Axiom Home Page Forums General Discussion Home Theater Question about ohms

I see, fact finding mission. FWIW, my midgrade Denon 1804 had no troubles driving the M80s and parallel M22s(which is a ~4 ohm load).

Hi Seeking,

While JohnK is supremely confident of any AV receiver being able to drive Axiom's 4-ohm M80s/VP180s with ease, that is not the customer history we have here at Axiom. I will now recite, yet again, the brands of AV receivers that have never had problems of protection-circuitry shut-down or current limiting driving the M80s: Denon, Sherwood Newcastle, Harman-Kardon, Rotel, Outlaw Audio, B&K, Macintosh, and NAD. This list includes even entry-level models from Denon, H/K, Sherwood Newcastle, and Outlaw Audio, which we checked out at our factory listening room.

Note that the above list assumes the owner is not trying to drive the AV receiver beyond its output limits or into clipping. Any well-designed AV receiver will temporarily shut down if cranked to levels that trip the thermal sensors on the output devices.

Older models of Onkyo, Yamaha, and Pioneer were not stable with the M80s and would repeatedly shut down.

I'm a bit hesitant to recommend even recent Onkyo models because I note that in Dan Kumin's recent tests of an Onkyo for Sound&Vision magazine, when it was connected to 4-ohm loads, it went into current-limiting mode after about 2 seconds, which limited the power output in all channels to 45 watts per channel maximum, regardless of where the impedance switch on the receiver was set.

Regards,
Alan

That last bit about a recent Onkyo test is interesting. I came close to picking up an 807 before I found my current Denon on sale.

I am quite content with the Denon as I can push it to very loud levels without the receiver getting anything more than a little warm to the touch.

A few times when I watched a movie pretty loud (-6dB from ref), my Denon got pretty hot to the touch but never shut down. I'm very happy with it as well.

Fred, yes the Onkyo test is interesting, and I'm quite familiar with it and others there, since the S&V tests are among the very few that I study carefully. And it is indeed necessary to study them carefully, especially following what the asterisks on the power measurements refer to, if a misunderstanding is to be avoided. The test results here show that the limiting on power output by the protective devices during 5 and 7 channel operation was at 8 ohms, not 4 ohms. For 1 channel and 2 channel operation into 4 ohms(with the setting correctly left at the higher impedance)the 4 ohm outputs were 272 watts and 229 watts respectively. These are the numbers which should instill "confidence" in an owner of that unit.

Mr. Kumin, as he typically points out when he has no problem with real-world use with his lower sensitivity speakers, states that the multi-channel signals of that description "...essentially never occur "in nature" from music or movie soundtracks-only artificial test signals". These excellent results led to the highest grade of "10" being given for performance.

It's also interesting to note that earlier in the year the Denon 4810(about two steps higher up in their model lineup)was similarly tested and showed a fairly similar reduction in 7-channel output into 8 ohms, as shown here . This again led to a similar comment that it was a result "which is neither uncommon nor particularly meaningful".

Lab test results have to be studied carefully to determine their applicability to home listening. If the multi-channel power reduction into 8 ohms was taken as representing a realistic scenario in actual home use, the absurd conclusion might be that neither the Denon or Onkyo was advisable for use with speakers rated at 8 ohms or less(meaning almost all available speakers).

I know Sherwood Newcastle definitely has a hard time running 7-channels and will go into protection mode with the M80's,VP150,and QS8's.


Edit: Sry, meant to say at higher(ok..hearing harming) listening levels.

I'm trying to talk myself into getting some M80's later this year... I have a H/K (AVR630) so I think I'd be able to drive em with that (AVR upgrade will be in the future).

Talking about professions/education. I have an Associates in EET thou I confess to have probably forgotten half of what I learned since I've been in IT for the last 15 years. But electronics were always my first love. That was the only time I ever actually enjoyed school.