shared airspace or not?

is it better to have 3 seperate sealed chambers or one big sealed chamber? ive "heard" if all subs share the same airspace you can gain 3 db's. i have 3 audobahn alum12q's im going to build a box for and i cant decide which way to go. ive never noticed much of a difference but maybe cleaner when all shared. maybe because they are all getting the EXACT same amount of airspace per sub? any opinions would be very appreciated. 

I've done it both ways and prefer to use separate chambers. I'm not saying using one chamber won't work well, but building the enclosure with separate chambers increases the rigidity of the enclosure and is easier than calculating the volume and number of additional braces needed for the larger chamber. If you're just looking for that additional sound pressure output and aren't as concerned about any potential loss in sound quality, go for it. It's quite possible you won't even notice a difference between the two, but if any one of the subs goes out, you'll have to shut 'em all down until you replace it.~wirewise~ Verify all wiring with your meter before making any connections!

All individually sealed is usually the better way. A more rigid box and all of the benefits above. If one airspce is used, unless some serious wave engineering is done and there are internal baffles, some cancellation will occur, which could make the bass muddier and/or quieter. The general choice is to go seperatle chambers. I've never heard of a 3db increase from one chamber, and don't see how it would be possible. Point source 3db and other stuff, but never shared airspace - that generally leads to lower numbers./NyxBass