i am looking at amps and they have a rms power rating at 2 ohms and 4 ohms. the 2 ohm is always higher, and looks to be the cheaper way to go for more power. Can I run any subwoofer at 2 ohms? or does it have to be specific for 2 ohms?
You're talking about the impedance on the sub's voice coils. The impedance determines how much power the amp will send to the sub. A 2 ohm load is effectively twice as hard to push for the amp, but you will get double the power out of it when compared to a 4 ohm load. www.bcae1.com
Depends on the sub. If you have a single voice coil sub that runs at 2 ohm, then yes, you can run in 2 ohms. Also, if you have a dual voice coil sub with 4 ohms per coil, then you can also run in 2 ohms, by wiring them in parallel. If you have more than one sub, then you can also run in 2 ohms by having 2 single voice coil 4 ohm subs, or with 2 dual voice coil subs that have 8 ohms per coil or .5 ohms per coil.