+ year member]

assuming the 18.5 and the 16.5 are internal as well....you never said what you wanted it tuned at but 15" long would be 30Hz. and the higher up you go (tuning)would only make the port shorter.

 

[Thuracine187 10+ year member]

opps didnt relize i didnt say what to tune it to

i want to tune it to 33hz sorry bout that and thanks for some help

 

[jellyfish420 10+ year member]

33hz = 11.75in

 

[Thuracine187 10+ year member]

could you tell me how you got that so next time i dont have to ask for help please

 

[jellyfish420 10+ year member]

Av*(1.84*10^8)

______________ -(.823*sqrtAv)=port length

Bv*((Fs/.159)^2)

Av= port area(in^2) Bv=box volume( in^3) Fs=tuning frequency Sqrt=square root.

 

[LBX2G 10+ year member]

yo jelly i am guessing this is for tube ports.

 

[Thuracine187 10+ year member]

thanks again

for slot port right?

 

[jellyfish420 10+ year member]

im gonna be making a box for my 2 12w0 in the near future. Its gonna be all 1 box with a divider so each sub will have about 2.3 cubic feet and its own port. the port legth is where i get the problem.
my max width for the whole box is 40in and gonna be using 3/4 mdf with a divider so thats 37.75 internal width

40 - 1.5 - .75(for divider)

each sub

width = 18.5

height = 16.5

port diameter = 5

when i plug all the numbers into the pL formula i get like 81.3in. that seems a little big to me. so if some could tell me if that is correct and if not point me into the right direction i would really appreciate thanx.

5" port diameter...and diameter isn't used for slots. so i just assumed he was using pvc or something...

 

[Thuracine187 10+ year member]

need lenght for slot port sorry that i wasnt clear about that

 

[Nikuk 5,000+ posts]

tube, slot, triangle, whatever... shouldnt matter in the math. You just need port area and total port displacement.

 

[jellyfish420 10+ year member]

thanks again
for slot port right?

you didn't say slot. but a 16.5x2" slot would be 29" long still tuned @33Hz, but now with alittle over double the port area.

 

[LBX2G 10+ year member]

**** jelly what program are u using or are u doing this all in ur head.

 

[Thuracine187 10+ year member]

im lost now