sub and amp impedance matching

if my amp can output either at 2 ohms or 4 ohms and my sub is 3 ohms, how do I get this to work? will the amp work ok or have problems such as getting hot etc? Or should I attach a 1 ohm resistance in series with the sub to make it 4 ohms? Not sure as to what is the best/most efficient way to do this. thanks.

This all depends on the type of amplifier that you have. On most 2 channel amplifier you can bridge them at 4 ohm combining the left and right channel to give you the maximum output. On a mono block amplifier the most efficient output is usually at 2 ohm and some even at 1ohm.   To answer your post, the best and safest way to run your 3 ohm sub is to run it at the output of your amplifier where you said 2 ohm. If you run your sub at the 4 ohm output of your amplifier it will be less stable and can over heat overtime and be damage. The best rule of thumb is stay within the amplifier specification, which the engineer had designed it for.      Be careful whose advice you buy, but be patient with those who supply it.

DYohn wrote: Your amp can handle any load DOWN TO 2-ohms.  3-ohms is fine.  Adding a resister is never, repeat never, a good idea.

Thanks. I thought its a bad idea but just had a (bad) thought. Now that I hear it is ok, I'll just use it without fear of burning out anything.

thepencil wrote: To answer your post, the best and safest way to run your 3 ohm sub is to run it at the output of your amplifier where you said 2 ohm. If you run your sub at the 4 ohm output of your amplifier it will be less stable and can over heat overtime and be damage. The best rule of thumb is stay within the amplifier specification, which the engineer had designed it for.

My amp says that it can run stable at 2 ohm and 4 ohm. It also says that it can give an output of 250watts at 4ohm load and 500 watts at 2 ohms. So like you said, I will stay withing the specifications. Thanks.