Port ratio help

[fecupe2001]

i dunno, i have to disagree, no offense but imo, it actually depends on the cabin itself, not the shape of the port, at least i learned that on my explorer before the wall, would love to see someone else´s tests about this rule, but it sounds to me like the infamous 12-16 sq of port per cubic feet rule

Edit nevermind, reading > me lol

haha no problem i saw the comment, i haven´t changed the shape of my wall´s port really, but when i had 4 12s and even 2 12s on the back before the wall, i got WAY louder using a port from top to bottom and 145 SQ (it was 14.5 x 10) rather than using a 12x12 port with same lenght, also tested this "rule" with 2 12s on an smaller port and still got louder the other way, my explorer also sucked ass with same port area but using a port across side to side (it was 36.5 x 4 ) when i had 4 12s, i honestly think it depends on the cabin itself

[Krakin]

i dunno, i have to disagree, no offense but imo, it actually depends on the cabin itself, not the shape of the port, at least i learned that on my explorer before the wall, would love to see someone else´s tests about this rule, but it sounds to me like the infamous 12-16 sq of port per cubic feet rule

This is actual science though lol.

In this illustration it shows how the air near the edges slows in velocity and at the extremes can even come to a stop.

If I can find the link to the article I'll post it for you, but I just have it saved to my phone.

[Triticum Agricolam]

Here is the formula Krakin was reffering to:

Equal pressure loss diameter = (1.3(X*Y)^.625)/((X+Y)^.25)

This equation give you the diameter of port that will perform the same as a port of X * Y dimensions.

Now to say that a 25" x 4" port isn't going to perform as well as a 10" x 10" port is a bit of an oversimplification. If you have plenty of port area, so port velocities are relatively low, there probably isn't going to be much, if any difference in performance. Where you will start to see a difference in when you are low on port area and port velocities start getting up there, this i where having a high aspect ratio port is going to hurt you.

[Triticum Agricolam]

If anyone whats to know how efficient their slot port would be compared to a round port you can just give me the dimensions and I'll let you know. I've got the equation put into a spreadsheet so it only take me a second to do.

[Ritch40]

what can be done if port velocities are getting up there?

i have been playing around with some ideas with both the psi platform 1 (12") and the dc audio level 3 (12") and it doesnt seem to matter what i do i either have a port that is just too long or velocities that are WAY up there. By way up there i mean 180f/sec+

I have been playing with port opening dimensions, tuning and box volumes and i just can not seem to come up with something that works right according to what little i know.

[Triticum Agricolam]

The technically correct solution to high port velocities is to increase port area. In practice this isn't always easy for reasons you already know, port gets too long, eats into box volume too much, etc.

What's the specs on your proposed system? Box size, tuning, port area, amp, vehicle, etc. Maybe we can help you come up with a solution.

[Ritch40]

ironically enough, i went from figuring a single sub to 2 subs in a common chamber and common port and things just kind of fell into place.

Thank you though....i really do appreciate it!!