Port Length Questions

[ascitiesburn69 10+ year member]

Ok I'm having trouble figuring out the Vent length given to me in Winisd or BBP etc.

In this Picture . Is the Vent length the length of the line that says Port length +.75 for thickness of wood. or is it port length plus 1/2 width of the port+ .75 for thickness of wood?

And in this pic: Is the port length the length of the Line that says Port length plus half of the port width plus the length of the left side Plus length of Right side? or is it just either the left or right side+ the line that says port length?

Sorry about horrible drawing //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif and if i confused anyone just LMK and i'll attempt to clarify

Click to read more...

 

[PSturmer 10+ year member]

port length is the middle of the port but it should be longer than what your calculating it to be. read about end correction here:

http://mobile.jlaudio.com/support_pages.php?page_id=165

 

[ascitiesburn69 10+ year member]

Thanks alot for that site. Very informative. Anyone else wanna chime in about ports that do not use a wall of the enclosure as a side?

 

[mattxc 10+ year member]

no, but as cities burn = amazing

 

[ascitiesburn69 10+ year member]

Lol yea they really are. I remember seeing them when they first started out. and then again with underoath at the new orleans House of Blues. **** that was a good concert.

But seriously anyone wanna help me out with this?

 

[ascitiesburn69 10+ year member]

Bump

 

[dman4486 5,000+ posts]

jeebus noobx

http://www.caraudio.com/forum/showthread.php?t=137804

look at the red lines and numbers...

 

[ascitiesburn69 10+ year member]

I looked at that but some of the pictures have the port length line extending half the port width past the port and some dont....

 

[dman4486 5,000+ posts]

I looked at that but some of the pictures have the port length line extending half the port width past the port and some dont....

it is an end correction factor, and will not make a noticeable difference

 

[ascitiesburn69 10+ year member]

If i have a 5.5" wide port then thats 2.65" extra inches which could drop my tuning 1-2hz easily.

 

[dman4486 5,000+ posts]

If i have a 5.5" wide port then thats 2.65" extra inches which could drop my tuning 1-2hz easily.

end correction is not .5 port width

 

[dman4486 5,000+ posts]

http://www.ajdesigner.com/phpsubwoofervented/port_length_equation_k.php

 

[ascitiesburn69 10+ year member]

Nice site thanks for that.

 

[ascitiesburn69 10+ year member]

when using a port length calculator do I put the internal volume before the port displacement or with the port displacement. For instance if I have a 5.8 cuft box before port displacements and the port I am going to use takes up .72 cuft, then when using a port length calculator do I use 5.8 cuft or 5.1 cuft ?

 

[dman4486 5,000+ posts]

when using a port length calculator do I put the internal volume before the port displacement or with the port displacement. For instance if I have a 5.8 cuft box before port displacements and the port I am going to use takes up .72 cuft, then when using a port length calculator do I use 5.8 cuft or 5.1 cuft ?

I use after sub and port displacement because then it will be the most accurate for the final product.