I have heard that vehicles in particular change tuning on boxes in the overall sound output, the biggest factor being how far the port is from the rear or anything that can obstruct the flow of air. Im trying to figure out how low my overall sound will be tuned to with the box, its 40hz design with around 90sq. in of port for each sub, and the port area is at the bottom of the box goin across, not the middle going up and down like most boxes, it is placed about 3 inchs from the rear at the moment, will this lower the tuning and how much? Im trying to figure out if i can change the tuning of my box just by the positioning, like 7inchs from the rear should be my peak SPL from this box i believe
whats the dims of the port? they say, for a round port anyway, the port should be atleast the distance of the radius away from anything. but it can be different if its a 30x3 port, 3 inches could work better but still, 3 inches isnt very much.
all depends on the car..... sometimes its juzzz a 3 hz drop from the original box tuning sometimes its less sometimes its more....
it really depends on your car... the size the shape etc....
well at the time you drop your box to your trunk or car.... it acts like a bandpass box... u juzz dont juzz build an "x" box.... u built a box that can interact with your car.... ( u know build the port firing somewhere the sub up or firing back the shape of the box so it can fit in yoru ride etc...)
thats why in car audio there is no "one size fits all" subwoofer enclousure....
thats why u have to think about your car when your building your box... like i i said think about your car its a bandpass enclousure... the area where its port its your box... and the area where its sealed its youcar interior... sometimes there are bandpass that have two areas that are ported u can use it too as yoru box one part that its ported and your car the other part....
if u tuned yoru box as a daily driver u should not worry about tuning drop.... since it will not be a BIG deal except if ur a competitor and numbers its that u care about.... look yoru box its tuned at 40 hz with tuning drop the max u can get its around 36 thats i think the max i seen in alot of cars... but it takes alot to drop from 40-to 36hz.... but your car or i mean truck it will drop to 38hz juzz 2 hz its not a big deal so dont worry about it...
The reason i think it will be a bigger effect with my box is because the ports go across the bottom of the box, they are 4x18 openenings. The top of the port area is still about 19inchs down from the top of the box so the air actually has to travel further to get into the BIG area of free air. so in reality if the whole idea of the radius of the port thing is acurate just going by the smallest i would want 4 inchs... i only have 2, maybe 3 at most. I planned it in a way but all that much, i want to make it loud and still sound decent and still be able to make it sound good and low with just moving the box instead of changing ports.