Audio Systems: systems, ohm load, 4 ohms

Question
i have 2 15" audiobahns. they each have a dual 4 ohm voice coil. does both of them combined equal into a 4 ohm amp, a 2 ohm amp or a .5 ohm amp??? which one do i need??

Answer
If you connect the coils in parallel it will give you 2 ohms.  If you connect them in series it will give you 8 ohms.

If you have only one speaker connected to an amplifier output you should connect the coils in parallel and use an amp that has stereo outputs that will feed a 2 ohm load.

If you are using an amp in bridge/mono and are wiring two speakers to the one amp output you should wire the coils in series (for 8 ohms) then put the two subs in parallel for a load to the amp of 4 ohms.  However, if you know for certainty the amp will drive a one ohm load safely (not many amps will do so, by the way) then you could put all the coils in parallel for a one ohm load to the amplifier.

Is it clear?  Let me know if you don't understand any part of it.

Cleggsan