Ohms Impedance?

Hi, apologies for such a basic question, but what sort of problems would I get using Sony speakers rated @ 6 ohms with a Sherwood A\V receiver which seems to recommend speakers of 8ohms or greater.
Cheers
Rich

 

None. Go ahead and use them

The only effect is that the amplifier may be able to output more power, so you might damage the amp itself or the speakers if you push it ultra hard, but it is VERY unlikely with a small change like 6 Ohm rather than 8 Ohm.

 

Tenson, thanks for the prompt response, I'm now of to fleabay to see if i can get the speakers.
Rich

 

Still, it's best to use caution. I destroyed a pair of channels in my rotel RB956 running them in bridged mode with a 6Ohm centre speaker. Speaker survived, but the amp didn't.

Granted, newer amps will have better protection circuitry, but, I still like to think they give these recommendations for a reason

 

6 ohms is only an approximation as the impedance will vary, sometimes a great deal, over the frequency range, so the 6 ohm figure is a nominal reading. The number quoted for the receiver is in order to define the power rating, i.e the power output will be quoted at a given load impedance for comparison purposes. More important for the power amplifier is its' ability to drive the speakers when the speaker impedance is low, in other words how well the amp can supply current. If the amp can't supply sufficient current you will hear distortion. Read the info from the amp it may state that it shouldn't be used with difficult speaker loads.

In your case however you shouldn't get any problems using 6ohm speakers. What is the power rating of the amp?

Kev

 

You'll note that the recommended minimum impedance of the speaker is doubled for bridged mode on an amplifier. This is because bridging involves using two channels to drive a speaker differentially, and the result of this is that each channel only "sees" half of the load effectively. Thus if you bridge an 8 ohm speaker, each channel behaves as if driving a 4 ohm load. In your case, each channel saw a 3 ohm load.

As Kev said, the stated impedance is "nominal". B&W are famous for their "nominal 8 ohm" speakers having a 3 ohm dip in the bass region. On most speakers you will see the impedance trace dipping in the bass region to much lower than the nominal value, and peaking much higher (a typical 8 ohm speaker can be 3 ohms and over 30 ohms at different points in the frequency range).

As to the original question, what sort of problems might you get? Maybe nothing. Maybe the amp will run rather hot and consequently damage capacitors or even output devices, or it may simply be incapable of supplying the required current and either shut down or blow up, depending on the protection circuitry (protection is very hard to implement well).

 

Thanks for the help guys. The amps a Sherwood RD6106R with 60W power output, sound quality is only fair at best so probably wont shed any tears if I cook it.

Rich