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BOOKER
05-31-2005, 10:20 PM
I posted a few days ago some comments on my W3's ported enclosure.
I'm kinda confused on this issue on port area, port length between slot ports and round ports. :uhoh:
I see the use of slot ports kinda new, I remember back in the day when all you see on speaker enclosures where round ports, and sounded great, and you can still find them on home stereo speakers.
So now what's the deal on switching to slot ports, I remember the manual of my W3's v1 they recommended ported enclosure used a big *** 4" diameter hell long port, now on my W3's v2 they recommended using a slot. :(
What's the issue with port noise, I don't see how now round ports make noise and slots just don't. :rolleyes:
Can someone explain this to me please, I know there are a few around that don't get it either.

:wallbash:

bcarpenterfhl
06-01-2005, 07:06 AM
its not that round ports make more port noise, infact it is often the opposite. its that with pvc sizes, you are often limited to 2, 3, and 4 inch diameter pipes (any larger, then you will likely have a long port that may need a bend. and for some reason, people dont bend pvc ports), which limits the amount of port area you have. with a slot port, you can alter the port area to your needs, and easily create a bend in the port. thats all.

DFW40
06-01-2005, 08:34 AM
its not that round ports make more port noise, infact it is often the opposite. its that with pvc sizes, you are often limited to 2, 3, and 4 inch diameter pipes (any larger, then you will likely have a long port that may need a bend. and for some reason, people dont bend pvc ports), which limits the amount of port area you have. with a slot port, you can alter the port area to your needs, and easily create a bend in the port. thats all.

Like bcarpenter said it can be a real problem to work those round ports when you get around 30 and 40 inches. But do not be afraid to use a 90 degree elbow from Home Depot or Lowes. I use them all the time to make bends and they work fine.

http://media.doitbest.com/products/435775.gif

tRiGgEr
06-01-2005, 10:26 AM
I find a slot port to be easier to design. And it looks better:)

And where Am I going to find a 7" pvc pipe??? I don't like using two of em.

DFW40
06-01-2005, 10:53 AM
I find a slot port to be easier to design. And it looks better:)

And where Am I going to find a 7" pvc pipe??? I don't like using two of em.

I go one in my pants....but seriously

It really depends on the sub, if we are talking about a W3 or a Type R that is either a 10 inch or 12 inch you can easily get away with a single 4 inch pvc with zero port noise. It is when you have a 15 inch XXX or Brahma or W7 that have to have massive amounts of port area because of the air that they move and that is when the slot port is a must.

BOOKER
06-01-2005, 02:37 PM
Thanks everybody for your comments.

I think what I really want to know is how to calculate the port area, I mean what is the formula, how do you know the necessary amount of port area needed for each sub?

Somebody said you can get along a 4" pipe and go with zero port noise, I think that's because it has the necessary area for making no noise.... from where did that size area came out, how do you know how much port area makes no noise.

I hope I had explained myself. :(

Thanks again for your support and excuse me if I'm too dumb :wallbash:

:thumbupw:

DFW40
06-01-2005, 02:57 PM
The bigger the sub and the more xmax or excursion the larger the port needs to be to allow the extra air to flow through without noise, there are other factors that play into port noise like box size and tuning. I have learned through experience but there are webpages that have formulas for this type of thing. It is easier to get port area from slot ports since you can make it as large as you want. A slot that is 12 by 3 would have 3 x's 12= 36 inches of port area.
Round port area is figured by pie x's (R squared) or 3.14 x's the radius squared so a 4 inch pvc would be pie(3.14)x's radius (2) squared so. 2 squared is 4 and 4 times 3.14 =12.56 inches of port area. So you would need (3) 4 inch pvc ports to equal one 3by12 inch slot.

tRiGgEr
06-01-2005, 03:08 PM
http://www.carstereo.com/help2/Articles.cfm?id=31

Here you go.

DFW40
06-01-2005, 03:14 PM
I just find it hard to believe that a 12 inch Brahma in a box tuned to 32 hz needs a minimum area of 50 inches.

tRiGgEr
06-01-2005, 03:23 PM
I just find it hard to believe that a 12 inch Brahma in a box tuned to 32 hz needs a minimum area of 50 inches.

Don't take that site as the holy end all of port design lol. Just use it as a guide.

I find the XXX 12" to need a minimum of 36 square inches of port area at full excursion. But the site recommends 50??? So It's not 100% the way to go.

DFW40
06-01-2005, 03:25 PM
Don't take that site as the holy end all of port design lol. Just use it as a guide.

I find the XXX 12" to need a minimum of 36 square inches of port area at full excursion. But the site recommends 50??? So It's not 100% the way to go.

tru dat