What is the difference in 4 and 2 ohms in a subwoofer?I was looking at getting a jl audio w3 but not sure of which one i should get.

 

What amp will you be using to power the sub.

 

As jbullerjr asked, much of that will depend on your power output of your amplifier. If you get a momo block amp, you will get more bang for your buck with a 2 ohm single sub, as long as its (stable rated at 2 ohm). Four ohm subs are pretty standard these days. Most people push two subs off of one amp. When two four ohm subs are run together in a standard configuration, it will drop your total ohms down to two ohms. Three subs, 1 ohm and so on. If you only plan on using a single sub, get the two ohm JL. If you decide you want to run two later, make sure you by a 1 ohm stable mono block amp.

Amplifiers normally will have there specs available. One reading at its lowest stable consistant output. one at it max peak output (often BS). And another at a specific rated ohm. Example- 400watts 4ohm, 600watts 2ohm, 750 1ohm, 850 max output. Make sure your amp and sub match with a costistant amount of power by choosing your sub or amp first, then finding the best product to compliment your needs.

 

Just to add to what BrickWurX said. When you get an amp even if it says that it is 2 ohm stable this does not mean that you can turn the gain near the max and run the amp with a 2 ohm load at high volumes for long road trip without have some kind of additional cooling for the amp. Many companies over rate there products. They say 2ohm stable simply because the amp will run contiuously with a 2ohm load but forget to menton that the amp will over heat and shutdown or blow a fuse. If you don't mind spending just a bit more cash buy a bigger amp and run it at a 4 ohm load and you will never have to worry about it over heating. Also it makes a big difference if you are looking to get a single or dual voice coil sub. Dual voice coil sub allow for more wiring configurations. Example: I am running 2 12inch Kicker Solo-baric L7 squares with a mono block 1500 watt amp. This amp pushes 750 watts at 4 ohms continuous or 1500 watts at 2 ohms. The subs are 4 ohm dual voice coil. I have them wired with the voice coils in series and the subs in parallel to the amp. This allows me to get 750 watts to each sub still on a 4 ohm load to the amp. I have taken a 4 hour road trip and the amp was only slightly warm to the touch.