What tools and methods do I need to calculate my imp rise. 1 15" AA SMD, Sundown saz 3000d. 4^3 @ 31hz, 30^2 port area (I know way to small, just testing an aeroport). Sub wired to .75 ohm Just got a clamp meter today and messing around I did 18.4 amps & 79.8 volts @ 37hz. I want to know what the impedance is doing but not exactly sure how to check for that Thanks