Another Impedance Question: receivers with built-in speaker selector

[Mahan Safaei]

I have been trying to figure this out reading the different threads but haven't had much luck:

I have an Onkyo TX-860 receiver which has a minimum 4 Ohm impedance.
Now this amp allows for 2 sets of speakers to be connected to it and has a selector, Speakers A and Speakers B.
The question is, if I connect a 4 Ohm set to Speaker A outputs, and an 8 Ohm set to speaker B outputs, and have both switches enabled on the receiver when listening to music, will I be exceeding the receiver's suggested impedance?

What's confusing is that I don't know if the A and B speakers are paralleled into the same amp inside the receiver, or in series, or if they use separate amps altogether?

Thank you in advance!
-Mahan

 

[Mahan Safaei]

I just found the answer looking at the manual.

for anyone interested, it seems like having both speakers enabled connects them in parallel, meaning the 4 Ohm min becomes 8 Ohms minimum when both speakers are enabled. See below:



Thanks,
Mahan

 

[rcs16]

That’s correct, two 8 ohm in parallel is 4 ohm which is the stated minimum. Depending on the volume level you can run a bit less but at full power going below 4 ohm could damage the amp

 

[gadget73]

4 ohm in parallel with 8 ohm is 2.6 ohm. If they go in series it becomes 12 ohms though. Some things do parallel the outputs, some series them. I had a Kenwood that went in series, if you hit A and B it would do nothing unless two sets of speakers were actually connected. Found it on the side of the road "broken", figured out the speaker thing and used it for years.