Box f3

[Daddy_]

Im looking to run a alpine x 12" sealed. Alpine recommends 0.4 to 1.25 sealed range. They also have a specific sealed box that's 0.85ft3 with a f3 of 36 hertz. From what I understand the f3 is where it's starts to roll off slowly -3db. So if I wanted to have the f3 roll off around 30 to 32 hertz how much would I have to increase the box? Was originally going to do 2 or 2.5ft3 but what like to save space in my trunk. Is there a formula to get f3 with bigger box? 

[ckeeler11]

Cabin gain will affect the F3 so you will need to know the how your vehicle impacts the response. If your F3 is 36 Hz then you will be quite a bit below that in real life.