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

The Rotel receivers and or power amps are also solid. They powered my 4 ohm inefficent Maggies with no problems.

So what's the deal with the 2400 bass management that my 1300 doesn't do? I'm lost...as usual.

Jim, are you referring to the fact that the 1400 and 2400 have a wide choice of crossover frequencies between the speakers and sub, varying from 40Hz to 200Hz? The older Yamahas have a fixed 90Hz crossover, which is close to the most commonly suggested 80Hz. Someone using very small satellite speakers(e.g. Bose cubes)might have to use a crossover of 150Hz or higher because of their lack of bass response. Someone on the other hand using much larger speakers might(mistakenly in my view)want to set the crossover even lower than 80Hz for fear of "wasting" some of the bass that their speakers were capable of.

In reply to:

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Someone on the other hand using much larger speakers might(mistakenly in my view)want to set the crossover even lower than 80Hz for fear of "wasting" some of the bass that their speakers were capable of.

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John, you bring this up all the time but you have a "mistaken" view of people's perception. Granted some newbies have the question, "well why did i buy towers if i'm not going to use their bass drivers anyway?" and they should be given both reasons so they can decide for themselves.
Just to be clear now, there is no fear one is losing or wasting the bass of our towers. People, such as myself, may not like the overbearing sound of a sub playing notes in the higher bass area. I find it too boomy regardless of gain settings and if i lower the gain, i would have to turn it back up again for HT. Using the sub takes away the whole tightness of bass i was searching for in a speaker in the first place.

My personal reasoning for using a cross on the sub at 45Hz-50Hz and allowing my M60s to play as 'large' is to use the bass of the M60s for music while keeping the subwoofer for the truly low end musical bass notes (what the subwoofer is really designed for) and yet still having it add plenty of explosion oomph during HT.
As long as one mixes the crossover so the sound meshes together well, then it doesn't matter whether the THX suggestion of 80Hz or whether the cross is 50Hz, 40Hz, 120Hz, etc.
There is no 'mistake' in doing so.

As for the idea that Alan mentioned in regards to lessening the burden on one's amp/receiver, as long as the unit is robust enough, the difference is negligible if at all. I certainly have not heard any significant change in using the 80Hz vs. a 50Hz cross with my M60s. Certainly nothing that is so pleasing as to override the awful boom bass i also have to put up with in such a configuration.
If you try it out, it really does work nicely.

For those who have the M22s or another speaker with a far lesser bass extension or perhaps prefer a heavier low end sound than what the M60s can put out, then by all means, use the 80Hz or higher values. In this instance, the sub will provide more benefit than disadvantangeous boomyness.

Hi Raindance,

If you examine the M80's measured impedance curve (thanks to Chess for posting the link), it's quite smooth and "linear"; i.e, there are not dramatic peaks and dips in impedance. The M80s curve hovers around 4 ohms between 100 Hz and 500 Hz and is above 4 ohms over the rest of the audio range.

That is considered a relatively "easy" 4-ohm load, because it's smooth and linear, however, if a receiver does not have a robust power supply capable of supplying enough current into a 4-ohm load, then it isn't "easy" for that receiver. This is why previous Yamaha receivers have 4-ohm impedance switches that reduce the voltage drive in the 4-ohm position, thereby limiting power output and avoiding excessive current flow and heat build-up (and shut-down). By contrast, a "difficult" 4-ohm load might have fluctuations to 2 ohms or less followed by peaks in impedance.

Gene's tests of the new Yamahas on his Audioholics site are very thorough, and, as I suspected, the auto-EQ circuits are no panacea. An Axiom customer complained to us suggesting that his speaker had been wired with the polarity reversed. Not so. The Yamaha auto circuit mistakenly identified the speaker as being "out of phase" with the rest of the system, just as Gene DellaSala experienced in his tests of the Yamaha 2400.

It's true I've not used the new NAD receivers, however, a number of Axiom customers have reported that they easily drive M80s. Moreover, I checked with a very experienced engineer and amplifier designer who consults to AXiom (he has designed amplifiers, both solid state and tube, for Macintosh, Luxman, Harman/Kardon, and others, and is entirely familiar with the circuit design of the new NADs). He confimed that the NAD receivers do NOT impose current limiting (thereby reducing the power output) when set to drive a 4-ohm load.

Most other receivers that have rear-panel 4-ohm impedance selector switches do impose current limiting when set to the 4-ohm position. As to whether the new Yamahas will drive the M80s when left in the 8-ohm position, you'd have to try it at higher volume levels and see if the Yamaha's protection circuitry dectected the lower impedance and shut it down.

Regards,

That is in fact what I was referring to. Now I see why the different numbers are needed. Thank you.

Alan,

Thanks a lot for your comment. I feel that, with all the wonderfully smart people around, my audio education is in very good hands here.

As a sidenote on the Yahama RX-V1400, from my research I think a great deal of the innards have been overhauled for quality's sake compared to their earlier receivers:

To quote http://www.yamaha.com/yec/products/RECEIVER/RXV1400_lit.PDF (Basically a feature overview):

"Finest parts used throughout for high sound quality" (through deconstruction perhaps implying this was not always the case but is now)

"High Current Amplification Achieves Low Impedance/High Current Power from Input to Output" ...

"Yamaha receivers have always had fairly high current levels (ed: perhaps not), but with the RX-V1400, we have further improved this performance"

"Finest Parts Used Throughout ... Yamaha technicians completely re-evaluated all the parts used in previous receivers. As a result, many were replaced with more expensive or custom-designed units." (It goes on to detail the capacitors and transformer used)

Hopefully Yamaha is playing it straight and this is a new beast, much more capable of driving low-impedance speakers.

Best,
Mike

Well.... I tend to take marketing materials with just a little grain of salt. I mean, Bose has the best sound in the world from just a little radio, if you read their stuff. And KFC is health food.

True!

Hmm...

Perhaps the most convincing thing about the truthfulness of the yamaha RX-V series literature is that it makes the HTR series look bad (by comparisons in the literature).

Mike,
Where is there mention of the HTR series?
Doesn't sound good for me, since I was hoping to get a big discount at Best Buy...and they only cary HTR series of Yamaha.
Rob