View Full Version : Box design help with ports

06-05-2009, 02:58 PM

I am working on the design for my new box for my truck. Putting in two 10" type-rs. I am planning on using single chamber with two ports (one at each endof the speaker face) because my console won't allow a center port. Is this a good idea or is one on the side enough?

When tuning this box, should I calculate it as half the box for each sub using L shape ports? One more question, is Vb the inside volume with the port or without when calculating port length?


06-05-2009, 04:29 PM
That's one way you could do it, design an L-port box for each of the subs and then combine them when you build it. Just be sure to account for the 3/4" mdf wall that you won't be including on each of the "boxes". The best way would be to calculate it as one box though. For example, one port that is 4 inches wide and 8 inches tall @ x length wont necessarily have the same tuning as two ports that are 2 inches wide and 8 inches tall @ x length. Even though they have the same port area, the two port setup has a larger surface area lining the inside of the port and that adds air resistance. It's the same reason you don't want a port that is 1 inch tall yet 35 inches wide. I'm not saying 2 ports would be bad, it'd just be better to calculate it all as one box if at all possible. Win ISD is a great program. You can type in the volume, the exact specs of the sub, the size and number of ports and desired tuning frequency, and it'll give you port lengths needed and show you the band of frequencies that your sub + box combo will perform well in.

Sorry if this is too much information, looks as though this is your first post here on ca.com. I hope I didn't overload you with too many tech-tips :crap:

06-05-2009, 05:53 PM
Thank you for the info!

The only reason I wanted to do 2 ports is because I have a very wide but not too deep box an didn't know if one port on the side would sound right. Would it be ok? Is a 4wide x 18tall port big enough for a 5.25 cu ( without port disp taken out) big enough or should it be wider? And is it a problem to use the wall as one of the sides of the port? Thanks

06-05-2009, 07:31 PM
One more question: When calculating vent length, in the formula do for Vb do you use the inside volume without subs and port displacement? Otherwise, I do not see how to get the port displacement before you calculate vent length. Thanks