sound waves comeing from subs arent just those 2D pictures you are used to seeing, they are 3D and go throughout the entire car everytime the wave bounces of any surface in your car that is the effect of another sound wave to cause cancellation... i mean seriously, do you know what cancellation is? the difference in cancellation in same sub and different sub setups isn't really all that much to worry about sound waves are huge!!! it's not too easy for them to cancell significantly in any senario... after the waves have bounced a few 100 times yeah cancellation probably have a big effect, but at that point, so what?
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