HK and 4 Ohm speakers.


I was wondering if anyone knows why HK does not specify 4 Ohm compatibility with their receivers? I have emailed them about the 525 and they told me that this receiver should not have any problems at all running 4 Ohm speakers. So why would the company not put that in the spec sheet of the product? I think it would help the company image even more and get rid of some of the confusion surrounding their products comptibility with 4 Ohm speakers.


Not all 4 ohm speakers are the same. Some are a minimum of 4 ohms and some are an average of 4 ohms (getting down close to 3 ohms at some frequencies). You see, speakers are not a consistant impedence, but in fact the impedence varies by the frequency. As an illustration, I have included a link for the impedence curve of the Ascend Acoustics CBM-170 speaker:

You will note the spikes at 36 and 88 hz which exceed 20 ohms. You will also note the dip to 4 ohms at 200 hz. This is typical! In fact, I would argue the Ascend has one of the better impedence curves I have seen. Even though rated at 8 ohms (nominal), the range is anywhere from 4 ohms to 22 ohms. Usually, I see a wider range of impedences than this one.

Well, some 4 ohms speakers are more consistantly low and the H/K would throw up if it had to drive them (e.g., Magnepans). Some other 4 ohm speakers are a little more forgiving as their rated at 4 ohms, but are more of a 4 ohm minimum, which the H/Ks should be able to drive (e.g., PSB). Their tech department is talking about the latter type of 4 ohm speaker, but the fact remains that the design department didn't design the product to drive 4 ohm speakers, especially across five or more channels. The reason is cost.

Another person on this forum (Paul T., I think) actually contacted the tech department at Polk about a proper amp to drive his Polk LSi speakers, rated at 4 ohms. H/K was not on their list of acceptable amps. Since Polk recommended 4 other brands, I have to conclude they tested the receivers and found the H/K was simply not designed to drive their 4 ohm speakers and its performance was unacceptable.

Receiver design is all about trade-offs, especially as the price goes down. Ususally, a 4 ohm load is indicative of an audiophile class of speaker, meant to be driven by high end electronics, not a mass market receiver. Receiver makers know this and almost all of them have written off driving 4 ohm speakers as it would cost too much extra to make the receiver tolerate them (usually means much higher quality power supply and capacitors, at the very least). You see, you want a particular function and the mass market receiver makers are looking at making a price point. For those who want to drive 4 ohm speakers, you usually have to go to NAD or separates because that market is too small for the big mass market companies to worry about.

I am not telling you what should be, but simply what is. I hope I have answered your question.


You definately answered the question, thanks.

I still think they should put at least something in writing...or some kind of disclaimer. I was looking at other receivers including the NAD but the problem is that I find the NADs a tad too expensive for what you get in terms of features and I have always loved the sound quality of the H/Ks. I don't want to sound like I am knocking NAD at all. I am sure they are awesome receivers which produce amazing sound. It's just a personal preference.

Thanks again Hawk for taking the time to answer my question.
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