kinda off topic -- how to wire 4 speakers stereo

hey all, figured you were nice and knowledgeable enough before when helping me decide on axioms that i would ask a totally non-axiom stereo question.

my father wants to place speakers in his house on seperate floors to give some ambient music to the place. Most likely 2 for each floor for a total of 4 speakers with each floor having its own left/right combo if that makes sense. I know of receivers with multizone capabilities but i'm thinking there may be better ways of going through this then getting a 4-500 reciever with 6.1 etc when he will only use the stereo setting. so, let me hear it. Whats the cheapest/easiest way to get this done. He's not looking for the best sound quality and will probably even use in wall speakers, so i just need advice on what receiver/amp etc i need for the job.

Thanks,
Adrian

What he needs is an impedance regulating speaker switch. Radio Shack carries them: here's one.

What you do is connect the switch box to the receiver using a pair of speaker wires, then wire each pair of speakers to a different terminal on the back of the switch. The receiver will only see the load of one pair of speakers, even if you're driving four or more at once.

Slight thread hijack....an impedance regulating speaker switch? That's something I've never heard of before. If you select more than one pair of speakers, your receiver only sees one pair? How does it work? If they're wired in parallel, the impedance lowers, right? And if they're wired in series, the impedance increases, right? So does it drive multiple pairs of speakers but have the load of one pair? I have an embarrassingly basic knowledge of electronics, but I would love a dumbed down explanation of how this things works.

Adrian, if your use of "ambient music" implies that your father wants to have both sets of speakers operating simultaneously to create an effect throughout the house, then no switching would be necessary. He could simply connect two sets of 8 ohm speakers in parallel to the outputs of a stereo receiver and have both sets playing. If he wants to run one set separately from the other, then a switch such as Peter described could be used, or possibly even better get a stereo receiver such as the HK3380(little over $200) which has output terminals and on/off switches for two sets of speakers.

I'm guessing the switch would have to know the impedance of the speakers it is connected to. When it's feeding both in parallel you're right without adding anything two 8ohm speakers would be seen as 4. But the switch could add an inline 4ohm resistor before the paralleling to bring the total back up to 8. I guess this is not a vary good solution cause of the losses. But off the top of my head I can't think of a non-active solution that inccurs no losses.

thanks for the info guys. If i wire up 4 8ohm speakers, 2 each channel, the reciever will now see a 4 ohm load correct? So i just need a reciever that wont be overloaded with 4ohm speakers and im fine right?

Adrian

JohnK -

Could he not use the "B" speaker posts on his receiver? That seems like the easiest answer to this problem. If his receiver has "A" and "B" posts, that is.

Mark

I read this differently -- your father is looking to run 4 pairs of speakers at the same time -- 2 pairs on each floor. If so, another option would be to wire them in series-parallel. You can wire 4 8-ohm speakers in series-parallel and get a resulting impedence of... 8 ohms. Pretty much any stereo receiver or amp would work fine.

Can someone else draw the diagram this time ?

Mark, yes, that's why I suggested a stereo receiver(his father may have none now)such as the HK3380, which has separate output terminals(and on/off switches)to drive two sets of speakers in parallel. Since a total of four speakers was mentioned, I interpreted this to mean two on each floor.

Adrian, yes, if the 8ohm speakers are connected in parallel the resulting net nominal impedance is 4ohms. Many receivers, including the HKs, would have no problem with this.

But... aren't the A and B terminals just wired in parallel internally ? Don't you end up with a 2 ohm load if you are running 4 ohms on A and B at the same time ?

Sure, John, but 8 ohms to 4 ohms were discussed.

Agreed... but I'm seeing two different discussions here -- one talking about 4 pairs of speakers and another talking about 2 pairs of speakers. Two pairs is no problem using the A and B ports, but four pairs is a problem unless series resistors are added (but this idea seemed to be rejected because of losses).

Do you think we are talking about 2 pairs or 4 pairs as the requirement ?

Hi,

To further complicate matters, some receiver manufacturers (JVC for one) used to wire the "A" and "B" speaker outputs in series--if you wanted A and B running at the same time--to prevent consumers from lowering the impedance to the point the receiver would overheat or shut down. You can't assume A and B speaker selectors are wired in parallel.

If all he wants is okay background music, the series connection will work fine. It's just that with series connection, the impedance curve of one speaker may affect the frequency response of the other, and vice versa. They'll interact with each other with unpredictable sonic results.

Regards,

thanks for the help guys. I think i got a handle on this now.

Adrian

>>To further complicate matters, some receiver manufacturers (JVC for one) used to wire the "A" and "B" speaker outputs in series--if you wanted A and B running at the same time--to prevent consumers from lowering the impedance to the point the receiver would overheat or shut down. You can't assume A and B speaker selectors are wired in parallel.

Cool !!

>>If all he wants is okay background music, the series connection will work fine. It's just that with series connection, the impedance curve of one speaker may affect the frequency response of the other, and vice versa. They'll interact with each other with unpredictable sonic results.

Not cool !!

Thanks, Alan -- I learn something new every day !!

Professional house audio systems are usually connected one of two ways.

1. A distribution amplifier provides a seperate amp channel for each speaker. A volume control in each room adjusts the level of 1 pair of speakers.

2. 2 amp channels with sufficient power are connected to impedence matching volume controls in each room. This insures that the receiver/amp sees an 8 ohm load with multiple (2, 4, or 8) pairs of speakers connected. The power is "divided" among the rooms so a 100 Watt/channel stereo amp could deliver 25 watts to 4 pairs of speakers.

3. This non-standard option might work if you are only using 2 or 3 pairs of speakers (4 or 6 total). Get a multichannel HT receiver. Set it in 7 channel stereo mode. Connect 1 speaker to each amp channel. Add volume standard volume controls if necessary.