Just found out that speaker companies use to label some models as 4 ohm so they would sell better. In reality they were 8 ohm speakers. Just read this in Klipsch area.

Now I have no trust in speaker ohm labels. Can I just take a multimeter and measure the speaker to get the real rating?


"I did at one time have a mis-matched pair of Forte's. One was factory marked 4 ohm and the other was marked 8 ohm. The funny part is that both of them had EXACTLY the same drivers and crossovers inside. On top of that they both measured exactly the same impedance at the terminals.

When I inquired about this the answer was that there was a time when 4 ohm speakers fell out of favor "marketing" wise so Klipsch simply re-branded them as 8 ohm in order to stay current with market demands. As I recall they both measured around 6 ohms (nominal) at the terminals.

If your question relates to whether you should hook them up to the 8 ohm taps or the 4 ohm taps on your amp my suggestion is to try both. You'll do no harm to the amp either way. Which ever one sounds best is the one you want to use. I've had tube amps that 8 ohm rated speakers sounded best on the 4 ohm connections and others that 4 ohm speakers sounded best on the 8 ohm taps. Go figure?First of all welcome to one of the best forums that you'll ever encounter.

"'m the one who contacted Klipsch in the link that silversport posted about impedance. I can't believe that the KG4 can be considered 8 ohm"

[img]http://www.audiokarma.org/forums/attachment.php?attachmentid=191860&d=1264613046[/img]

The multimeter only measures DC resistance. Speakers are made up of reactive components (capacitors, inductors) which have impedances that vary with frequency. In addition the driver itself is an electromechnical device who's impedance varies with frequency and can actually create voltage, called back EMF, as it moves. If you want to experiment and have an old speaker driver sitting around, put you multimeter on AC volts, connect the probes to the speaker terminals and move the drive cone with your hand. You can generate a few tenth of a volt easily. (Warning: Don't use a speaker you care about in case you poke a hole through the cone.)

So, in order to figure out what the "impedance" of your speakers is you need a plot of impedance vs. frequency. These are sometimes challenging to find.

You are correct not to trust the Ohm label. At best its a measurement at one frequency or perhaps an average across a range of frequencies.

Note: Resistance is really only a valid term at DC. Impedance is the correct term for measurements that include reactive components. Both are measured in Ohms. Impedances also include a phase angle, but let's not go there in this post.

EEman, thanks for the good information.

I did find a plot for the KG4.

Even with the plot the impedance seems to be open to debate. Klipsch said it would be considered a 8 ohm speaker in USA but in Europe they want the listing to be the lowest it ever goes at any frequency. It did hit the 4 ohm line once at around 1k frequency but was 8 or higher past that.

The bottom line to me is can an amplifier handle it. Good luck getting that information.

Outlaw was nice enough to look at that chart on the KG4 and to them it would be a USA 6 ohm so still to low to run four of them off the 2150 amplifier.

The solution seems to be buying a impedance matching speaker selector.

ie. http://www.amazon.com/Speaker-Selector-Impedance-Matching-Output/dp/B002I9XKTE/ref=cm_wl_huc_item

So based on what we've learned so far do you really think there is anything that is truly a 8-ohm speaker?

Actually the statement by Outlaw is a bit concerning. For eaxmple, let's say you believed company K who said their speakers are 8-ohm so you attached four of them to your 2150 which burns up mid-way through your house party. Would Outlaw honor the warranty because they consider the speakers to be 6-ohm?

Honesty, I think you'd be OK running your four speakers as long as you don't crank the volume.

The impedance rating is a nominal value at a specified frequency. It changes for various frequencies and manufacturers rate the speaker according to what they determine to be best fit. If you buy quality speakers the rating is probably valid. Either way the speakers rarely drop into a condition less than 4 ohms and then only for moments.

I'd like to clarify the above post; I did speak with BobJ, and there must have been a miscommunication. Though I did view the provided graph, it was not used to determine the speaker's nominal impedance; we only rely on the ratings provided by the speaker manufacturer. As you can see from the following link, Klispch has rated these speakers at 6 ohms:

http://www.klipsch.com/kg-4/details

Rest assured EEman, for the purposes of warranty, Outlaw follows the manufacturer's provided nominal impedance. Outlaw will never determine warranty status by interpreting frequency based impedance fluctuations. We will, however, confer with our customers if we feel any failure was a result of excess heat generated within the receiver; whether or not that is due to an impedance load or an enclosed environment.

If you have any further questions, or concerns, please feel free to contact us at (866) OUTLAWS.

Let me clarify

Klipsh has rated that exact speaker three different ways.

4 ohm - mine
6 ohm
8 ohm

In all cases the speakers are the same build, same internally. If I had the 8 ohm label on mine, it just meant they were built in a different year or meant for a different market. There are people with my speaker with a 8 ohm label.

It matters not! The RR2150 is rated to handle all of the various impedances it will see from any of the speakers in that range. If Klipsch has actually rated that speaker at different impedance levels either they are not identical internally or the ratings are done differently.

Yes people have called Klipsh and the speakers are the same, the ratings changed due to marketing and also some countries they export to required a different label.

I was not due to physical changes.

And yes it does make a difference when you hook up 4 speakers at once and play all 4 at the same time.

Thousands of people use these speakers every day with no ill effects to their systems. The 2150 can handle the connection as long as you don't overdo the volume. If it is a really big concern get an outboard amp which can handle the load. Generally speaking though the Klipsch speakers are very efficient with ratings between 96 and 102db at 1 watt. You would really have to crank the system to ear damaging levels to challenge the 2150. You should be able to get it to around 114db spl with 65 watts per speaker. At 4 ohms the 2150 is rated at 160 WPC which means the power supply is able to provide 320 watts of continuous power which translates to a certain amount of heat which has to be removed.