Sub Box Porting

[peetie87]

Hi. I recently purchased a dual sub box (http://i12.ebayimg.com/05/i/06/5e/c9/44_1_b.JPG) for my GNX-104 subs and i want to make the box ported. Where should i put my ports on the box? I am going to have the box positioned so the angeled side is facing up (subs pointing up). Does is matter where the ports go? Polk reccomends a 3"wide x 8"long port for a 1.25 cuft box and the box i purchased is two 1.25 cuft chambers. I was planning on purchasing 2 of these port tubes and cutting then 8"long (http://cgi.ebay.com/3-Wide-Nickel-Port-Tube-12-Long-Cut-to-Size_W0QQitemZ5859074686QQcategoryZ14932QQssPageNa meZWDVWQQrdZ1QQcmdZViewItem). Are these ports a good choice? Does it matter what material the ports are made of (ie plastic vs. metal)? Please let me know -Alex

[neomagus00]

there is a small problem here - when you actually put the ports in, then put the subs in, the actual volume is rather less than 1.25 ft^3, which will affect the tuning... what i'd do is put the ports in at full length as a trial, then trim them back bit by bit till you like the sound (where a 'bit' is 1/2 inch at most)... this is annoying, but if you cut them too short, you're screwed until you get new ports...

and no, the material doesn't matter

[peetie87]

ok thanks. What about location on the box? Does this matter?

[AustinKP]

ok thanks. What about location on the box? Does this matter?
yes.

(I'm channeling Cody here with my one-word answer :) )

[neomagus00]

ok thanks. What about location on the box? Does this matter?
it can, yep... this will add a whole new order of magnitude to how annoying the initial set-up will be... because every time you take some of the vent off, you'll need to try the box (with its new and hopefully improved tuning) in each position in the trunk that you'd consider... so if you have three positions in the trunk (say, left, rear, and right), every time you trim the port, you need to listen to the box in each of those three positions...

this is the most thorough way to do it, but also the most time consuming...