I have a Sharp 5.1 speaker system. The original speaker has a rated input 50W, 100W max input, 4ohm impedance. I would like to replace these speakers. What kind of rating/impedance should I choose? Does the original amplifier work with 8ohm speakers? How about the 150W speakers?
You gotta get 4 ohm speakers if that is what the amplifier is rated for, otherwise you risk an impedance curve that can overheat your amp or blow out your speakers.
Fork over the $200 dollars and buy a new receiver as four ohm speakers are generally harder to find unless you buy car speakers. Also that Sharp itself is only rated for 50 watts which is kind of weak for most home theater discussion. It came as part of a box set so it's probably high on total harmonic distortion just at 50 watts at four ohms. If you were to increse the resistance to eight, you'd probably get about 25 watts on it and you're looking at atleast a 5% THD. Don't risk blowing your new speakers. Just get a new receiver.
Almost all amplifiers will work with 8 or 4 ohm speakers. The wattage rating refers to the amount of power that the speaker can handle. Having a higher wattage than your amplifier is fine, it just may mean the speaker is less efficient. Having a speaker that is rated lower than your amp is usually fine as well, just don't turn it up all the way.
You can use 8-ohm speakers; amps will tolerate higher-impedance speakers without problems. However, the maximum power output will be reduced. Unless you need a lot of power, this is not a problem either--just turn up the volume a little. Use speakers of equal or higher power rating than the originals.
