Anyone running their Kenwood receiver at 6 ohms?

MichaelDDD · 10-07-2003, 11:42 PM

Hello,

I have a Kenwood VR-409 receiver. It's rated for 8-ohm speakers.

I want to run an Axiom VP-150 center channel on it. The VP-150 is rated at 6 ohms.

I was thinking being that all the other speakers I'll be running are rated at 8 ohms, the receiver wouldn't mind one speaker being only 6 ohms. Call it rationalization.

I emailed Kenwood and asked if I could get away with this. I told them all the other speakers would be 8 ohms. Here's what they said.

Quote:

Thank you for writing to us at Kenwood USA Corporation.

In regards to your inquiry, the VR-409 is rated at 8 ohms. We do not recommend connecting 6 ohm speakers to the receiver. Doing so could damage the receiver.

I know it COULD damage the receiver...but will it?

MichaelDDD · 10-08-2003, 09:15 AM

The collective mindset of this Encyclopedia of Electronic Knowledge is stumped?

Aaron Gilbert · 10-08-2003, 12:06 PM

Michael,

Don't worry about the lack of response. I think hardly anyone uses Kenwood receivers on these or other forums (such as AVS). I asked the same question about a Kenwood VR-5090 and got no reply. I also had written to Kenwood and received the same exact generic response you did - just substitute 6 ohms in place of your 8 ohms.

The best advice I can give is to try it out with your receiver. I personally suspect that it will be just fine. It's my opinion that any decent receiver should handle even four ohm loads without issue, so long as you are offloading all the bass to a powered subwoofer. Any receiver these days has at least short circuit and thermal overload protection, which will shut the unit down if it encounters a problem.

For what it's worth, I have a Kenwood KA-128 from the late 80's. It too is rated with only 8-16 ohm speakers. It's not a giant either, weighing less than 30 pounds. It drives 4 ohm speakers with ease (and my particular speakers have been measured as low as 2.5 ohms at certain frequencies).

I've only encountered one receiver so far that has actually had a problem running 4 ohm speakers at normal volumes, a early 90's 40w/ch Technics receiver.

I don't buy Kenwood's idea that you will damage the receiver, that's just legalese.

Aaron Gilbert

Paul Chalk · 10-08-2003, 12:28 PM

Be careful with the VR-409. I used to use one. I was using it to power my B&W 602's about a year ago. I was listening at a moderate volume, about -30dB, and it blew one of my tweeters. The receiver still works fine. But keep in mind, if the Kenwood clips, it's the speaker that usually suffers the most.

Because the VP150 is very efficient, 95 dB, the 6 ohm impedance might not be a problem. Nevertheless, you should still use caution until you upgrade your amp.

John Garcia · 10-08-2003, 12:32 PM

A single 6 Ohm speaker will probably not cause any problems specifically, BUT, if the receiver has limiting circuitry, you may have the receiver shut off under dynamic loads with a lower impedance speaker.

The 150 could potentially draw enough current to clip at high volumes, and that would be bad for the speaker not the receiver.

Heat is another byproduct of driving the amp harder, and can definitely be your enemy if the amp section is not up to the task.

My receiver is rated for 6 Ohm speakers and I am running 4 Ohm mains.

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Aaron Gilbert · 10-08-2003, 12:44 PM

Paul raises a good point, about the efficiency. A speaker rated at 95 dB 1w/1m (or 2.83v/1m) will draw a good deal less current than your average speaker, which I believe is probably still around 89 or 90 dB.

Let's look at an example using an arbitrary 100w level. A speaker rated at 89 dB for 1w/1m will draw:

8 ohms - 3.53 Amps
6 ohms - 4.08 Amps

Now for the same sound pressure level, a speaker rated at 95 dB for 1w/1m will draw:

8 ohms - 1.77 Amps
6 ohms - 2.04 Amps

You can see, that the more efficient 6 ohm speaker will be a much easier load for the receiver, in this case. It's all about current supply when you are using lower impedance speakers. Don't exceed the capabilities of the receiver's power supply and output stage, and you should be fine.

Of course, there are other factors which come into play, such as the complexity of the load, ie the reactive (capacitative/inductive) components of the impedance. But so long as those aren't wild on your 6 ohm speaker (and most are not), you should be fine.

Aaron Gilbert

Doug_H · 10-08-2003, 12:46 PM

I have run a number of Kenwoods with 6ohm speakers. the 309 and 409 will clip at relatively low levels causing speaker damage. they seem to do the same at an 8 ohm load though.

The 5090/5700/5900 do not have this problem and are solid receivers and a very different beast from the department store models.. I am currently running a 5900 and have no clipping problems at all.

Aaron Gilbert · 10-08-2003, 01:14 PM

Doug,

Thanks for the feedback on the Sovereign receivers. I had a feeling they ought to be significantly more beefy than Kenwood's regular line. As fate would have it, my VR-5090 won't be powering any speakers, after all. I picked up a KM-X1000 off Ebay last week for the front L/R, have another of the same bridged for my subwoofer, and a Legacy/Proton LUM-A1 will be serving the other five channels. I wonder if I have enough power, let's see.. 1400 watts for my 2700 ft^3 room. And my speakers are about 94 dB at one watt except for the sub which is only 89 dB.

Aaron Gilbert

Doug_H · 10-08-2003, 01:17 PM

Aaron

I will be listening for your system here in Texas