Axiom Home Page Forums General Discussion Home Theater Wiring two speakers to one binding post

Would it be physically bad for either the speakers to the receiver if I hooked up two bookshelf speakers to the center channel binding posts of my Harman Kardon AVR-120, effectively creating two center channel speakers?

Depending on the impedence (resistance) of your speakers you would (I am assuming) be hooking them up parallel and halving the total. If your speakers are 8 ohm this results in a 4 ohm load to your amp. If your amp is capable of managing a 4 ohm load, these speakers would sound louder than the rest making your system unbalanced for HT. You could also run the risk of burning out the coils in the speakers if they are unprotected and the current gets too high.

Comments anyone??

4-oHm speakers offer LESS resistance, and that is why when they rate a receiver @ 4 ohms the wattage is always higher?

Exactly. The lower the load, the higher the current. My receiver is rated 130W into 6 ohms and 105W into 8 ohms.

First, make sure both speakers share the same impedance rating (that is, make sure they have the same ohm rating)

Now, let's see if I remember my math correctly...

Connecting both speakers to your center channel binding posts places them parallel in the circuit, so you will want to take the stated ohm value and divide it by 2. Take that new figure and make sure the receiver can handle it. If so, you should be okay.

For example, two 8 ohm speakers connected to the center channel binding posts will actually have a 4 ohm load on that channel. Similarly, 6 ohm speakers will have a 3 ohm load and so on.

I'm sure someone will correct me if I am mistaken.

- David

/edit
Shucks. It looks like Sean beat me to it! :-)

The general concensus on the boards when I proposed the same thing was that it wouldn't be a problem (I originally asked about getting a speaker switch to do it--I think JohnK said that it wasn't necessary). Not that I've tried it yet, but I intend to use 2 M2s as my center channel, if I ever get around to doing multichannel.

Jordan, as other replies have indicated, if you hook the two speakers in parallel, that halves the impedance(e.g.two 8 ohm speakers in parallel present a 4 ohm load).Assuming that the amp can handle the impedance without shutting down, no problem.

Also note that impedances are averages; i.e. given different loads a speaker will change resistances.

This leads me to two comments:
1. If you do this, make sure the speakers are twins, not just nominally 8 ohms.
2. If you can, get a resistance chart for the speaker model (like the M80ti one Alan so helpfully linked to in a recent comment). If the chart shows a big dip in resistance somewhere, don't wire them this way. The severity of the dip will be twice what it normally is if you do.

Hope this makes sense- basically, I'd recommend this only on identical speakers and only if the speakers are a solid 8 ohms given any load.

A good point. Alan, care to supply the chart for the rest of the Axiom speakers?

If there's concern over wiring them in parallel, why not wire them in series? The nominal impedance would double (16 ohms)--still safe for any receiver.