I am going to put in a mulitzone system and in one of my zones there will be 4 pairs of speakers. Speakers are normally 8 ohm but I know by hooking up more than one pair I'm dropping the impediance (i think that's correct). I don't understand what that means in practical terms, though. I plan on using a separate amp for this zone but I don't know how much power I'll need or what else I have to do because of running 4 pair of inceiling speakers in this zone. Explanations and all advice welcome. Thanks

Individual speakers have a rated impedance which simplified is nothing more than resistance to the 'flow' of current. Impedance in your speakers is actually made up of two parts, the resistive and reactive portions. What you need to be concerned with is the application of paralleling two or more speakers on an amplifier output from a receiver or similar device.

If you have one speaker with an impedance of 8 ohms and your amplifier has the ability to produce 16 volts across the speaker, the current through the speaker will be 2 amperes or 16/8 =2. Now if you add a second speaker in parallel, you will try to produce that same 2 amperes through each of two speakers. Essentially, making the speaker look like a 4 ohm impedance. Now the amplifier has to provide 4 amperes of current to drive the two speakers to a similar output or 16/4=4. The amplifier has to work much harder to do this and in some instances can overheat or become damaged. Adding additional speakers in parallel to the same output will only cause additional problems. This is why we use amplifiers which are made for this purpose.

You will probably need to add additional amplifiers or equipment to drive the speakers in a system such as this. You can probably drive two sets of speakers with the same amplifier outputs if the equipment is rated for 4-6 ohms output impedance, but I would not try to drive three to four sets this way.

You could use a series-parallel connection.

Assuming a stereo config (8 speakers, 4 per channel) you should be able to stay at 8 Ohms impedance using a series connection of two parallel arrays.

In other words, connect the speakers in two parallel pairs then connect those parallel pairs in series for each channel.

You could use a series-parallel connection.

Assuming a stereo config (8 speakers, 4 per channel) you should be able to stay at 8 Ohms impedance using a series connection of two parallel arrays.

In other words, connect the speakers in two parallel pairs then connect those parallel pairs in series for each channel.


That is a possibility, however, now each speaker will use about half the original power (with the same amplifier output = much less volume) and you may have other audible problems.

Take a look at this page I found. Series Parallel Speaker Impedance (http://www.bcae1.com/spkrmlti.htm)

It's a little more geared for car audio but the same principals apply. It uses a lot of lame car analogies to explain but it is a fairly decent explanation.

That is a possibility, however, now each speaker will use about half the original power (with the same amplifier output = much less volume) and you may have other audible problems.

Sure, each speaker will use it's fraction of the power, but you also have that many more speakers producing sound - will the overall level be that much different?

If you have (for example) two speakers fed with 100 watts, and now put eight of these same speakers in a series-parallel arrangement each now receiving 25 watts, what is the result? The amount of "power" going into the room is the same in each case, yes?