Port Size

 I have a 6"x14.9" port installed in a box

The speaker calls for a 5" x 14.9"

anyone know what I Should cut the port down to?

6" X ???

El Sandman

Hey Mr Sandman,

It's hard to guess acurately without ALL parameters but when you enlarge port diameter the length increases,  so you'd end up with something like a 21 inch port...if you have the room...

I DON'T HAVE ANY MORE ROOM FOR THIS PORT IT'S ALREADY AT THE OTHER END OF THE BOX ! ! !

I CAN PULL IT OUT ABOUT "1 OR 2".

ANYWAY THE BOX IS 30" HIGH 50" WIDE 11" WIDE AT BOTTOM AND 7" AT TOP ABOUT 3.3 Ft OF AIR. ITS RUNNING TWO 15W3 THAT ARE WALLED OFF FROM EACHOTHER

CAN I ADD A SECOND PORT?

EL SANDMAN

Hey, I popped your box into winISD, and and came up with some numbers. (I used the D-4 DVC subs, cause I had those already in winISD) Basically, you're right in the right ballpark. I don't get an air velocity, but if you're not getting whistling, you're looking good how you are now. It looks like you're tuned at somewhere in the 32-38 Hz region. I'm not certain, but I think re-tuning isn't going to change much at all right now, without major box changes. The best thing you can do is get that port to about 2"-3" away from the back wall and you should be fine. If you do just feel that "need" to get in and change anything, you should work towards parhaps turning the port towards the middle to add a slight bit more port length. That might lower the tuning like 3-6 Hz, which truthfully isn't that much. I think you're looking about right for now.

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I just re-read your post and realised that you're working with "TWO 15W3 THAT ARE WALLED OFF FROM EACHOTHER" in 3.3 cubes. How is that? Where is the port? just on one side? I'm not sure how you're doing this. I also realised that you're running way low volume for these subs. JL recommends somewhere around 3.25 cubes for a ported box for EACH woofer. Now, it's entirely possible that you means 3.3 cubes per woofer, and a port 6"x14.9" for each woofer. In which case, the above summary holds. If you're running both in just 3.3, I'm curious about box design with (1) port and how they sound in so small of a space. If that's the case, You may do better calling JL and seeing what they have to say.

Okay, I ran the numbers on your box, and if those are outside mesurements and you are using 3/4 mdf, I get 6 cubes. So I'm assuming that my first write up was right. Good luck.

3.3 to 3.5 Ft per 15W3 and 6" X 14" port per side.

When the lows hit, I can feel some bass but not as much as I should.

the folks down at the local shop used Heavy Duty Liquid Nail for the ports
and the ports will not budge.
I could always cut 'em out and start over!
so what size ports should I use?

Remember that the goal here is LOOOOWWW BASSSSSSS

El Sandman