questions dealing with square ports

[DarkFox 10+ year member]

Hello, I am going to be building a box for a friend soon and had some questions. He is getting 2 15" kicker L7s and I am going to build him a box to the "Street Bass" specs as listed in there manual:

4.5ft cubed + Port displacement, 3" X 16.25" X 14.75" long port (displacement and port per sub.)

I have always used round prots in the past and was looking for info about squares. Specificaly, with round ports I always kept a 3 inch bouble clear around the end of the port inside the box. With a setup like the one i am building though, is it ok to use the top and bottom of the box as sides to the ports? also, how much room should I leave behind the port.

I also wanted to use only one port right in the middle, Is it acceptable to just add the mesurements together and make one port, 6" X 16.25" X 14.25"

All right. thank you very much for any help.

Click to read more...

 

[Volenti 10+ year member]

It is ok to use the sides of the box as a part of the port.

Same clearance rule applies to slot ports, except you use the narrow dimention, however, try to not exceed a 10:1 ratio in the opening of the slot, it can effect tuning.

You can't just add the port diameters like that, you need to add the port area, online calculators are your friend.

 

[DarkFox 10+ year member]

Correct me if I am wrong.. if you are talking area. then this should be the math:

3 X 16.25 = 48.75" squared

2 ports would then = 2 X 48.75" = 97.5" squared port area

2 ports in one, or adding the widths together from two ports (6") :

6 X 16.25 = 97.5" of port area

So why cant the ports be added to achive the same port area and volume???

 

[Volenti 10+ year member]

Ahh you confabbled me with talk of only using round ports in the past and I thought you wanted to combine round ports is this case, your math is correct.

 

[DarkFox 10+ year member]

Thanks you for the input Volenti. I was hoping that was the case.