hey, i thought id take a few minutes to explain the resistance calculations and ohms from the question you had about it.

Ohms is a measure of resistance in a circuit. The greater the value of Ohms, the more resistance that is present in the system. For example, when an amp has a 4 ohm load it puts out half as much power as it does when it has a 2 ohm load. This happens because the amp has less resistance or the power has less "junk" to flow through so it can flow easier and in greater amounts.

As far as calculations go, they are fairly easy as well....
When we discuss calculations we need to understand two main types of wiring setups: Series Wiring and Parallel Wiring.

Series: A series circuit exists when two or more subs are connected in a string, end to end, so that only one common terminal is shared between components and they share the same current.

To calculate the total resistance if a series circuit, all youhave to do is add the numbers of the resistances of each individual sub together:

Let's say we are wiring 2 4ohm subs in series.....
Resistance 1 or R1 = 4ohms (the resistance of one of the subs)
Resistance 2 or R2 = 4ohms (the resistance of the other sub)
Resistance Total or Rt = 4ohm + 4ohm = 8ohm.

Parallel: A parallel circuit exists when two or more components are connected so that two terminals are shared between components and voltage is common across the shared terminals.

To calculate total resistance of a Parallel Circuit w/ 2 speakers connected the formula is:

Rt = (R1*R2) / (R1+R2)

For example if we have two 4ohm subs wired in Parallel....
our R1 = 4ohm
our R2 = 4ohm
our Rt = (4ohm*4ohm) / (4ohm + 4ohm) = 16/8 = 2ohm.

If more than two speakers are wired in parallel we need to figure that into the total average resistance, the formula is a little different:

Rt = (1 / (1/R1) + (1/R3) + (1/R3) + ...)

Now these same formulas apply to DVC subs. Let us say you have a 4ohm DVC sub. We consider the R1 and R2 to both be equal to 4ohms. Now you can wire it either in series or parallel and calculate the overall resistance in ohms of the circuit. I hope this helps, feel free to IM/PM me w. any more questions.