Need help selecting stereo receiver, impedance??

[JasonF]

So I bought my house a couple years ago which was built in 05. The original owner when the house was build put 8 stereo speakers in four different areas so the living room, kitchen, hallway and master bedroom each have two ceiling speakers. The speakers were never wired to a receiver so now I'm tying to figure out what to buy to get this set up correctly.

I pulled one of the speakers out of the ceiling and found that they are 75 watt 8 ohm Proficient c605 speakers. My thought is that I would like to put a very basic 2 channel receiver in a small closet I have mostly to play music over Bluetooth from a phone or tablet. I was thinking about pairing the receiver with a 4 zone (2 speakers each zone) speaker selector so that I could select all or only some of the rooms.

My question now is what watt size receiver do I need to buy and how will it be affected by how I wire the speakers into the selector and receiver? Its my understanding that if i had a 2 channel 8 ohm receiver that it would essentially power two speakers at 8 ohms. Now if I use the 4 zone speaker selector and have all the speakers on, isn't that the same as wiring all the speakers in parallel and now creating a different impedance???

I also was wondering how wattage is divided? So theoretically if I have a 2 channel 200 watt receiver, would that mean each channel would get 100 watts and then in my case with 4 speakers on each channel then each speaker would only get 25 watts??

Any input is greatly appreciated.

 

[Just_George]

You will need to install some sort of impedance-matching device. We used to use a few different ones - on the low end of the scale were simple little transformers that were wire-nutted to the speaker wires. At the high end was a piece (forget the mfr) that had much bigger transformers and nice buss strips for attaching the speaker wires. Niles Audio also makes some units that include separate volume controls for each remote pair of speakers.

In any case, your 8 speakers look to the receiver like a single 1-ohm load. Without some kind of impedance matching, your receiver will work too hard trying to drive that load. Impedance matchers have multiple taps that allow you to compensate and make the load look like 8 ohms at the receiver.

For 4 pairs of speakers, I think you want a receiver with 100 watts of power, minimum.

 

[dcmus]

You will need to install some sort of impedance-matching device. We used to use a few different ones - on the low end of the scale were simple little transformers that were wire-nutted to the speaker wires. At the high end was a piece (forget the mfr) that had much bigger transformers and nice buss strips for attaching the speaker wires. Niles Audio also makes some units that include separate volume controls for each remote pair of speakers.

In any case, your 8 speakers look to the receiver like a single 1-ohm load. Without some kind of impedance matching, your receiver will work too hard trying to drive that load. Impedance matchers have multiple taps that allow you to compensate and make the load look like 8 ohms at the receiver.

For 4 pairs of speakers, I think you want a receiver with 100 watts of power, minimum.

I agree with Just_George. I'd opt for at least 400 watts to optimize your speakers. You can always turn it down

 

[Will S.]

Understand that some manufacturer's use peak power out, which is not very meningful, and others use RMS power. RMS means average power, and is the real rating of the amp.

For what you want to do (home audio dist), at normal background music levels, you won't need hundreds of watts per channel, but if you want to crank it up in all the rooms, then you certainly need more. Chances are that you only need 10-15 watts per speaker, times the number of speakers that will be driven simultaneously, at a comfortable listening level.

For speaker selection and volume control, buy one of these. They come in 2 channel, 4 channel, and you can pair them up in a rack-mount config, for as many speakers as you need, or you can buy individual wire-wound speaker volume controls, like we put in restaurants hotels. Here's a good place to start:
http://www.monoprice.com/Product?c_id=109&cp_id=10903&cs_id=1090307&p_id=8232&seq=1&format=2
http://www.monoprice.com/Product?c_id=109&cp_id=10903&cs_id=1090307&p_id=8231&seq=1&format=2
http://www.monoprice.com/Product?c_id=109&cp_id=10903&cs_id=1090304&p_id=8235&seq=1&format=2

 

[Catadj78]

http://www.eminence.com/support/wiring-diagrams/

Some recievers have channel selectors allowing you to turn on/off certain rooms. It has been a very long time since I dabbled in stereos and then it was car stereos. Match the ohm load to the receiver

 

[Ragtop13]

I have 3 listening areas on my main amplifier:
the main TV room
The back patio
and the garage

I used a monoprice speaker selector to switch the speakers.

My pioneer has 2 audio zones. Zone 1 goes to my main tv room. Zone 2 is hooked up to the monoprice speaker selector. With the speaker selector i can have both the patio and garage on or select one or the other. I also installed the impedance matching volume control in the garage and patio.

Most amps have a minimum impedance rating of 4 or 6 ohms. The monoprice speaker selector keeps it around 5 ohms minimum regardless of how many speakers you have connected to it.

I used the 8 channel simply because it has a higher power rating.

http://www.monoprice.com/Product?c_id=109&cp_id=10903&cs_id=1090305&p_id=8230&seq=1&format=2

The volume control.

http://www.monoprice.com/Product?c_id=109&cp_id=10903&cs_id=1090304&p_id=8237&seq=1&format=2

With this you don't have to worry about parallel-ing or series-ing the speakers..... hook them up and go....

 

[James-W]

Depending on how far the speaker wires need to be run, you may want to consider a receiver that is 70 volt line (speaker system) capable. If you aren't sure what that means, just Google it and you will find an explanation as well as pictures and it will be explained much better than I can do it.

 

[jgorm]

Any regular receiver will work. Home based stuff is 8ohm, car based stuff is 4ohm. If you just hook one speaker to one port on the amp, then you will have no issues. I've run 4ohm (2 8ohm speakers) loads on home speakers without issues on lots of different amps.

 

[JasonF]

Thanks for all the input so far, this all makes more sense!
I am considering using this speaker selcctor that was posted above;
http://www.monoprice.com/Product?c_...&utm_medium=11051853&utm_term=VigLink-2470763
The question I have though is on the max channel wattage for this unit? Is the 100 watt max the most that the speaker selector can receive from the amp or is that the most it can send out through each of its own four channels? If it's a 100 watt max from the receiver/amp then wouldn't that only equate to 12.5watts for each speaker?