Ports for 3 JL 12w3d6

Hi,

Im trying to figure out my port sizes I need.  My box is 5.22cf 1chamber.  JL was recommending (4) 4in ports 18inches long.  From the design of my box I cannot fit that into it.  I checked the port configuration on this site and if I use 4 3in ports @ 12inches long I'd be tunned for around the same frequency.  Whats the diss-advantage of using 3 vs 4in ports?  I did a search here and port noise came up.  But they also said if the port is big enough it shouldn't be a problem.   So is 3in ports Okay?   Either way also, im going to have to put then on the side and not on the same side as the subs.  All 4 ports will be on the same surface though.  I was going to in at the upper end of the box and elbow down.  I MAY be able to crunch 4" ports in there but 3" would be MUCH easier & I know they'd fit  I have already finished the cosmetics of the box so a slot port is out of the question.    Any sugestions?

Thanks in advance!

Whats the diss-advantage of using 3 vs 4in ports?

Not enough port opening area, which causes port noise at high volumes.

Too bad a slot port is out of the question...because it is your answer.  But the big question is:  how in the world did you finalize the box design without incorporating the ports into it?

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Well,

I sort of got too invovled with makeing sure it was going to fit with angles and amp space that I didn't incorparate for the slot.  I thought I wasn't going to have enough cubit ft. to port it and originally going to seal it.  I could (but it would destroy the finish of the box) put a slot at the bottom but I still dont think that would work.  Im thinking if its going to be a slot it has to be on the same side as the subs.  Am I wrong?  I could cut a slot out of the bottom of the box and fix a peice inside.  But you'd recommend 4" over 3" then correct?  I could try to squeeze them in, its just going to be tight..

I have one more issue that you may be able to answer also.  I wired it to 1 ohm at first and the subs would pop even at low volumes.  4ohms it runs fine but I feel I need to push more power to them.  Im running them with a Rockford T20001.  But after I port them anyway I may be pushing them to there limits.  I was experimenting with sine waves to try to see if it was a power issue, but nothing was showing on the scope.  But maybe my scope settings were not fast enough to triger or capture the pop.  I didn't have much time whe nI was trying it.

If you can put round ports on the side or top then you can put a slot port in one of those places also.  The function is the same.  Of course, the face is preferred.

The popping was the amp telling you that you were trying to kill it.  If it works fine at 4 ohms, that is where you should leave it.  You'll get more output with less power using a vented box over a sealed one.  If that still isn't loud enough, you can switch out the subs to be able to get to 2 ohms.  Or buy a more powerful amp.

But I'm getting lost here...do we know what and how many subs you are using?  OOPS, oh sorry, I see it in the title.

Oh gee, you should forget the ports altogether with those.  You'll get a really nice response leaving that box sealed.

Ohh,

also the reason why I was going to use round ports is because they would fit inbetween the subs when I go in on the side and elbow down.  That was my other advantage.  I was also thinking of porting them on the bottom of the box and then have the ports come straight up and put a 90 in and come back down be around 3 - 4" from the bottom of the box.  Would it work?

Thanks for the advise.  I will keep the box sealed.  I am going to try to fill the chamber about 1.4-5 cu.ft. so I can get with in the specs they recommend.  I was on the very edge of being able to port them though. 

Thanks again!