Axiom Home Page Forums General Discussion Technical Questions 4 ohm Speakers on a 8ohm Receiver

Hello All.
I am about to venture into AXIOM territory and had a few questions. I am getting a new receiver, the HK DPR2005 which is a 7.1 receiver. It delivers 120w per channel at 8ohms. My question therefore is can I connect 4ohm Axiom's to the HK receiver without worrying about damage? What is the harm? Not quite sure I understand all this ohm business....

Thanks.

You will be fine with the H/K and a 4 ohm load.I take it you are looking at the M80s.

The most common standard for speakers is "8 ohm impedence", so most amps are optimized for that standard. If you connect a higher impedence speaker or headphones, the speaker/phones will draw less current for any given volume control setting... and most receivers don't have a problem with that.

If you connect a lower impedence speaker to the receiver, it will draw relatively more current for any given volume control setting. Most high end products also have no problem with that, but a few will detect either too much current or too much heat being generated (both only happen when playing real loud) and the receiver's protection circuits will kick in and shut it down.

There are some funny legal reasons (some UL regulation) which prevents manufacturers from specifying 4 ohm behaviour even if they support it just fine, so you have to rely a bit on word of mouth and anecdotal evidence.

Denon, HK and NAD products all seem to be fine (any model). Most of the high end products from other vendors also seem to be fine but unless we know of someone successfully running them with 4 ohm speakers we tend to stay away to avoid the hassle.

You can see where this is going... nearly everyone on the board buys one of the same three brands and we aren't learning anything new. You will probably want to do the same

You should be fine with HK. Is that one of the Digital AVR's? I would assume it would be fine, just like the other HK models?

Randy

That is HK's biggest and baddest Digital Path Receiver

Many, many moons ago I had a 40 watt/channel Technics receiver and I didn't know what I was doing really. I had some unknown bookshelf speakers. All I knew was that I wanted big sound. I happened to go to a local electronics store and found and purchased this monstrous pair of Ultralinear floorstanders. They turned out to be 4 ohm speakers. That 80 watt Technics gave these pups all they wanted and more.

Considering this, I have always been skeptical when it comes to claims that a receiver can handle a 4 ohm load vs those that can't. I'm not saying that Nad, HK and Denon aren't superior in this respect to the likes of Sony, Yamaha and Pioneer. I suspect that maybe vintage receivers drove any speaker you could through at them and there may have been a few too many cut corners over the years among all manufacturers. They all seem to have issues.

In reply to:

---

I suspect that maybe vintage receivers drove any speaker you could through at them and there may have been a few too many cut corners over the years among all manufacturers.

---

I have had the same thoughts.

bridgman: I have wondered how some of these vendors have gotten away with "false" advertising? The following describes truth in advertising here in the U.S.

|"What truth-in-advertising rules apply to advertisers? |
|Under the <http://www.law.cornell.edu:80/uscode/15/41.html>Federal Trade |
|Commission Act: * Advertising must be truthful and non-deceptive; |
* Advertisers must have evidence to back up their claims; and |
* Advertisements cannot be unfair." |
|http://www.lawpublish.com/ftc-adfaq.html |

Yes Wid, you can make a link. LOL!!

This brings up yet another dumb question that has my mind wondering. What happens whenever you run say, 80s as mains along with a VP150 and QS8s...mixing the 8 ohm speakers with the 4 ohm 80s on a single reciever. Not a problem?

In reply to:

---

I suspect that maybe vintage receivers drove any speaker you could through at them and there may have been a few too many cut corners over the years among all manufacturers.

---

A lot of really good receivers in the Dolby Pro Logic days (PL Mk1 Mod 1) claimed to be stable down to one ohm, and with some of the loads we fed them, I tend to believe that. Weird combinations of isobaric (and esoteric!! ) home-brewed passive subwoofers (including one guy with two subs with two 4ohm drivers in parallel with the subs themselves hooked up in parallel - which is pretty much just a short as far as the amp is concerned!)... near and far field speaker combinations (tower far fields, bookshelf near fields in parallel)... various active and passive crossover systems. Most of the guys even wound their own coils!

A group of about 5 of us (a buddy and I were the youngest and had the least disposable income so we'd wait for the others to make the mistakes and we'd start building at their "last known good" designs) tried pretty much everything and the receivers just took it. A few thermal-outs here and there, but for the most part, they took it in stride.

(and for Chess and Sid - I was at Brian Reimer once when someone was demoing a new stereo amp and showed off that you could use it to arc weld thin metal together!)

Bren R.