Re: few questions for the experienced
There are a number of modeling programs that allow you to model multiple subs and boxes.
As for 4th orders, what are you trying to accomplish and with which subs? That may or may not be the best choice, depending on those and a few other factors.
No one can tell you how much space a random sized sub will need for a given enclosure. Again, it depends on the sub and what you're trying to accomplish. i.e. Do you want a burp box for competing? Do you want more mid bass for rock and metal or low bass for rap, et al? Or, do you want flat response across the entire sub bass region?
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