i have an alpine sbs-084bp (8" 4ohm in bandpass box). how do i find out what frequency its tuned too so i can properly set up my amp, or does it matter?
actually bandpass boxes are sealed in the back so no sub-sonic is needed but could still be useful. However a lot of bandpass boxes especially have weird freq. response that peaks big time between 40 and 50 hz. If you are going for sound quality tweeking the crossovers may flatten your response out to some degree.
There are people on this site that could calculate it for you. What are the dimensions of the box. You need to be very specific such as the sealed chamber's volume, the ported chamber's volume and also the number of ports, diameter, and length of the ports.