Question, I have a fairly large speaker box with the 18" sub pointed up in my SUV, the port for the box is facing the flip up door in back, it is only about 12 inches or less from the door, would putting something like plexiglass on the back door where the port hits the door work for a better sound, I don't have the room to move everything around, as I am using 3 amps, lots of wires. Any suggestions would help. Thanks
the only thing i can think of is to deaden your back hatch. but that will just take away noise form the back and will make the sub appear louder and help energy transfer. (i reserve the right to be wrong.)
our vehicles we drive were not designed for all of the torturous spl we here at ecoustics place in them. So you are probably going to have to reinforce your back hatch with the sound deadening material of your choice one of these nice summer weekends when you get time ( x2 deathoob).
12" from the back hatch is just fine. Your hatch may rattle to hell and back, but its fine as far as distance.
In fact, in many cases...having your port even closer to the back hatch is better. That will load the port and make the box tune lower than its 'on paper' tuning frequency.
A rule of thumb (that doesn't really work in many cases, but is something to think about...I.E,..take it w/ a grain of salt) is to have the port at least the same distance as the ports width from any structure in the vehicle.
When designing a box, you have to take this vent loading and vehicle transfer function into account. That is why quite a few of the boxes I design 'tune' in the low 40hz range, but still SLAM at 30hz
Post pics and measurements of your box if possible. If your back hatch rattles really bad and you want to stop it, mat it w/ at least 2 layers.