3 wires for 2 speakers on new RX-V750

[jlara]

I am updating my Parent's Home Theater. They had a very dated system from 1992.

I noticed the wire labeled as rear (two in wall mounted speakers) only had three wires. Two positive and one negative... I am somewhat familiar because of car systems with different ways to wire speakers to drop the ohms. I do not remember what this setup is? Is it bridged or in series? Does it matter?

I am hooking everything up to a new Yamaha RXV750 with a Yamaha DVDC750 DVD Changer.

 

[Audioholics]

You should test at low output levels but I would guess that the "negative" wire is common to both speakers. Weird and somewhat lazy setup.

 

[jlara]

I agree, it does seem to be a very lazy setup... Do I need to loop the negative at the back of the receiver, or will it work with just the negative in one of the outputs?

 

[Dumar]

Can you gain access to the speakers so you can ring out the cables? ... just to make sure you know what you're dealing with.

As far as the negative terminals go, I would be inclined to gang them together. Anyone else have thoughts on this?

 

[jlara]

Not really, the rear surround speakers were mounted when the house was built... I really do not want to disturb them. I am curious what the YPAO will say when everything is hooked up? I am waiting for one more component, and I might hook it all up this weekend.

 

[MacManNM]

Solution

You will need to get an ohm meter, and ring out the cables . The neg should be common to both speakers. So you should read 8 ohms between the neg and each of the other wires. You can also take a D cell battery and make contact with the + & - while someone looks at the woofer on the speakers. When you connect the batt, the woofer should go in or out, make sure they both move the same direction when the voltage is supplied. this will ensure the phase is correct. Also whatever receiver you use, make sure the surrounds can handle having the ground tied together. You can check this with an Ohm meter and make sure the power on the receiver is off. Check the resistance between the - rear speaker terminals on the amp. If it reads 0 0hms you are ok to use the 3 wire setup. If not, you will need to re-wire it.

 

[jlara]

Quick Update:
I hooked everything up yesterday. It seems that quite a few of the old speakers are blown. The center channel is fine, but the bookshelf front right and lefts have atleast one of them blown. It shut off during the auto-config.

Zone 2 was a little difficult to setup with the remote, but I did start getting the hang of it. I was able to successfully get the surround sound working in the TV room, and get the tuner to play outside. Zone 2 is hooked up to a Niles 4 speaker selector. I had a hard time getting any volume out without it shutting down the amp. (RXV750) I took the protectiong off the speaker switch and everything seemed better. Now I know for sure I have several blown speakers outside... But that is going to have to wait.

The three wire deal seemed to work fine for the surrounds, but I have to replace the fronts before I get the feedback from the auto-config.