Impedence matching setup (amateur content) - AVS Forum
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post #1 of 7 Old 06-24-2011, 01:20 AM - Thread Starter
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Hi all,

Firstly please excuse my obvious lack of knowledge as I am still very uneducated in the world of audio (as I tried to warn in the title).

Anyway, I am looking for some advice in setting up a three room sound system with a reciever in the middle room and a pair of speakers in each of the three rooms (three pairs total). I have been planning on connecting a stereo receiver to the three pairs of speakers with some sort of impedence matching and also volume controls, but I recently read some contradictory info on sound quality when using an impedence matching setup and have not been able to find out any more info. I'm not talking any audiophile-esque issues here but i basically want to make sure I am chosing a "decent" setup for my new Klipsch RF 52 II's ($700 to give an idea).

Does anyone here happen to have any insight or experience with these kinds of setups? I am wondering if I might be better off getting a 5.1 reciever to give the Klipsch speakers in the main room their own channels and then connecting the other two rooms off the surround channels with impedence matching (since I don't care as much about sound quality of the bookshelf speakers in the other rooms). Does that make any sense at all? Any thoughts?
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post #2 of 7 Old 06-24-2011, 09:35 AM - Thread Starter
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on a related note would I just divide the wattage by 3 to estimate each speaker's power, or with impedence matching am I dividing wattage by 6...
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post #3 of 7 Old 06-24-2011, 11:23 AM
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Power = Voltage^2 / R so it depends upon the impedance (R) of each speaker. Note the impedance can vary a lot over frequency, so you may end up with strange sounds. You'd also have to figure out a design to keep the impedance at the amp high enough when driving three pairs of speakres. Not all that hard, but potentially wastes power, and your question indicates circuit design may be a stretch. I would just get the 5.1 system, or any system with secondary (Zone 2/3) outputs, or perhaps use a second power amp for the other rooms.

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post #4 of 7 Old 06-24-2011, 12:06 PM
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It sound like your trying to make this more difficult then it needs to be. A 5.1 receiver wouldn't be enough unless you do it the hard way.

Get a 7.1 receiver, put your speakers where you want and run the speaker wires.

One room will be from the left & right channel
Another room will/or can be your left & right surrounds
3rd room will/or can be your back surrounds.

To have them all pay the same, just select All Channel Stereo on your receiver. This way, you don't have to worry about Impedence.

I believe there will be a few others sound fields you can select, depends on your receiver.
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post #5 of 7 Old 06-24-2011, 04:14 PM - Thread Starter
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Thanks for the replies.

"Power = Voltage^2 / R so it depends upon the impedance (R) of each speaker. Note the impedance can vary a lot over frequency, so you may end up with strange sounds. You'd also have to figure out a design to keep the impedance at the amp high enough when driving three pairs of speakres. Not all that hard, but potentially wastes power, and your question indicates circuit design may be a stretch."

I forgot to mention that the speakers will all be 8 ohm units. Thanks for the info on how the impedence might vary, thats pretty much what I was looking for. I found a unit that is rated to +/- 2 dB across the spectrum which I could use for the main speakers, but it just seems like inserting an unneceassry component in the chain at the end of the day. As far as designing the circuit I was thinking something along the lines of a switchbox or volume control with impedence built in (since I need volume control anyway), so I wouldn't have to really figure it out myself, just configure it according to the manuals, sorry if that wasn't clear.

HAMP568, my reasoning was mainly trying to avoid having to pick up a 7.1 reciever when I might get away with a stereo since my system is already a good amount over budget... that and if im installing volume controls anyway the impedence matching ones wouldn't be extra work.

Now I am seeing some decent prices on 7.1 systems so I will either go with that or do 5.1 with the impedence volume controls on the second and third rooms. One related question I have is that if I am setting up a 5.1 system is there any disadvantage in connecting my good speakers to the surround channels (Most models seem to warn against connecting multiple speakers to any channel besides the front for some reason)
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post #6 of 7 Old 06-24-2011, 04:42 PM - Thread Starter
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I didn't really make it clear that I will be connecting my main speakers to the surround channels because I need to use the front terminal for the two parallel speakers, according to the product manuals.
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post #7 of 7 Old 06-24-2011, 06:24 PM
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You'd probably be better off looking for a good deal on a used 7.1 unit...

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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