View Full Version : Current Box Lacking Port Area? PICS!

10-24-2006, 09:54 AM
Here is my current box and port.


Port is 6x4x16" in a 3.4cu Ft Box. I'm not sure how to do the measurement, but I think it is lacking port area. Can someone tell me?

I am thinking about doin a little smaller box. 3cu ft with more port area.


Waste of time and money, or not really?

10-24-2006, 09:58 AM
how many subs is going in the box?

10-24-2006, 09:58 AM
uhh assuming you're saying 6x4 internal dims, you have 24 sq in"

not enough for anything more than a single 12

10-24-2006, 10:02 AM
If its for a single L7 i would do ~33-35 sq. in. of port

10-24-2006, 10:03 AM
These are old pics, I've had my sub in here for like 4 months.

It's 1 12" L7

6x4 are internal

10-24-2006, 10:06 AM
You could do more, but it isnt required unless you are hearing port noise..

Are you not happy with the sound of the box?

10-24-2006, 10:09 AM
No port noise. Very happy.

Might as well just build a box for dual L7's :0

10-24-2006, 10:28 AM
Port area is the cross sectional part of the port. It has nothing to do with length but just the open area at the front of the port. It is in inches^2 so it is only two dimensional. To fond cross sectional area of a rectangle, multiple length times the width. This is, of course, not counting the wood, just the open port.

For an L7, I would do around 30-35 inches^2 of port area.

10-24-2006, 10:40 AM
actually....that would width times height. not length. but yes, you are right immacomputer. general rule of thumb is ~16 PER CUBIC FOOT AIR SPACE. that will give you (in general) optimum airflow for a daily beater.

10-24-2006, 10:42 AM
so for my 6cu ft box for my dual L7's

96 sq" of port is ample.

Port is 6" wide and 13.25" tall.

10-24-2006, 11:50 AM
so for my 6cu ft box for my dual L7's

96 sq" of port is ample.

Port is 6" wide and 13.25" tall.

even for a kicker recommended 4th order bandpass the port is 56square inches for 2 L712's
so 96 is more than enuff...the only difference...the bigger the port the longer it has to be to have the same tuning


10-24-2006, 12:03 PM
Well here is the box design (design is @ 7cubes). I am taking it down to 6 cu ft, all I have to do is (IONSQL told me to do this)...

allright man.... quite honestly, the other design will still work, with just a few modifications. First, change the 36.75" dimension to 35", and then change the 14.75" port dimension to 22.25", and you'll be at 6cf @ 33Hz. Leave everything else, double baffle, 6" wide port, etc.


So 6cuft dimensions being (can some verify this.)

Height= 14"

Width= 33"

Depth= 35"


Port Depth= 22.25"

Port Width= 6"

Port Height= 12.5"

Port Area= 75 in^2

10-24-2006, 12:24 PM
So Is this box 6cu with or without port?

I can't really understand this, I do 14x33x35 and do cubic in to cubic ft math and it comes out to like 9.3 cu before driver and port disp. What am I doing wrong.

10-24-2006, 12:58 PM
your not calculating sub and port displacement and wood end correction


10-24-2006, 04:16 PM
how do you calculate it?

What did u get for the air space of the box and port?

10-24-2006, 04:30 PM
I get 7.46cf for the box, gross. Port is 1.21cf, which leaves 6.25cf.

Factor in .12cf displacement for each woofer, which leaves6.01cf net...

10-24-2006, 07:33 PM
Hey I trust Ion, so Guess I'm all good too go.

I have to measure it out, but since you do this all the time, can this box be made with only 1 sheet of 4x8 mdf? My guess is NO.