help with tube ports

[BLD 25 10+ year member]

Hey, i have decided i am going to use pvc ports because the slot port box would be huge.

I am building for two 10" infinity perfects. They recommend 1cube per sub, ported at 35hz with a 3" X 10.35" port.

Questions:

how much space has to be at the bottom of the port between it and the box?

Would a 4" port be longer or shorter? How do i convert?

If it is too long, how do i convert this to two ports?

any help or redirection to a program would be great,

thanks!

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[tRiGgEr 5,000+ posts]

how much space has to be at the bottom of the port between it and the box? At least 1 and 1/2 of the ports diameter minimum.

Would a 4" port be longer or shorter? How do i convert? Longer http://www.carstereo.com/help2/Articles.cfm?id=31

If it is too long, how do i convert this to two ports? Use the link supplied.

any help or redirection to a program would be great, look above link.

thanks!

That port will tune the box to 39hz.

Remember - Radius^2(3.14)= circle(port) surface area.

 

[BLD 25 10+ year member]

?? i am still a beginner, back up a little. here is the link to the info.

http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/PERFECT10.pdf

 

[concept11253 10+ year member]

You should try to go with slotted. The recommended port area of the box with a slot port is around 31sq inches. You are going to need a minimum of 2x 4" wide ports. Or else you are going to have some serious port noise.

EDIT:

Your going to want 2x 4" wide ports for EACH sub at the minimum.

 

[BLD 25 10+ year member]

You should try to go with slotted. The recommended port area of the box with a slot port is around 31sq inches. You are going to need a minimum of 2x 4" wide ports. Or else you are going to have some serious port noise.
EDIT:

Your going to want 2x 4" wide ports for EACH sub at the minimum.

What is your evidence or support for this? I have read TONS of threads that say that there is very little port noise if any(or any sonic difference for that matter) with tube ports and that they are more than sufficient. The slot port plans have a huge amount of slot area which contributes to a much larger box than i was wanting. Thanks for the help though.

 

[tRiGgEr 5,000+ posts]

He is right. 12.56 square inches of port surface area will not be enough. It is true PVC/Aero ports have less port noise when compared to a comparable slot port. But one 4" port will not be enough. With a tunning on the box of 39hz it will require 25-31.33 square inches of port surface area to avoid port noise.

At least 2 4" ports are required.

 

[BLD 25 10+ year member]

Ok, so how do i figure out how long and wide of a port i need to do? I was wanting 32-35 hz? Thanks!

 

[DBfan187 5,000+ posts]

http://www.psp-inc.com/

 

[tRiGgEr 5,000+ posts]

Using the link I supplied. Enter your boxes parameters. Scroll to the bottom part of the link. Enter type of port, quantity of ports, everything required. And it will calculate it for you.

Example - 2ft^3 with two 4" PVC ports. For a tunning of 35hz they would each need to be 24.75" long.

If you were to build a slot port of 10x2.5 it would need to be 22" long.

Remember the PVC ports create displacment, so calculate the volume of air they take up and deduct it from your box's internal volume.

 

[BLD 25 10+ year member]

Using the link I supplied. Enter your boxes parameters. Scroll to the bottom part of the link. Enter type of port, quantity of ports, everything required. And it will calculate it for you.
Example - 2ft^3 with two 4" PVC ports. For a tunning of 35hz they would each need to be 24.75" long.

If you were to build a slot port of 10x2.5 it would need to be 22" long.

Remember the PVC ports create displacment, so calculate the volume of air they take up and deduct it from your box's internal volume.

Sorry, i didn't see tha you supplied a link, you hid it in my quote. I don't read my quote. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif thanks, i'll look at that.

 

[BLD 25 10+ year member]

http://www.psp-inc.com/

thanks butt man, i'll check it out.

 

[DBfan187 5,000+ posts]

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=268-352

 

[BLD 25 10+ year member]

wow, so what do i do with the figure that infinity gave me that said 3" by 10.35" for one sub?

Also, i used the program and it recommended a 5" by 39" port which is rediculous. With 2" ports it was a managable lenght, but are they too narrow?

 

[concept11253 10+ year member]

Yes wayyy to narrow. You need 3" minimum but your going to need atleast 4 for your 2 subs. I would actually recommend like 8 of them.

Imagine the pressure built up in the box being cramed through a small opening when the sub its. Its gonna make alot of port noise. Its like letting the air out of a ballon. All that air in the box coming through a small 2" opening is not going to cut it.

 

[concept11253 10+ year member]

What is your evidence or support for this? I have read TONS of threads that say that there is very little port noise if any(or any sonic difference for that matter) with tube ports and that they are more than sufficient. The slot port plans have a huge amount of slot area which contributes to a much larger box than i was wanting. Thanks for the help though.

Your definitely right, but it assumes you have the proper amount of port area. I have tube ports on my box and I have no port noise. When the tube ported boxes are built right, there is no difference between slotted and ported, just the style of port.