Originally Posted by

**Reffc**
This is not quite correct Ken. Hooking up two loudspeakers to the same amplifier output puts both pairs in parallel, so the amplifier sees a load equivalent to the two sets of impedances in parallel. If those loads are nominally 6 Ohm in the bass, then the minimum impedance can be less than this...down to 4 Ohms even, so the amp could well see a combined 2 or 3 Ohm load. Not a good idea.

3 way speakers may have current demands at varying frequencies that occur all at once, but hooking two pairs up is different because you're presenting two bass unit plus two mid unit impedance to the amp at once, per channel, unlike single channel 3 way systems, with the current loads that would demand. Also, the crossovers in between the drivers for 3 way systems means that you are splitting the frequencies so worst case for a "nominal" 6 Ohm load would be a "nominal" 6 Ohms! (or 4, or 5 or whatever the lowest case might be) and NOT the summation of the parallel loads of all three or more drive units.

Impedance will rise with frequency, but it matters less at higher frequency if you get a lowish impedance, as current requirements are less. It's the low frequencies all the way up to 1 or 2 KHz that demand most current. Combine that with difficult phase angles, and it could be a recipe for a blown amp.