impedence matching on 4 sets of speakers

[kpierce]

I think I understand impedence matching volume controls as the ability to control the volume on multiple sets of speakers.

However I have a little different situation (I think). I have a central location in my family room where all the audio wiring is run to. From this spot each of the 4 rooms has a CAT5 and large speaker wire which contains 4 wires. This all runs into a junction box in each of the 4 locations. Coming into this box is two sets of speaker wires. So at the junction box, I assume this is here for volume control's to be installed.

I have a receiver with an A/B set of speakers. Can I pump half of the rooms (2 of them and a total of 4 speakers) on A and the other 2 rooms and 4 speakers on B?

I am thinking then I would just use a volume control to turn them off in one of the two locations if it is not needed.

For example: Game Room and Office would each be hooked to Speaker A in the back of the receiver and each room would have it's own volume control. So if I turned the receiver on and only wanted music in the Game Room I could turn the volume knob in the Office to 'Off'.

Would this work? Would I need to be looking at some type of special volume control other than one with an ON-OFF setting?

thanks

 

[korgoth]

which receiver do you have? and im not sure what you mean by impedence matching.
impedence is the ohm rating of your speakers... most newer speakers are 8 ohm, but some are 6 and 4.

you dont need to match impedences, but if you have 4 ohm speakers, you usually need to run a seperate amp.

the mutli room stuff youre talkin about probobly needs a seperate amp to run 4 different rooms.
were you talking about running the same thing to every room? or did you want music in one room and a movie playing in the other?

each room will not have its own vilume control on the receiver. im not sure if you meant you had a seperate volume control set up already, or if you wanted the receiver to do that. You can have 2 volume controls on the receiver, if you have a multiroom feature. the a/b is just on and off.

 

[jcPanny]

Receiver connections

Most receivers are not capable of driving 4 ohm loads (2 pairs of speakers connected to the speaker A terminals). Similarly, most receivers share an amp for the speaker A/B terminals so they can not drive speaker A AND B at the same time. For example, if you had 4 pairs of 8 ohm speakers connected as you described, running A AND B, your receiver would be seeing a 2 ohm load and it would probably go into shutdown after a few seconds.

First, give us the specs on your current receiver so we can determine if it has enough power to drive 4 pairs of speaker at once (w/ impedence matching circuitry). If it is at least 100 Watts per channel, then you are probably OK and here are a few options.

1. Keep is Simple:
Connect the speaker wires to your receiver as you described. In each room connect the input and output speaker wires to an impedence matching volume control with the jumper set for 4 pairs of speakers ($25-50 each). Use the receiver's volume knob to set the max volume and the controls or A/B switches to turn each room on or off. If your receiver doesn't have enough power, you may have to add a $100 audio source amp to this setup.

2. Complicated:
Connect a distribution amplifier to the line output on your receiver ($2-500). Connect the cat 5 (and possible speaker wire) to the distribution amp. Connect the cat 5 to keypads in each room ($100 each). Some of these systems will allow you to listen to a different source in each room, use IR remote, etc.

 

[kpierce]

The receiver I have is an OLD one. Pioneer RX-721. The specs state: Continuous Average Power Output is 125 watts per channel, min. 8 ohms from 20 Hertz to 20,000 Hertz with no more than 0.09% total harmonic distortion.

Would this drive 8 speakers? 4 hooked to A and 4 hooked to B? These would not all be running at the same time, 4 speakers total at anyone time.

I would be turning them off at a volume control in each location when they were not in use.

I still don't understand the impedence matching thing.

In my mind right now I would be doing the following:

Splicing speaker wire to connect 4 speakers into the two connections on A and the same on B. Hooking 4 sets of speakers in each room. Connecting them to the junction box in the room which is connected to a volume control. Use the volume control to turn music on in the rooms I want to hear it in and off in others.

If this will work, will there be some special type of volume control I would need?

Will I need to make sure the speakers have a certain ohm rating? 8 perhaps?

Sorry to be so thick and slow on this subject, but I 'almost' understand!


I hope this makes sense.
thanks

 

[korgoth]

plugging 4 speakers into 2 connections will probobly work, but they would need to be 8 ohm speakers. putting 2 speakers into one input would create a 4 ohm load onto your receiver. dont turn it up too loud.

4 ohms isnt good, but if you keep it at reasonable levels, it might be ok. It definately wont power all 8 speakers at once. i think that would be a 2 ohm load. and you would easily blow your receiver.

You can run the speakers in series if you are worried about ohm load, and it would lower the impedence back down to 8.. but the speaker volume would be lower, and youd have to run mono to each room. you could try this since it seems like you dont care to much about surround sound. You can run your speakers safely this way. just hook a pair of speakers up like this.. run the negative of one speaker into the positive of the other speaker, then run the positive and negative thats are still open into the receiver.

if the volumes are too low or you end up shutting down your receiver, then youll need to buy another amp.

 

[kpierce]

Thanks for the info. So hooking up the speakers as mono as you have described would lessen the load or something? I think I understand what you are saying, just curious as to why this would work...