ohm selection

[tractng]

Guys,
What ohm do I choose?

HSU hb-1 (bookshelf)
Impedance 6 ohms nominal; minimum 4 ohms
HSU hc-1 (center speakers)
Impedance 12 ohms nominal; minimum 8 ohms

In the manuals of my onkyo sr805, it reads:

4ohms: Select if the impedance of any speakers is 4 ohms or more but less than 6.


6 ohms: Select if the impedance of all speakres are between 6 and 16 ohms

My guess is to choose 4 ohms cause the bookself met the criteria ANY. Am I correct?

I am confused.

Tony

[ddunn49]

I'm with you Tony. I have the same question. My receiver also has two settings, 6 & 8 ohms.

[ilonggo]

I have the ultimate package speakers and onkyo 905 receiver. I set mine to 6 ohm.

[spyboy]

Guys,
What ohm do I choose?

HSU hb-1 (bookshelf)
Impedance 6 ohms nominal; minimum 4 ohms
HSU hc-1 (center speakers)
Impedance 12 ohms nominal; minimum 8 ohms

In the manuals of my onkyo sr805, it reads:

4ohms: Select if the impedance of any speakers is 4 ohms or more but less than 6.


6 ohms: Select if the impedance of all speakres are between 6 and 16 ohms

My guess is to choose 4 ohms cause the bookself met the criteria ANY. Am I correct?

I am confused.

Tony

One of my recievers has an impedance switch. When I read the test results, I found out that selecting the lower impedance (on my receiver), severly limits the amount of power the receiver can deliver. This is done deliberately to prevent overheating of the receiver.

From what I have read, Onkyo receivers (of late) have been very sensitive to overheating issues. The receiver that I have is made by Nakamichi, and I never had any problems of any kind running 5 ohm speakers with the impedance switch set to 8 ohms. I wanted as much power as I could get.

Since you are almost certainly going to use an 80Hz crossover to your mains, center, surround speakers and a powered subwoofer (to handle the power hungry frequencies below 80 Hz), the diminished power output you will have available to your speakers in the 4 ohm setting should be more than adequate. Your receiver will have to deliver about 67% less power using the 80Hz crossover, so even if you lose 45 watts per channel you should be just fine.

Very few speakers are rated at 8 ohms, and even the ones that are rated at 8 ohms dip below 8 ohms at certain frequencies.

Never the less, if it was me, I would try using the 6 ohm setting and see if the Onkyo 805 gets really hot. If not, I would be comfortable using the 6 ohm setting.

The problem is that most receivers cannot deliver the extra current into lower impedance loads without overheating, or at least running very hot to the touch.

You amost certainly will not harm your Onkyo 805 if you try the 6 ohm setting carefully, (checking for overheating). You may wish to use the 4 ohm setting if you are going to worry about damaging you Onkyo 805.

Another considertion is how loudly you are going to be playing your system. As you approach Reference Level, it becomes important to use the lower impedance setting.

Yet another consideration is whether you are running a 7.1 system or a 5.1 system. If you are only driving 5 speakers and a powered subwoofer you will not be placing as many demands on the Onkyo's amps.

The efficiency of your speakers, the size of your listening room, and the length of your listening sessions all play a part in the safety of running your receiver in the 6 ohm mode.

Finally, I don't know why receiver makers even mention 16 ohm speakers in their owners manuals, I haven't seen a 16 ohm speaker for about 35 years.