How does the impedance rating of speakers effect thier performance?

Question

Two of my four surround sound speakers are rated at 8ohms and the other two are 6 ohms, can I use all four on the same stereo?

Answer 1

As long as you are not hooking them up onto the same channel you should be fine.  Receivers are usually rated for 4-8 ohms per channel.  In terms of performance, one is not better than the other, but there may be a difference in volume output level, so if using two different pairs of speakers with different impedance, you may need to adjust the channels to compensate.

Answer 2

There is not enough difference between 6 ohms and 8 ohms to matter to your amplifier.  Speaker impedance has no relation to speaker quality.  There are 16-ohm speakers that are outstanding, and there are 4-ohm speakers that are also outstanding.  The only thing you can't do is connect two different impedance speakers to the same amp output (either series or parallel*); if they are going to different amp outputs, you will be ok.

In other words, your stereo must have an output for each of the speakers.

*Additional detail:  if you connect them in series, you will get 10 ohm total which almost all amps can handle without problems.  However, the 8-ohm speaker will output most of the sound; the 6-ohm speaker will contribute very little.

If you connect them in parallel, the load on your amp will be 3.4 ohms, which could cause the amp to overheat.  Even if that did not happen,  the 6-ohm speaker would dominate the 8-ohm one.

Answer 3

The higher the impedence, the greater the load on the amplifier, thus less output. Impedence generally affects the frequency response of different size speakers. Tweeters usually have higher impedence> 8 - 16 ohms, while woofers are usually rated in the 4 - 8 ohm range. Some woofers may only require a 2 ohm load and will drain the life  out of (kill) most amps. The 8 ohm speakers you have will probabally exhibit a stronger midrange to high end, while the 6 ohm speakers will probabally have a less lively top end, and the midrange will extend a little lower than the other speakers. The 8 ohm speakers will be less efficient (not as loud) than the 6 ohm ones. The 8 ohm ones will require more power (watts) to acheive the same loudness as the 6 ohm speakers. It is also imperitave that your amplifier can deliver (be stable) its rated power into a 6 ohm load, as many amplifiers are rated at 8 - 16 ohms! If it is not stable at 6 ohms, it may overload your amp, and burn it up!

Answer 4

It's not ideal to mix speakers from different brands as it blows the illusion of surround sound.

But yes, it will work.

Get a Radio Shack SPL meter and a copy of "Avia" or "Digital Video Essentials" and use the test-tones to adjust the volume of all the speakers so they produce the same volume in your chair.  Likely the speakers have different efficiencies so this calibration step will compensate for the differences.