No real was to calculate it without actually building the box and testing it in your vehicle. The same box/subs will actually see different box rise in different vehicles.
design, build, test, tweek, design, build, test, tweek, design, build, test, tweek, design, build, test, tweek, design, build, test, tweek, on and on and on.
box rise happens @ certain frequencies & is directly related...
to calculate ur impedence rise you must measure your ac voltage output on the speaker terminals... record that.. Next measure your ac current, you can use a clamp meter on 1 of the speaker wire leads, or u can series a dmm between the + terminals and the speaker + wire... (always measure current in series) record current
now calculate your AC impedence (Z) which is the equivalent to DC resistance (R ) <<see how simple its is impedence and resistance same thing. lol V= voltage I= current
formula Z = V/I ^^that means divide the current into the voltage...
Impedence is the actual resistance your amplifiers will see from your sub.
Too add....even distance of the port from the rear deck lid will effect impedence rise, as proximity to the gate effects loading, which effects, resistance, which directly effect rise.
As will the wire you use. (Resistance) (Wire is wire eh?...Yea,.... ok.)
To prevent? A better sub, or a better box.
As for helping by inverting? Since a larger enclosure lowers tuning and tuning effects rise? Maybe. Were well over my head here.
