tuning a box?

[pitbull12888]

wuts the equation for figuring out how to tune your box? im thinkin about startin to make them to sell.. made some pretty 1s but never 1 that was tuned in

thx for the help ahead

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[pitbull12888]

1 person took a look? come on yall lol

 

[Tiger Bass 5,000+ posts]

I personally dont know to be honest, but check the stickies. They give you lots of good stuff. Its where I got my plans for my first ported.

 

[pitbull12888]

thx will do

 

[Big Dee 10+ year member]

You can use WinISD to calculate port tuning.

 

[itzme218 10+ year member]

check my thread it might help ya...i'm also learning, MTX support site and JL support site are good.

 

[pitbull12888]

Quote:

Originally Posted by itzme218

can someone tell me what i'm doing wrong here

where : Av = 3x16.25

Lv = 14.75

Vb = 4.5

ok checkd it.. now if someone can just tell me wut av, vb, and lv stands for im good to go.

 

[pitbull12888]

ok so i found out vb = volume what about the other 2

 

[Immacomputer 10+ year member]

I wouldn't recommend crunching numbers by hand as it is not always very accurate.

Download win isd from this site:

http://www.linearteam.dk/default.aspx?pageid=forums

From there, you can calculate your port length based on tuning frequency and box volume.

There are three main variables when discussing the tuning frequency of an enclosure:

1) Port Area (Av)- This is the opening or cross sectional area of the port. This area needs to be maintained through the length of the port.

2) Port Length (Lv)- This is how far into the enclosure that the port extends. This is found by measuring down the center of the port.

3) Box Net Volume (Vb)- This is the volume of the enclosure minus all bracing, sub displacement, and port volume (port volume is equal to Av*Lv).

Here is the basic relationship between the three variables and do note that their relationships are not linear.

1) Increasing Port area and keeping Vb and Lv constant increases the tuning frequeny (Fb). Decreasing port area and keeping the others constant will decrease Fb.

2) Increasing Port Length and keeping Vb and Av constant will decrease Fb. Decreasing Port length will increase Fb.

3) Increasing Box Volume while keeping Av and Lv constant will decrease Fb. Decreasing box volume will increase Fb.

The problem with calculating this using a basic formula is that with different cross sectional area, you will have different surface area on the port walls even though the cross sectional area is equal. For instance, a really tall and skinny rectangular port, that shares the same cross sectional area as a round port, will have more area inside of the port than the round port will have. The rectangular port will also have corners that can restrict air flow in the port. These two factors will change your actual tuning frequency but when calculating them, they will have the same port area and thus the same lengths given a constant enclosure volume.

Winisd takes this into account and will adjust your port length accordingly thus making things much more accurate and closer to what you really want.

 

[colgatekillaa 10+ year member]

im goin with port tubes, seems to be a lot easier.

but does this come at a price? will it not sound as good?

 

[Big Dee 10+ year member]

im goin with port tubes, seems to be a lot easier.but does this come at a price? will it not sound as good?

I think slots are easier, but either way the sound won't be any different.

 

[pitbull12888]

ok thanks for the link and the info

 

[pitbull12888]

so im gonna be makin a box to custom fit the trunk and its a big box so im cutting off sides for each sub. its gonna have a 12w3v3 in each box with each box tuned to 43.7 = recommended hz for the sub... sound about right?

 

[Tiger Bass 5,000+ posts]

From what Ive read on other posts, thats pretty high man. I would drop it down to 40 hz at least. 35hz seems to be about average though.

 

[pitbull12888]

ok then thanks... any1 else agree?