I am looking to purchase a VP150 center which has an impedence of 6 ohms. My receiver, however, has 8 ohms listed as the impedence. My first question is whether a 6ohm speaker will work properly with an 8 ohm receiver, and second, what is impedence to begin with?

Thanks for any help you can provide.

I can't give you a scientific definition of impedance, but all I know is it is the rating of how many ohms, on average, the speaker is taking in. A VP150 will work on an 8ohm amp as long as the amp specifies it can play 6ohm speakers. You should read your amp instruction manual, or contact the manufacturer to be sure.

Hi,
Here's the scientific explanation of impedance as it relates to speakers. The speaker's impedance is the total resistance, measured in ohms, to the flow of alternating electrical current from the amplifier. Much of that resistance is in the windings of the voice coils in the speaker drivers, but an impedance rating also takes into account any reactive elements in the crossover.

The cables between your speakers and receiver/amp also offer some resistance to the AC audio signal, but it's insignificant (usually about 0.3 ohm or less as long as you use #12 or #14-gauge wire) compared to the speaker voice coils, which typically have a 100 feet or more of narrow-gauge wire in the voice coils.

A speaker's "nominal rated impedance" isn't fixed; it varies with frequency, but the VP150's rating of "6 ohms" means that the VP150 stays above 6 ohms over much of its range, perhaps only touching 6 ohms (or a bit lower) at one frequency. Check the receiver's rear panel to see if there is a switch for "4-ohm" or "8-ohm" speakers and set it according to the receiver owner's manual.

Regards,

My receiver doesn't seem to have any feature that allows me to change the impedance. How is it that the impedance of the speaker relates to the impedance of the amp? Also, if the amp is fixed at 8 ohms, will a 6 ohm speaker not work properly?

Hi,
The solid-state amp's impedance is not fixed at 8 ohms or 4 ohms. Think of the amp's internal impedance as essentially 0 ohms (it's typically well under 1 ohm). It's the speaker that determines the impedance (it's an electro-magnetic motor that the amp has to supply power to).

But many modern A/V receivers do not have robust power supplies and heavy-duty heat sinks (for cooling), which would be too costly to include on a modestly-priced 5-channel receiver. Instead, these receivers have switches to optimize the power transfer to 8-ohm or 4-ohm speakers. If your amp lacks those switches and the owner's manual suggests that you not run 4-ohm speakers, then you likely shoudn't because it may trigger the protection circuitry.

However, your 6-ohm speaker is close enough to 8 ohms that the amp will work properly, so don't worry about it.

Regards,

Thanks Alan!

I actually just checked with H/K, and they said my receiver will work with most 4-8 ohm speakers, so I'm set!

Eric