i'm missing something about ports

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10-01-2005, 09:10 AM

zzzzzzz

4000 Watt CAFz'r

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why would you have more than one port ?

if you have two ports, how do you find out how long they are ?

why does your port get longer when you go from a 3" to 4"?

10-01-2005, 09:42 AM

WD21

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Join Date: Feb 2005

Posts: 603

have you done a search? if not, DO ONE. you will learn alot.

you dont NEED more than 1 port, some people use more than one to reduce port noise. to find out the lenght there are many calculations you have to do. or you can go to: http://www.carstereo.com/help/Articles.cfm?id=31
that will give you a pretty good idea of what you got to do. the length gets larger going from 3-4 because you gain surface area going to the 4".

10-01-2005, 10:48 AM

GrizZz

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Join Date: Apr 2004

Posts: 756

Mine has dual ports so that I can plug one when required...

Both open, ~50hz for competition.

One plugged, ~33hz for daily driving.

10-01-2005, 11:33 AM

Starterwiz

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Posts: 870

What's the finish on that box Grizz?

10-01-2005, 12:13 PM

WD21

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^^^ bedliner

10-01-2005, 01:37 PM

The A Team

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Quote:

Originally posted by Starterwiz:
What's the finish on that box Grizz?

That would be Linexx.

10-01-2005, 07:22 PM

Team Stupid SPL-Chris

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Any tests if you gain with linexx over straight resining??

10-01-2005, 08:07 PM

GrizZz

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Join Date: Apr 2004

Posts: 756

No, no tests...

My buddy owns LineX Calgary South. He was at my shop one day and noticed my box in the back of my van, which was just plain MDF, no resin at all... "Wow... that's impressive. You should let me spray that."

"Sure..... do it for a case o' beer?"

"Yep, sure!"

It improved SQ and SPL out of the box a lot... How much, I dunno. But it was very noticeable.

10-03-2005, 12:49 PM

Paul Niwranski

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Quote:

Originally posted by dumbest:
why would you have more than one port ?

if you have two ports, how do you find out how long they are ?

why does your port get longer when you go from a 3" to 4"?

1) Often a single round port is not enough port area for the woofer(s). Or if your design calls for a single 6" for example, this may be undesirable according to your layout so you have to move to multiple smaller vents.

2) For multiple vents you either have to add their areas together and work it that way or hope your vent tuning program has a feature for multiple vents. The posted link above both calculates your minimum required area and can accomodate multiple ports.

3) To tune a section of pipe to a certain frequency, as the diameter increases, so does the length.