Not the same old impedance question!

[c0mputer]

I've searched hard and long through the threads for an answer and haven't come up with one.

We all know the story. An 8 Ohm receiver will drive 4/6 Ohms speakers. Good, we know that, who cares.

My question is whether a 6 Ohm receiver will drive 8 Ohm speakers? I have an Onkyo receiver only capable of 4/6 Ohms. In Australia it's very common to find receivers only capable of 4/6 Ohms and not 8 (I think it's related to our 240V mains, I don't know???)

I'm after some di-pole speakers that are rated at 8 Ohms. Would running my receiver at 6 Ohms over drive the speakers? I don't want to shell out cash to find out the answer is no.

ps. The receiver is capable of delivering the correct wattage.

thanks

 

[markw]

As you noted, low impedances can be a problrm, but...

...using a higher impedance speaker is not a problem.

A low impedance puts more stress on an amp while a higher impedance lets the amp breathe a little easier.

 

[Votrax]

The recommended speaker impedance of a receiver is actually the minimum the manufacturer will specify. As markw said you can use higher impedance speakers as they'll draw less current. Of course you won't get the same power to an 8 ohm speaker as you would to a 6 ohm speaker. If your receiver will supply 100W into a 6 ohm load it will be around 75W for an 8 ohm load.

 

[Kurt C.]

We all know the story. An 8 Ohm receiver will drive 4/6 Ohms speakers. Good, we know that, who cares.

My question is whether a 6 Ohm receiver will drive 8 Ohm speakers? I have an Onkyo receiver only capable of 4/6 Ohms. In Australia it's very common to find receivers only capable of 4/6 Ohms and not 8 (I think it's related to our 240V mains, I don't know???)

You've got this backwards, which may be the source of your confusion. A receiver rated to 4 Ohms will easily drive an 8 Ohm speaker. The opposite isn't true.

A 4 Ohm speaker is more difficult for a receiver (amplifier) to handle than an 8 Ohm one.

To explain further, 4 Ohms is twice the amount of resistance as 8 Ohms. A good receiver/amplifier is capable of delivering roughtly twice as much voltage into a 4 Ohm load than to an 8 Ohm load--that is to say, if it puts out 10 volts in response to an 8 Ohm load, it will put 20 into a 4 Ohm load, 40 into a 2 Ohm load etc. A receiver that is only rated to 8 Ohms won't be able to increase the voltage supply to keep up with an increasingly difficult load.

 

[malvado78]

He does not have it backwards. He is not worried about his receiver he is worried about his speakers. He says he is worried about OVERDRIVING HIS SPEAKERS. The answer is don't worry about it they will be fine.

 

[Kurt C.]

We all know the story. An 8 Ohm receiver will drive 4/6 Ohms speakers. Good, we know that, who cares.

Are you saying the above statement is correct? An 8 Ohm receiver will drive 4 Ohm speakers? Perhaps it was a typo but this most certainly is backwards. A receiver rated to 4 Ohms will easily handle an 8 Ohm load. A receiver rated to 8 Ohms may overheat or shut down if faced with the task of driving a 4 Ohm speaker. Consult any basic audio engineering text if you need a second opinion.

 

[Kurt C.]

My question is whether a 6 Ohm receiver will drive 8 Ohm speakers?

The short answer to the real question is yes, a 6 Ohm receiver will easily drive 8 Ohm speakers and is unlikely to overdrive them. If you are worried about damaging your speakers, you should know that it is far morecommon for people to damage speakers by using an underpowered reciever (which will clip) than one that is "too powerful"

Perhaps my detour to correct what may have been a typo in the original post was unnecssary. I interpreted it as a basic misunderstanding of electrical resistance. My apologies.

 

[malvado78]

Sorry. No I wasn't. I thought you were address the question not that statement. I dismissed that statement as the question most people ask around here "will my (insert receiver here) drive these speakers" and the answer is normally not to high levels but try it and keep it to low volumes and feel the temp of the receiver periodically to make sure it is not getting hot and you should be OK. But you really need a seperate amp.

 

[AverageJoe]

To explain further, 4 Ohms is twice the amount of resistance as 8 Ohms.

Now I'm confused. I thought 0 Ohms was a short, and the higher you go, the more resistance.

 

[malvado78]

The less resistence the more current that is drawn given constant voltage. Think of it as a water hose. Keep the water pressure the same (voltage) vary the diameter (resistance) 4 ohms (less resistance) is a bigger hose allows more water (current) to flow through while 8 ohms (more resistance) allows less water to flow through.

Therefore the lower resistance requires the receiver to work hard and provide more current.

 

[j_garcia]

Impedance and resistance are not the same thing. Lower impedance means lower resistance, though the two are interactive: Impedance measures resistance at a given frequency, and as the frequency changes so does the impedance. So technically, a 4 Ohm speaker has HALF the resistance of a 8 Ohm speaker, allowing more current to flow.

 

[MacManNM]

Impedance and resistance are not the same thing. Lower impedance means lower resistance, though the two are interactive: Impedance measures resistance at a given frequency, and as the frequency changes so does the impedance. So technically, a 4 Ohm speaker has HALF the resistance of a 8 Ohm speaker, allowing more current to flow.

It has half the impedance, not the resistance.