Speaker Impedence Mis-Match Question

[dcgee27]

I'm setting up a home theatre in my basement and plan on using 7 ceiling speakers plus two subs. I'm using polk TC60i's for all of my ceiling speakers except the center channel which I'm using a polk LC80i. The TC60's are all 8ohm speakers and the LC80 is a 4 ohm. Is this ok? Are there any special things I need to be aware of with this setup? Am I better off just putting another 8 ohm speaker for the center?

Thanks very much!

 

[peterL]

Well, there are a couple things at play here. First, if the amp can drive a 4 ohm load, then there is no problem. Just set the levels correctly.

Impedance ratings can be a little misleading. The impedance of a speaker varies with frequency. My PSBs have a max impedance of 16 ohms at ~1.5 kHz and a minimum of 4 ohms at around 150 Hz. PSB rates this speaker as having a "nominal" impedance of 6 ohms. It seems that different speaker companies have different ways of settling on this "nominal" impedance.....

Long story short, if you have a decent amp, this shouldn't be an issue. If you don't, there could be overheating issues or even shutting off at high volumes.

 

[Exit]

Ceiling speakers for the front, left, center and right speakers may result in the sound being perceived as comming from the ceiling instead of the video screen. You will be happier if you either use in-walls or stand alone speakers for the front channels. The speakers should be located at seated ear height radiating in the horizontal plane. The side and rear speakers are not quite so location sensitive and can be used effectively in the ceiling. Thought someone should mention it.