is it possible to have a box where you could tune the hertz to whatever you wanted to after you already made it, perhaps with a switch on the head unit. it would probably have to be some kind of electric box with moving parts. is it possible though?
I just had a brainstorm. What if you made a port telescopic. This would mean that if you hooked up someking of motor to make it move in and out then you could adjust it that way. Find out how long the port needs to be for different Hz tunes and then use the telescoping port to adjust to your desired Hz setting at that point in time. It would basically be like a re-tracting car antenna but bigger in diameter, catch what i am saying?