Round vs. Slot port

[bikinpunk 10+ year member]

I was going to go with a 4" round port giving a port area of about 12.5^2".

I e-mailed JL to ask what they suggested in my certain case (I gave tem alot of details). For my requirements the person replying said to use a slot port because I need 25^2" of port area.

My question is, how does this really effect things? Is it really necessary that I go with slot? A slot port will be much heavier, and harder to tune later if I change my mind on tuning frequency.

I plan on building tomorrow.

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[Immacomputer 10+ year member]

If you want to change the tuning later, use two 4" diameter ports. This will give you 25in^2 of port.

 

[phantom240 5,000+ posts]

OR... you can build it right the first time.

If you really wanna do something neat, make it a slot port and make 2 ports. Make one port so that you can seal up that one or leave it open, changing between 2 frequencies (DD and comp?). I think that would be pimp

 

[bikinpunk 10+ year member]

I don't have enough room to do that.

The box is going to be:

Length 27.00

Depth 13.00

Height 13.00

I won't have enough length to run 24" ports, I don't think. I maybe could extend the lenght another inch or two, though.

Can you explain why I would want to have more area? From everything I've played around with graph-wise, there's no audible difference, excursion difference, or SPL difference.

 

[bikinpunk 10+ year member]

OR... you can build it right the first time.
If you really wanna do something neat, make it a slot port and make 2 ports. Make one port so that you can seal up that one or leave it open, changing between 2 frequencies (DD and comp?). I think that would be pimp

That's a TON of work to go through when I could use aero ports and pull it out, and cut as needed. I've also built a snake-ported enclosure once and it was a pain...not to mention heavy as crap.

Cabin gain is a huge factor here. I've calculated everything as much as I can, but things on paper don't equal real-world experience. I may or may not want to change the tuning a tad, and to have to completely remove tear apart a box to do that is out of the question.

 

[Immacomputer 10+ year member]

With too little port area, there is a chance you will get port noise. If you're going to be running a w7, you will be moving a ton of air and with only 12.5in^2 of port area, you will probably get some port noise at and around tuning. This noise will limit output where it occurs as well.

 

[phantom240 5,000+ posts]

That's a TON of work to go through when I could use aero ports and pull it out, and cut as needed. I've also built a snake-ported enclosure once and it was a pain...not to mention heavy as crap.
Cabin gain is a huge factor here. I've calculated everything as much as I can, but things on paper don't equal real-world experience. I may or may not want to change the tuning a tad, and to have to completely remove tear apart a box to do that is out of the question.

I hear ya there. I built a ported box recently that was 36x24x12 with a big slot port that was like 60^2 inches of port area and it weighed a shit ton as it was. Sounded beautiful though.

 

[mazdakid 5,000+ posts]

i get port noise with 2 4" round ports with a type r 12, so you might need a little more

 

[bikinpunk 10+ year member]

Thing is, that I don't have hardly any noise at all with my current setup, and I'm only using one 4" tube.