Subject:

Comments:
: Hello Tim, : Here is a some info that may be helpful. : We use about 8 cu feet per 18 in our subs. : 20 cu feet per 18 is quite large and not really practical for most portable systems. : 5.5 cu ft per 18 may be a bit small and in order to toune low your port will be smaller than is recommended Small ports sealed sealed enclosures can be quite hard on the speakers. : On the bright side: : We thrive on undersized, under ported enclosue designs. : Some speakers handle it better than others and don't have much real world experience with the JBL's you have. : You lose efficiency when you "undersize" an enclosure, you can make up for it some what by making sure you have ample power and excellent protection. : All in all you should see: : a clear increase in SPL in the 50Hz to 100Hz region if you double the speakers and the power as well. : Some level drop in the "below 40 hz" region. : If you buget restrains you from building new boxes, adding the extra speakers sounds like a nice stepping stone to get you into more 18"s, then more amps and somewhere down the road build new boxes and move the 18"s over. : I always use quite a bit of insulation in subs and though "theory" says its not necessary in well designed cabinets, I prefer the way a well damped sub sounds, especially in the highly reveberant environments we so often find ourselves doing in. : : Dave Rat : : I have four single 18" subs. The cabinets are : : 48' X 24" X 24" apx. 11 cubic ft. internal. Need more low end. I know JBL recommends 20 cubic ft per box for thier dual 18" 4719 sub. I am on a low budget and am contemplating adding an additional 18" JBL 2241H to each cabinet. I realize that I am short about 8 to 9 cubic feet on each cabinet. I thought I would add insulation to effectively increase my internal volume. : : What do you think is the downside of doing this ? Will I notice an audible increase in low end, get spl or am I just waisting my money. Thanks for your expertise

Optional Link URL:
Link Title:
Optional Image URL:

Please use the new Rat Message board located at http://ratsound.com/cgi-bin/yabb/YaBB.cgi