Confused about ohms...

[Sammitch0]

Nothing pisses me off more when I go to install someones woofers and I have to use the12volt.com to find ohms etc. for subwoofer wiring. It's even more of a pain in the ass when Im not internet accessible. Is there a printout chart or a mathmatical was to figure out how many ohms your running and if its series/parallel etc.?

I want to be able to do this in my head but the math for EVERY wiring way is different, and theres tons of them: Series & Parallel, Series/Parallel, Parallel/Parallel, Paralell/Series etc, etc, Ive tried to make sense of it all but I can't. Can anyone tell me the math to figure out ohms and how to know if you're supposed to do it in parallel or series? up until now this Is the ONLY thing that has stumped me and one of my biggest problems.

[Berto]

How I remeber it is you either add the ohm to itself or divide it by itself.

Example:

Dual 2 can either be 4ohm or 1ohm, so it'll be 2+2= the 4ohm load or 2/2= the 1ohm load.

[Skullz]

It's easier if you write it out the first few times till you can get to the point of it becoming second nature. Start out with each sub as it's own and then combine more and more till you get to where you want to go, so say you have 2 D4 subs and want to get to a 1ohm load all you have to do is parallel the first sub since it will drop the ohms down to 2 ohm and then do the same thing to the second sub so now you have each sub at 2ohms and then connect them in parallel down to a 1ohm load.

Series = Doubling the ohm load - would look like D4 + D4 = 8ohm

Parallel = Halving the ohm load - Would look like D4 + D4 = 2ohm

[fr34kout]

Adding on to what he said, when you wire in parallel you drop the ohm load in half. When you wire in series you double the ohm load. When you're dealing with multiple subs do it in steps. So say you want to wire 4 D4 subs together to 1 monoblock. Each D4 sub can be wired to 2 ohms on it's ohm when you run them in parallel. Then you can wire 2 of these 2 ohm subs together in parallel again to get 1 ohm per pair of subs, Then you can wire the 2 pairs of subs together in series to get back up to 2 ohms, or in parallel to drop down to half ohm.

[Sammitch0]

Ok I think I get it the12volt.com made it so damn confusing... Question how does D4 + D4 = 2 OHM if you havling them wouldnt it be 4 OHM? or do you do 4/2 + 4/2 = 4 then divide that by 2 and you get 2? since it's two woofers? If not im confused on that one...

[fr34kout]

Ok each coil on the sub is 4 ohms. D4 means Dual 4, so there are 2 voice coils on the sub, each one is 4 ohms. When you wire the two voice coils together in parallel you get a 2 ohm load for that 1 sub woofer. If it was a SVC (Single Voice Coil) 4 ohm sub, it is just straight 4 ohms.

[Sammitch0]

That wouldn't be parallel thought that'd be Series/Parallel which means Series on the coils and parallel on the subwoofer. This is also what confused me... How do you know when its acceptable to bridge the coils and when its not? cause you could technically bridge ANY DVC woofer but on the12volt.com it shows only curtain combos can be Series/Parallel not just any subwoofer.

For instance 2 x 4OHM DVC parallel/parallel is 1ohm but series parallel its 4ohm i dont get that? how do you know when you can do series/parallel

Oh I c... when you add another woofer it drops the ohm load in parallel so 1 4ohm DVC is 2 OHM parallel and add another you get 1 OHM... ok so parallel is pretty damn easy, series is where I get confused.

Edited November 24, 2010 by Sammitch0

[Skullz]

Use this a few times with different numbers of subs and different ohm per coil configurations so you can see exactly whats going on.

http://www.rockfordfosgate.com/rftech/woofer_wizard.asp

[BanginOnABudget]

i still dont get how 4 8 ohm subs in series is 3 ohms. shouldnt it be 1 ohm?

[Guest]

i still dont get how 4 8 ohm subs in series is 3 ohms. shouldnt it be 1 ohm?

http://www.the12volt.com/caraudio/woofer_configurations.asp?Q=4&I=81#results

only 2 and 8 ohms for 4 svc eight ohm woofers.