I was thinking of getting a memphis 15-PR104 10" in a downfiring box underneath my rear drivers side seat in my 03 ext cab. The spec sheet on this thing says xmech is .352 inches (8.9mm). Xmech is maximum excursion isn't it? Am I understanding this correctly? If so that doesn't look like much movement. I was wondering how far above the floor it should be mounted.

 

Actually the term is called Xmax, and yes, it has to to with maximum excursion of your woofers. But, for optimum sound, dont pay attention to this number. What you need to do is have your woofers above the floor by about 2-4 inches. This should give you some awesome sound. You will need to design the box a little different but you need to suspend your woofers about that much from the floor.

 

hmmmm 2-4 inches....woofer has a mounting depth of 5 inches. If I give the cone about 2 inches....cone pokes out about a half inch when top mounted leaves it 1.5 inches from the floor. Give the back of the speaker 1 inch from the top of the box for some breathing room. Factor in 3/4mdf and the box would have to be 8.75 inches tall. The seat is only 7 inches from the floor. I guess Il need to lift the back seat a couple of inches

 

As long as your surround on the woofer does not hit the carpet at full xmax, you are fine. The Qlogic box only sits the woofer off the ground maybe 1/2" but, the surround never touches the carpet. 2"-4" would be hard to achieve under the seats. The MusicMoose box I had actually set the surround right on the carpet. But, when it played, you could hear it flap against the carpet. You just need enough to avoid touching.

 

Xmax is one way linear excursion. If you have less than a 1/2" of Xmax and your sub's cone/surround sticks out from the baffle about an 1/2"....then you theoretically, you should be good with just 1" from baffle to floor. Would I go with that? No, 1.5" if your tight on room and at least 2" if not.