port on box/tuning

[ss3079 5,000+ posts]

I'm sure I could.

- Steve

 

[OLD_SCHOOL 10+ year member]

can i msg you on yahoo i want to explain something

 

[ss3079 5,000+ posts]

Good to go.

- Steve

 

[Nikuk 5,000+ posts]

Thank you Mr. Rephrase Everything Jmac Says On Box Building.
- Steve

LMAO

that ones a classic

 

[ss3079 5,000+ posts]

LMAO
that ones a classic

Quote it, you know you want too //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

- Steve

 

[Nikuk 5,000+ posts]

Quote it, you know you want too //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif
- Steve

ooooooh okay...

out of 16k posts, you've sure found you're way into a crapton of sigs... //content.invisioncic.com/y282845/emoticons/clap.gif.178cba2c538c68e720c727fcb024b19c.gif

 

[Fitz 10+ year member]

ok, so in a 7.85 cube box (that's after subs), should i use a big long port or a short small one? also, where do i get winisd and should i guess a port volume to subtract from the 7.85 cubes every time i do the equation, or does the equation compensate for that?

oh, and not to be a prick, but steve won

 

[OLD_SCHOOL 10+ year member]

how much power and what kind of subs ? what you can do is put the box volume in winisd and the amount of power your using with the tpye of sub you are using and it can tell you how much port area you will need to keep from getting port noise which i have been told is 17.2 m/s.

like i said to before you can start with 12-14 in^2/ cube of box and see what it does. it may be way to much, it may be way to little, it might be just right. but i bet you will find that alot of the time for general car apps thats gonna be pretty close to what you can use

you need to use the net volume in the tuning before sub displacement than figure in sub displacement and port displacement (so if your subs call for 4 cubes per sub use that not 4 cubes + sub displacement if your using this equation

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

this how i understand how to do it

i am no expert and am learning this as well but i think that will work for you

also i don't know if long short wide thin makes any differance but i have heard several times that port area = port area whether its in a tube a slot or 30 ich pipe sticking out of the box

 

[Fitz 10+ year member]

so, assuming that old school is right, that means, since i have 8.15 ft^3 right now of space for box (before subs and port), i use 8.15 in the equation to figure out my tuning.. correct? then that's it?

oh, and if you're wondering about subs/power, read my signature... hopefully be switching to XXX's and brutus 2200D (2 maybe..)

 

[OLD_SCHOOL 10+ year member]

if your using this equation

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

 

[OLD_SCHOOL 10+ year member]

oh wait i am sorry that is for port lenth i am wrong

i thought you where asking how to find the length of a port at a given tuning with a box not built

i was confused but jmac got you taken care of sorry bout that

 

[Fitz 10+ year member]

thank you jmac.. so i basically have to use trial and error of different port lengths, areas, and volumes and subtracting them from the box volume, correct? also, could you answer me jmac, long and big or short and narrow.. which works better for spl?

 

[squeak9798 5,000+ posts]

For SPL you generally want more port mouth area.

BTW, has anyone else noticed that WinISD generally gives you a different port length than doing it long hand with the equation? Or am I just stupid and do something wrong. Oh, and since you asked, you can download WinISD from http://www.linearteam.org. There are many other better box programs out there, but WinISD I think is about the best free program. Not super accurate, but better than nothing I guess.

 

[ss3079 5,000+ posts]

I get different numbers when I do it by hand vs WinISD vs BBP6.

The closest seems to be BBP6 for me, though.

- Steve

 

[Fitz 10+ year member]

how much is pro? is there anything better than winisd? and do i have to keep performing trial and error with port volumes and my box with the equation then? also, jmac, is bigger port mouth better for spl?