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There's part of the problem. The Kicker is one of those medium 'Q' drivers that is less than ideal for free-air. Lots of moving mass and lots of travel but not much in the way of self sufficient shock absorbers. So that's loose, undamped and that transmits vibration. I've even seen mis-applied woofers create enough vibration to cause the throttle to shift position. So that is not the result of a true IB woofer. Also, any good air suspension or bass-reflex woofer deserves a rigid .75" baffle with zero flex. Any IB woofer requires the same consideration. If it is just mounted to .3125" thick fiberglass you are going to have lots of boat resonance. Adding more woofers to the same plane taxes the structural rigidity even more. Plus, tuning, crossover selection, bass boost, can all undermine any woofer in an open field environment, particularly an IB.
There's no doubt that bass-reflex or a bandpass will pick-up extra output over IB or sealed. But excessive boat vibration is not a byproduct of IB. It's a product of selection and execution.
I beefed up the Fiberglas with 3/4 inch birch plywood on the speaker plane. The problem is all those compartments are connected behind the scenes and due to the air movement, and lack of structural strength in the other parts of the boat everything would resonate. Now that I don't have a back wave (IB) going inside the boat, everything sounds so much better.
I beefed up the Fiberglas with 3/4 inch birch plywood on the speaker plane. The problem is all those compartments are connected behind the scenes and due to the air movement, and lack of structural strength in the other parts of the boat everything would resonate. Now that I don't have a back wave (IB) going inside the boat, everything sounds so much better.
Yes, but now you have a front wave inside the same boat structure. A 180 degree shift in polarity makes no difference. The real issue was using a non-IB woofer in an IB application. It's like a hammer without a spring and that is precisely where the excessive resonance is generated and begins. I've done countless doubled-up IB woofers (using a true high 'Q' IB woofer) with no such issue. Yet every Nautique with an OEM low 'Q' Polk MM woofer used in an IB application has this same problem. Switch out the woofer and the problem disappears.
