i asked a friend of mine who is very knowledgable with enclosures and f-bodies (but puts a lot of stock in modeling programs, which i dont) to help me with the port designs on my box. i was shooting for a 4 ft^3 @30 hz box, when i asked him about it, this is the reply i got. he recommends 33hz, but i was shooting for 30 because i want this to hit LOW.
To be honest with you, I think 4 cubes for those 2 subs is too big. The Qts on these subs is so low, that they really want a smaller box. I found that 1.5 cubes (each) tuned to 33hz gives a nice flat response. With the 1.5 cubes per sub (3 cubes total), you'd need 2 4" ports at 17.4" long each, or 3 3" ports at 15" long each.
If you jump up to 2 cubes per sub (4 total) tuned to 30hz, the response thins out between 40 and 70hz, which I feel will hurt your overall bass response. But... at that size, your ports would be 15.5" long for the pair of 4" ports, and 13.37" long for the 3 3" ports.
i was thinking 2 ft^3 was perfect for a ported rl-p 12. should i go ahead and do the 4 ft box or take his advice and do only 3? for the ports im using 2 4 inch aeroports. are the lengths he gave me about right? anyone else have any thoughts on this? if i have to, i can build it another inch and gain about another cubic foot, so i can go up to 5 if i have to.
its goin in a firebird trans am, so the design is quite unorthodox. here are some pictures of my current sealed box. im basically going to build the same thing, just with a rectangular section extending about 1 and a half feet up to the backs of the back seats, box will be completely level at the top, and the added section will be 4-5 inches tall. im going to start on the box on my next day off, just going to build it, then get the exact size to cut the ports but i think i'm going to do it right at 4 ft. ill get plenty of pics
someone told me i might be better off with 2 4.5 inch ports a bit shorter than 4 inch ports and longer, but i couldnt find them anywhere. links to good prefab ports?