Axiom Home Page Forums General Discussion Technical Questions Ohm rating, averages, and deceit in the industry?

I was going to post a followup to the M80-specific discussion but it felt a bit like hijacking. So!

People say that the M80's are "an easy 4 ohms" vs "a difficult 4 ohms", which would lead us to believe that their average impedance might have been rounded down to 4? (I'd say it's nicer to the consumer to round down, like Axiom did, than to round up). What's the 'actual' M80 impedance with standard testing material?

On avsforum I came across a post saying that many nominally 8 ohm speakers are closer to 4? I can see why manufacturers would like to do so, but whatever happened to truth in advertising? Are there any known tricksters in the industry?

Is this much like the receiver power output situation? Are there independent testers measuring real average impedances? It seems significant!

p.s. What brought this on was, I sold my Denon 1603 for a Yamaha RX-V1400 (and a HSU STF-2). Unfortunately the Denon left last Saturday, and the Yamaha doesn't come in until tomorrow-- I'm now having serious music withdrawl. (lesson learned, have some foresight regarding this stuff!) Anyway, with the Yamaha I'm wondering if I could drive M80s (with the load switch on 8 omhs, especially if they're a 'forgiving 4 ohm load') and have peace of mind.

Cheers,
Mike

I think the reason why people say they are an easy 4 ohm load is because they are very efficient. Imagine if you had a 4 ohm speaker with a sensitivity of 89db.

to get to a moderate volume level your really using some power there!

Raindance,

I have asked the same question, regarding appropriate receivers to use with the M80's, to both the Axiom technical line and Alan Loft (resident expert on the site for Axiom, I believe).

1) Alan only recommended the following receivers for the M80's:
Denon, Harmon Kardon, and new NAD because of their robust power supplies which will drive the 4 ohm load, despite the manufacturers warnings.
He said avoid Onkyo and Sony...they will shut down with any low impedances.
Yamaha very good with all but the 4 ohm load.
2) The Axiom techniacl department recommended Denon, Harmon Kardon and Outlaw 1050.

So I would say any of those four will be fine. I thought someone mentioned on the message board that they used the Yamaha RX-V1400 and the Axiom M80's with no problems, but as far as I can tell Axiom doesn't recommend it.

Rob

I have to correct RobR a bit here.
Axiom does not PROMOTE the use of a receiver they have not tested with the M80s and they should continue to do so. Obviously they cannot test every receiver out there with their speakers, they can only recommend the receivers they know for sure will drive the M80s, but that doesn't mean other receivers are incapable of doing so.

I own an Onkyo DS797 and it has driven 4 ohm speakers no problem.
Do not rule out receivers based solely on the suggestion of knowns from a single person. If you pose the question in forums and hear from ppl who own a combination of receiver and M80s you are interested in, then you should have your answer as to whether it will work or not.
More often you will see that the receiver companies will not quote their equipment as being able to run a heavier load so they can protect themselves from having alot of returned merchandise from over zealous customers pushing things too hard. Even some of the receivers Alan has mentioned have a listed 6 ohm max limit in their manuals, yet they still work with the 4 ohm speaker.
As long as you buy a quality unit and don't skimp on the $$ too much, you are more likely to have a unit that is capable of running the M80s.

As for the M80 impedance itself, see this graph for an idea of how much the speaker averages at the 4 ohm level.

Chesseroo,
Thanks for the reply. Guess I need to be more careful when wording replies, I don't want to get anyone in trouble.

Chesseroo is correct in saying that Axiom can not test every possible receiver on the market.
I should clarify that when I called the Axiom tech line they said the Denon, Harman Kardon and Outlaw 1050 would work with the M80 speakers. That does not mean that all other manufacturer's receivers will not work. These are just three manufacturers they have used, and are comfortable with. Also, by no means did I mean they were promoting these products...I just asked for some receivers that they knew would work.
Also I should say Alan Loft and/or his colleagues have used Denon, Harmon Kardon and the NEW NAD with the M80's, and have had satisfactory results.
So the above are four receivers Axiom and/or Alan have used, and have had good results with. This is not the only four that will work by any means, just ones that they had used and had satisfactory results. As, Chesseroo has stated he has had good luck with other manufacturers as well.

I am looking at buying a receiver and speakers myself. There are a large number of mfgr's available, and I was happy to narrow the search down to four. These are not the only four that will work, but for me I looked at it as....these are four that will work, so for me it's is a good place to start.

Rob

These are some of the speaker combinations I've used with my Yamaha RX-V2400:

Magnepan MG-12 - 4ohm, sensitivity=86(not an easy load, comparitively speaking)
Kef Q-95 center - 4ohm, sensitivity=91
Kef Q-75 mains - 6ohm, sensitivity=91
Kef Q-15 surrounds - 6ohm, sensitivity=91

The 2400 has performed flawlessly in my 15'X20'X14'(vaulted celing), well dampened room with no diminished dynamics, no clipping (at fairly high levels {as high as the pain threshold would allow}), no image smearing and the unit does not get any hotter than any other SS, receiver I've ever used. In fact, it has run considerably "cooler" than the Denon it replaced. BTW, the Denon with a power rating of 85 w/ch had no problems driving these speakers either.

Of course, your milage may vary but unless you have just a humongous, sonicly dead room, the Yamahas' should not pose any "matching" problems with most relativly effecient speakers of the 4ohm ilk. IMHO.

I also should have chosen a word better than "promote".
"Suggested" would have been more fitting i think.

Sushi was one of the first posters to put the myth of the Pioneer receivers to rest. They vehemently stated that their receivers were not for 4 ohm speakers but sushi (and others) proved them wrong.

So mwc, have you actually measured the max SPL just before distortion/clipping at a set distance with these speakers and receiver combos?
How about with the Axioms?

Could you also post some of the Yammy info ($, specs) along with a reply.
Thanks.

oh and while we're at it. i dont think alan has actually used the new NAD recievers. I just brought it up in a post that they will drive 4 ohm speakers, even says so on their website as they rate the continous power into 4 or 8 ohms.

Sorry chess, I did not take any SPL measurment regarding distortion/clipping. The level I was refering to was the one that I could comfortably listen at before my head exploded.

Oddly enough, while I have had my Axiom M22s in this system, I haven't pushed them to high volume levels and they were in the system only for a day. For the most part, the M22s have been hooked up to a vintage Sansui intergrated amp in a bedroom system.

As for the specs in the RX-V2400 was there something other than this or this
that you were asking for?