I have 4 FI BL 12's and was wondering how many cubes net should I build an enclosure for them? Also how low should I tune to do hair tricks? They will be seeing a little over 6,000 watts of power.

I'd do 2.5 cubes per 12 tuned to like 28 hz if you want hair tricks!

Id say do more around 2 cubes per sub, with ~ 40 sq inches of port area per sub also. So ~8 cubes net with ~160 square inches of port. Tune it between 30-35 hz and you'll be moving massive amounts of air.
I gained output and bandwith when i went from 2.5 cubes to 2 cubes. 

Ok so I should do two separate ports in a common chamber right?

No 1 port for the whole chamber.The port for each sub x2 for your common port.

Edited April 18, 201312 yr by pmureika

I have the single port down the middle now and it seems like the 2 subs close to the port opening are just moving and not really producing sound.

The subs should be as far away from the port as possible.

Can you put it to the side then? You should have at least 190 in2 port area. That's for 30hz.

Yes I can put the subs closer to the middle and then have the ports on the edges?? The way it is now 2 of the subs sit right at the port opening.

I just put a picture up on my profile of the current enclosure

I would put all 4 subs on one side and have the port on the other.

Ok I am going to try that and see how it works. With the power I have and 4 of those subs if I tune down to 30hz and have the correct airspace it should make me dizzy

The guy that's helping me with the enclosure is loading all 4 subs close to the center and putting dual ports on the edges. 2 cubes net per sub tuned at 30hz!!

You would get more room if you put port just on one side and subs on the other.

Yeah I kind of figured that....

The final results in for the enclosure....8.15 cubes net tuned to 31hz with 118 inches of port. Will this work?

I am building a new enclosure. This one will be around 10 cubes tuned to 31hz with 150 square inches of port.