Look! Subs in parallel ohms formula

I'm sure this is on this site somewhere but recently I've seen a few posts about subs in parallel and DVC's and all.  I thought this would help.

If you want to figure out what ohm load you will have when subs are wired in parallel, and assuming that all subs or voice coils(SVC's have one, DVC's have two each) are the same ohm load(when using two or more, they should be) then use this formula:

Resistance = R/n 

That is the resistance value of one voice coil divided by the total number of voice coils you have. 

Example 1.  two 4 ohm subs in parallel.  4 divided by 2 =2 so you have a 2 ohm load

Example 2. three 4 ohm subs in parallel.  4 divided by 3 = 1.33 so you have a 1.33 ohm load

Example 3. two DVC 4 ohm subs with all coils in parallel.  4 voice coils total so it's 4 divided by 4 = 1 so you have a 1 ohm load.

You could also wire the coils of each DVC in series, which is just one end of one wired straight to the end of the other one and make an 8 ohm sub out of each.  Then wire each woofer together in parallel and get a 4 ohm load total.  The math is the same.  In series you just add it all up so each sub is 4 ohm + 4 ohm = 8 ohms.  Then in parallel it's 8(ohms of one sub) divided by 2(two voice coils) = 4 ohms total.  There are really four coils, two on each sub, but we wired them in series making the two into one.  So we do the math as just two voice coils.

As for series wiring, it was already stated.  Simply just add them all together.  But in car audio, we don't do a lot of series wiring.  Mostly parallel.

I figure this post will last about a day or so until the ones that were asking are thru with their projects.  After that it will go on to page 2 and 3 and 4 and......forever.

This could help too!!

https://www.the12volt.com/caraudio/boxcalcs.asp

That's good, but assumptions have to be made (all subs identical).  And series/parallel wiring gets confusing with this.  Once the coils are wired then the sub should be treated as a single impedance load to keep calculations simpler.  Here is a formula DYohn posted several months ago that I have been using:

The equation for parallel wiring is 1/Rtotal = 1/R1 + 1/R2 + 1/R3 etc ...  The equation for series wiring is Rtotal = R1 + R2 + R3 etc...

Good input, audeo.  Glad you decided to stick around.